effects of metals on chromosomes of higher organisms

Environmental Mutagenesis 9: 191-226 (1987)

Effects of Metals on Chromosomes of Higher Organisms Archana Sharma and Geeta Talukder

Centre for Advanced Study in Cell and Chromosome Research, Department of Botany, University of Calcutta, Calcutta 700 019, India

An analysis of the available data on the clastogenic effects of metals and their compounds on higher organisms indicates some general trends.

Following chronic exposure to subtoxic doses, a decrease in mitotic frequency and an increase in the number of chromosomal abnormalities are observed. These effects are usually directly proportional to the dose applied and the duration of treatment within the threshold limits. Recovery after acute treatment is inversely related to the dosage.

The ultimate expression of the effects depends on certain factors, including the mode and vehicle of administration; the form administered; the test system used; the rate of detoxification, distribution, and retention in the different tissues; and interaction with foreign and endogenous substances as well as the mode of action with the biological macromolecules.

In mammals, the clastogenic activity of the metals within each vertical group of the periodic table is directly proportional to the increase in atomic weight, electropositivity, and solubility of the metallic cations in water and lipids, except for Li and Ba. This pattern of inherent cytotoxicity increases with successive periods in the horizontal level. It is enhanced by the formation of covalent and coordinate covalent complexes by heavy metals with the biological macromolecules.

In plants, the solubility of the metals in water is of much greater importance. The degree of dissociation of metallic salts and the rate of absorption affect significantly the frequency of chromosomal aberrations.

In assessing the effects of environmental metal pollution, the presence of other metals and toxic chemicals and the level of nutrition should be taken into account, since in nature, metals occur in combination and these factors modify the cytotoxic effects to a significant extent.

Key words: clastogens, cytotoxicity, metal toxicity, metal pollution

INTRODUCTION

Following the rapid industrialization of the past decades, the increasing aware- ness of environmental pollution has led to a corresponding revival of interest in metals

Received March 25, 1986; revised and accepted September 9, 1986.

Address reprint requests to A. Sharma, Centre for Advanced Study in Cell and Chromosome Research, Department of Botany, University of Calcutta, 35 Ballygunge Circular Rd, Calcutta 700 019, India.

0 1987 Alan R. Liss, Inc.

192 Sharma and Talukder

as potential mutagens, carcinogens, and teratogens (Table I) [see Sharma, 1984a; Sharma and Sharma, 19811. Metals and their compounds form a large proportion of chemical pollutants, particularly in heavily industrialised regions. The harmful effects of metals on living organisms may be observed at histological, cellular, subcellular, or molecular levels and are modified by a number of variable factors, including the state of health of the organism concerned [see Sharma, 1984b; Venugopal and Luckey, 19781.

The mode of action of metals at the cellular level is diverse. They may affect the membrane system, changing the permeability of the cell or mitochondria1 membrane, which could disturb cellular energy metabolism; or they may decrease the stability of lysosomal membranes, which disrupt the cellular function through the release of acid hydrolases.

At the molecular level, metals may interact with proteins which could lead to denaturation, precipitation, allosteric effects, or effects on enzyme and protein synthesis. Alternatively, the metals may bind to the nucleic acids and alter the nucleopro- tein conformation. Either or both of these activities may affect cell division and the structure and behavior of the genetic apparatus.

Cytotoxic effects of metals have received and are receiving considerable atten- tion because of the identification of certain metals as carcinogens and teratogens. Metals causing genotoxic effects are often carcinogenic [Flessel et al, 19801. There is frequently, but not always, a positive correlation between the degree of mutagenicity of a metallic compound and the incidence of malignancy [Leonard, 19811, similar to

TABLE I. Effects of Different Groups of Metals

Metals shown to have mitostatic

and/or clastogenic Variable Not yet activity activity Nonclastogenic examined

Group I A Na, K Li Rb, Cs B c u Ag, Au

A Ca, Sr Mg Ba, Be, Ra B Zn, Cd, Hg

A Al, TI B, Ge, In B La, Ce Other lanthanides

Group I1

Group 111

and actinides Group IV

Group V A Su, Pb Ge

A As Sb, Bi B V Nb, Ta

A Se Te B Cr, Mo W

B Mn Tc, Re

Group VI

Group VII

Group VIII Fe, Co, Ni Ru, RG, Pd Os, Ir, F’t

Effects of Metals on Chromosomes of Higher Organisms 193

that recorded for other chemical toxicants [see ICPEMC report, 19831. However, this review has been largely restricted to effects on cell division and on chromosomes.

Effects on cell division and the induction of chromosomal abnormalities form important criteria for the identification of damage on genetic systems [see Hsu, 1982; Sharma and Sharma, 19801.

Alterations in cell division may lead to an increase in mitosis, a mitogenic action, or more frequently, to a reduction in divisional frequency, a mitostatic effect. Closely related are effects on the spindle apparatus, leading to the arrest of division or an imbalance in the separation of chromosomes. In plants, cell plate formation may also be inhibited. The high affinity of most metals for sulphur ligands destroys the spindle fibres. Therefore, spindle poisoning is a common phenomenon following metal treatment.

Changes in the chromosomes may involve alterations in number or structure or both. Agents causing breaks or exchanges of chromosome segments are termed clastogens, while numerical alterations are due principally to spindle dysfunction. Centromeric fission and/or fusion may also alter the chromosome number in certain cases. The end effects often overlap. The type and magnitude of the clastogenic effects usually depend on the stage of the cell cycle when the agent has been applied [see Sharma, 1984c for details].

METHODS AND TEST SYSTEMS (Table II)

Cytogenetic methods for identifying the action of chemicals on chromosomes can involve the measurement of either chromosomal alterations or sister chromatid exchanges (SCE). A combined analysis of the two end points provides the most reliable results.

Chromatid aberrations are more suitable than chromosomal alterations for obtaining quantitative data and should be analyzed at the first metaphase after treatment [see Hsu, 1982 for details]. With S-independent agents, action during GI and the early synthetic phase induces chromosome breaks, while effects on the synthetic and G2 phases results in chromatid-type aberrations. Exposure to S-dependent chemicals leads to chromatid-type breaks when single-strand breaks formed during GI or S phase are converted to double-strand ones during DNA replication [see Natarajan and Obe, 19801. The analysis of data from exposed human populations must take these factors into account.

An increase in SCEs is usually recorded at doses below those which cause chromosomal aberrations [Latt et al, 1982; Wolff, 19821. SCEs can be studied both in vivo and in vitro and, in combination with clastogenic assays, can be used to detect chromosomal damage induced by even very low concentrations of a chemical [see Ohno et al, 19821.

The micronucleus test, initially developed for bone marrow of animals in vivo, is able to detect clastogenic or nondisjunctional damage induced in the preceding division. It is suitable for routine screening owing to its relative simplicity and the rapidity of analysis [Heddle et al, 19831.

Chromosomes in germ cells of male animals can be observed in the dividing cells but the difficulty of the technique limits its utility for routine screening. In some cases, interphase chromatin can be monitored by premature chromosome condensation (PCC) [see Hittelman, 19821.

TABL

E 11

. Cla

stog

enic

Eff

ects

of M

etal

lic C

ompo

unds

on D

iffer

ent T

est S

yste

ms*

Met

allic

co

mpo

unds

PI

H

lc

Hpo

p M

amc

Mam

bm

Mam

gc

Trpl

SC

E

PI

Hlc

H

pop

Mam

c M

ambm

M

amgc

Ef

fect

s on

chr

omos

omes

Ef

fect

s on

spi

ndle

Gro

up IA

So

dium

A

rsen

ite

Azi

de

Chl

orid

e Fl

uorid

e N

itrat

e Se

leni

te

Sorb

ate

Pota

ssiu

m

Chl

orid

e Io

dide

So

rbat

e Li

thiu

m

Car

bona

te

Gro

up IE

i C

oppe

r Su

lpha

te

Mag

nesi

um

Sulp

hate

B

ariu

m

Chl

orid

e St

ront

ium

C

hlor

ide

Zinc

A

ceta

te

Chl

orid

e O

xide

C

adm

ium

Gro

up II

B

+ -

vv

+ +

+ +

+

V

++

-

+ ++

+

++

+

+-t

+

+S

+ + + + + +

+

+ +

(con

tinue

d)

TA

BL

E 1

1. C

last

ogen

ic E

ffec

ts o

f Met

allic

Com

poun

ds o

n D

iffer

ent T

est S

yste

ms*

(con

tinue

d)

Met

allic

co

mpo

unds

PI

H

lc

Hpo

p M

amc

Mam

bm

Mar

ngc

Trpl

SC

E PI

H

lc

Hpo

p M

amc

Mam

bm

Mam

gc

Effe

cts

on c

hrom

osom

es

Effe

cts

on s

pind

le

Ace

tate

C

hlor

ide

Sulp

hide

Org

anic

C

hlor

ide

Alu

min

ium

C

hlor

ide

Sulp

hate

Th

alliu

m

Lant

hanu

m

Chl

orid

e C

eriu

m

Nitr

ate

Gro

up N

A

Mer

cury

Gro

up II

IA

Tin St

anno

us

Stan

nic

chlo

ride

chlo

ride

Lead

A

ceta

te

Chl

orid

e C

hrom

ate

Nitr

ate

Sulp

hate

G

roup

VA

Ars

enic

N

a ar

sena

te

Na

arse

nite

+ +

+v

-

+to

++

-

+ V

-

+ +

+ ++

+

+to

++

+ + c

++

++

+t

- ++

++

++

++

+ +

+ +

+

+ +

+to

++

+

-

+

+ + + + c

+ k

++

+ +

+ ++

++

(con

tinue

d)

TA

BL

E 1

1. C

last

ogen

ic E

ffec

ts o

f M

etal

lic C

ompo

unds

on

Dif

fere

nt T

est S

yste

ms*

(co

ntin

ued)

t + + +

t

V

++

Met

allic

Ef

fect

s on

chr

omos

omes

Ef

fect

s on

spi

ndle

co

mpo

unds

PI

H

lc

Hpo

p M

amc

Mam

bm

Mam

gc

Trpl

SC

E

PI

Hlc

H

pop

Mam

c M

ambm

M

amgc

Gro

up V

B V

anad

ium

+

Gro

up V

IA

Sele

nium

+ -

Na

sele

nate

V

N

a se

leni

te

+ ++

+

Gro

up V

IE3

Chr

omiu

m

Ca

chro

mat

e Sr

chr

omat

e K

dich

rom

ate

Chr

omiu

m

triox

ide

Mol

ybde

num

Man

gane

se

Chl

orid

e K

Mn0

4

Gro

up V

W

Gro

up V

III

Iron

Cob

alt

Chl

orid

e +

Chl

orid

e +

Com

plex

sal

t N

icke

l Su

lphi

de

-v

+

V

Chl

orid

e +

+ Su

lpha

te

+ +

Com

dexe

s +

+ Pl

atin

um (1

1)

+ +

to+

+

+ +

+

+

*Abb

revi

atio

ns:

PI =

pla

nts;

Hlc

= h

uman

leu

cocy

te in

vitr

o; H

pop

= le

ucoc

ytes

fro

m e

xpos

ed h

uman

pop

ulat

ions

; M

ambm

= m

amm

alia

n bo

ne m

arro

w

in v

ivo;

Mam

c =

mam

mal

ian

cells

in c

ultu

re in

vitr

o; M

amgc

= m

amm

alia

n ge

rm c

ells

in v

ivo;

Trp

l =

tran

spla

cent

al e

ffec

t of

feta

l chr

omos

omes

; SC

E =

sis

ter c

hrom

atid

exc

hang

es.

+ =

mod

erat

e ef

fect

, + +

= s

ever

e ef

fect

, 5

= b

oth

posi

tive

and

nega

tive

effe

cts,

V =

var

iabl

e ef

fect

s, - =

no

effe

ct.


The hazards posed by metallic pollutants to organisms differ. Most of the metals induce some form of genotoxic damage. Of the numerous methods used to assess such toxicity, the most common ones employ microbial test systems, with or without microsomal enzyme inactivation, for point mutation studies. More elaborate techniques utilize higher organisms for measuring clastogenic effects and proliferative alterations both in vivo and in vitro, including transformation of cells in vitro [see De Serres and Hollaender, 1980; Hollaender and De Serres, 1971-1980; Kilbey et al, 1984; Sharma and Sharma, 1980; Sugimura et al, 1982, for details].

In higher organisms, particularly in mammalian systems, metals cause symp- toms of acute, chronic, latent, and recondite toxicity. These effects are directly related to the concentration used, the duration of treatment, the test system, and the mode of administration. The inherent toxicity of a metal depends on its capacity to disturb organ or cellular homeostasis by combining with cell organelles, macromolecules, and/or metabolites. Its toxicity is thus an expression of its electrochemical character (eg, solubility in body fluids, stability, and reactivity of its compounds within the organism), its ability to form stable chelates with biological macromolecules, and its physical form inside the target tissue. Thus, the rate of absorption and distribution of the metal within the organism are also related factors. Certain general conclusions have been arrived at regarding the relative toxicity of individual metals and of groups of metals of the atomic table [see Sigel, 1980-1984; Venugopal and Luckey, 19781.

In this review, the effects of metals as clastogens and spindle poisons in higher organisms have been summarized according to the position of the metal in the periodic table.

EFFECTS OF DIFFERENT GROUPS OF METALS, ARRANGED ACCORDING TO THE PERIODIC TABLE

The Group IA Alkali Metals Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs)

form stable, water-soluble salts. They exist as ions in biological fluids, rarely form bonds with macromolecules, are rapidly absorbed into blood and are distributed widely by moving across biological membranes. Several of these metals have de- monstrably clastogenic activity. This activity appears to relate, at least for Na and K, to the effect of high concentration on osmotic strength.

Sodium: The cytotoxic activity of sodium salts may be attributed to the anion linked with this metal. Sodium chloride, at concentrations which increased the osmolality of the medium above 600 mOsm/kg H20, induced a significant increase in both chromosomal aberrations and SCEs in Chinese hamster ovary cells after a 4-hr exposure period [Deasy et al, 19861. Sodium selenite induced SCEs in human leucocytes [Ray et al, 19781. Sodium sorbate was more strongly clastogenic and mutagenic than sorbic acid in Chinese hamster ovary cells in vitro [Hasegawa et al, 19841. At very low doses, sodium arsenite may stimulate DNA repair mechanisms, as shown by a reduction of chromosomal aberrations in Chinese hamster lung fibroblasts [Rossner and Sram, 19781. Chronic treatment of mice in vivo with sodium fluoride did not affect the chromosomes [Martin et al, 19791. Sodium fluoride, however, did cause a significant increase in chromatid-type aberrations in cultured human diploid fibroblasts [Tsutsui et al, 19841. This finding has been questioned by

198 Sharina and Talukder

later investigations [Thomson et al, 19851. Sodium nitrate exhibits clastogenic properties due possibly to the mutagenic activity of nitrate, which can be converted into nitroso compounds in the stomach. Oral administration of sodium nitrate to the mothers induced a dose-dependent increase in micronuclei in cultured Chinese hamster embryo fibroblasts [Inui et al, 19791. Chinese hamsters fed sodium nitrate showed endoreduplication and chromosomal aberrations in bone marrow cells [Tsuda and Kato, 19771. Prolonged feeding with subacute doses of sodium nitrate also induced micronuclei and chromosomal aberrations in the rat [Luca et al, 19851.

Potassium: Potassium chloride is strongly clastogenic and a weak inducer of SCEs in Chinese hamster ovary cells exposed in vitro for 4 hr to concentrations of KC1 which increase the osmolality of the medium above 600 mOsm/kg H20 [Deasy et al, 19861. Potassium sorbate was clastogenic but not mutagenic in Chinese hamster cells [Hasegawa et al, 19841. Potassium iodide was clastogenic in utero in pregnant female rates [Monakhova et al, 19761.

Rubidium, cesium. Cytotoxicity of Rb and Cs has not yet been studied, possibly owing to the rarity of their occurrence.

Lithium: The data on chromosome damage induced by lithium are conflicting. In certain patients undergoing lithium therapy, increased chromosomal abnormalities, including an increased incidence of satellite associations and a depressed mitotic index, have been recorded [Friedrich and Nielsen, 1969; Torre and Krompotic, 19751. However, a number of reports indicate the absence of an increased occurrence of chromosome breaks or SCEs induced in human subjects under continuous lithium treatment [Banduhn et al, 1980; Bille et al, 1975; Garson et al, 19811. The mitotic index is reduced in some patients [Genest and Villeneuve, 19711. Chromosomal aberrations were observed in a baby born to a mother treated with lithium but not in the mother [Aoki and Ruedy, 19711. In most cases the metal was used as carbonate. With the very low dosages administered, clastogenic effects may not be frequent enough to be observed. These contradictory reports may be due to the small sample sizes and the absence of suitable age- and sex-matched controls. However, the addition of lithium carbonate in vitro to human cultures also results in conflicting data [Timson and Prince, 19711.

In animal and plant test systems, spindle but not clastogenic effects were primarily observed in chronic treatment studies [Srivastava, 19851.

Group I6

Copper (Cu), silver (Ag), and gold (Au) show metabolic behavior quite different from the metals of group IA. Specific information about the clastogenicity of silver and gold are unavailable.

Copper: Only copper has a specific function in living tissues. It binds with the phosphate on nucleotides and nucleic acids, complexing in vitro in the cupric form with isolated and purified DNA from eukaryotic cells. It is a potential mutagenic agent owing to its property of inducing infidelity in DNA synthesis in vitro [Sideris et al, 19811.

In the sulphate form copper induces disintegration of chromatin and decreases the mitotic index, leading to lethality in plant systems following prolonged treatment with high doses [Singh and Sharma, 19811 (K. Aganval, personal communication). Earlier workers had attributed such cytological abnormalities to its interaction with


adenine [Frieden and Ales, 19581, but there is no experimental evidence to support this assumption.

No differences were found in the relative toxicities of CuC12, Cu(NO&, CuS04, Cu(OAc)*, and (NH4)2 CuC12 in mice [Hino et al, 19841. On the other hand, all molluscs (Lirnnueu stugnulis) died within 2 to 5 days with 5 or 10 mg/liter solutions of CuS04 [Shakmaev, 19841. Such differential toxicity appears to be related to the efficacy of absorptive and excretory mechanisms of different organisms but is not related to clastogenicity . The protective action of copper sulphate against lethality induced in mice by cis-diamine dichloroplatinum [Naganuma et al, 19841 has not yet been studied at the chromosomal level.

Group IIA Group IIA consists of beryllium (Be), magnesium (Mg), calcium (Ca), stron-

tium (St), barium (Ba), and radium (Ra) of which both Mg and Ca are essential macroelements for life forms. They are present as stable, water-soluble, cationic salts remaining in the ionic state in tissues.

Beryllium: Beryllium sulphate, a carcinogen, was found to be genotoxic in the Bacillus subti2is repair assay. However, the chloride and sulphate tetrahydrate forms, though known to be carcinogenic, gave a negative response to this test [ICPEMC group 5 , 19841. The metal shows high latent toxicity, which has not yet been studied at the chromosomal level.

Magnesium: Mg forms a variety of complexes in biological tissues. As a sulphate, it induced spindle disturbances in Allium cepu root cells following prolonged treatment and despiralization and differential chromosomal staining at higher doses [Singh, 19791. On the other hand, a Mg-deficient diet given to pregnant rats resulted in terminal deletions and fragments in both maternal and fetal liver cells [Hurley, 19781. Apparently the disturbances induced by the excess of Mg recorded in Alliurn test may be nonspecific, the result of an ionic disbalance rather than any specific action of the metal.

Calcium: This element is present in all higher organisms, forming coordination covalent bonding with mucopolysaccharides, mucoproteins, and plasma proteins. It chelates strongly with chelating agents and has a high affinity for phosphoryl groups. It is nontoxic. Cell division in plants has been suggested to be affected by an increase in the intracellular level of Ca2+, possibly through the formation of a Ca2+-calmodulin complex [Lambert, 1983; Malik et al, 1985; Rasmussen and Barrett, 1984; Roux and Slocum, 19821.

Calcium cyclamate was negative in micronucleus assays [Bruce and Heddle, 19791. Calcium lactate, a denaturant of the milk protein, casein, induced chromosomal aberrations, including breaks, in the grasshopper, Spathostemurn prusinifer. The magnitude of the decreased effect decreased with increasing duration of treatment. This complex may act on nucleoproteins, the chromosome breaks being me- diated through the haemolymph [Saha and Sircar, 19831.

Ion microscopy has shown that plant chromosomes serve as reservoirs of calcium during mitosis by concentrating this element at prophase. Calcium is trans- ferred to the nucleoli during telophase [Chandra et al, 19841. Exposure to a combination of Ca2+ (3 mM) and mercury (Hg2+) (1 mM), before fixation, condense the chromosome structure. In the presence of Ca2+ alone, the chromosome threads decondensed proportionately with decreasing Ca2 -+ concentration. Concentrations of


Ca2+ below 0.1 mM caused decondensation of deoxynucleoprotein fibrils in Chinese hamster cells [Zatsepina et al, 19831. These results are related to the role of calcium as an essential cell component.

Barium, radium: Barium has a very high affinity for sulphate and phosphate but a rather low affinity for -NH2, -SH, and -COOH groups. Clastogenic activity of this metal has not yet been investigated. High doses of BaC12 induce spindle disturbances in both submerged and terrestrial plant systems (T Das, personal communication). There is no record of the involvement of Ra in any biochemical systems or normal physiologic functions.

Strontium: This metal, like many metal ions, reacts with phosphate and carboxylate groups of biologically active molecules and binds to plasma proteins. It induced in a dose-dependent manner differential staining and uncoiling of plant chromosomes as well as spindle disturbances [Singh, 19791.

Group llB

The three post-transition metals of group IIB-zinc (Zn), cadmium (Cd),and mercury (Hg)-have been examined extensively for their cytotoxic effects. These metals exist in water-soluble, cationic forms and form coordination and chelation compounds in biological fluids with thiol ligands and albumins. Like many other metals, they bind to nucleotides and also inhibit enzyme activity. Their toxicity increases with electropositivity .

Zinc: Zinc in lymphocyte cultures (0.03 mg/ml) induced both chromatid gaps and breaks and decreased the mitotic index in a dose-dependent manner [Saksoong and Campiranon, 19831. Zinc acetate (7.0-21.0 pg/ml) induced chromosomal aberrations and diploidy in human lymphocytes exposed during Go phase. Zinc chloride was toxic to stimulated human lymphocyte cultures at 3 X lop3 M. Subtoxic doses, added to 48- and 72-hr cultures at zero and 24 hr after initiation, induced chromosomal aberrations, particularly fragments. Dicentric chromosomes were recorded only at the lowest concentration (3 X M) of ZnC12 added at time zero, regardless of the culture duration [Deknudt and Deminatti, 19781.

Chronic inhalation of ZnO aerosol (0.1 and 0.5 mg/m3) increased polyploidy in the bone marrow cells of rats [Voroshilin et al, 19781. However, intraperitoneal injection of ZnCl2 (15 mg/kg) did not induce chromosomal abberations in bone marrow cells of mice. Whether this difference was due to difference in the route of administration or in the chemical nature of the compound is not clear at present.

In Allium sutivum, ZnC12 induced chromosomal aberrations and reduced the mitotic frequency, the magnitude of which was directly proportional to dosage and duration of treatment. The aberrations mainly involved spindle disturbances, indicating the close affinity of the metal for thiol groups. The plants recovered from the effects of subtoxic doses [Mitra, 19841. The effects of Zn on plants are modified by its complex interaction with other essential nutrients present, such as Cu, Fe, Mg and Ca.

Cadmium: Cadmium, an extremely toxic element, is of special importance owing to its presence together with lead and zinc in refineries and smelters. A number of reviews are available on different aspects of cadmium toxicity [Degraeve, 1981; Mukherjee et al, 1984; Nriagu, 1980; Webb, 19791.

Earlier data on the clastogenic activity of cadmium salts in plants were contradictory. In Allium cepa, Cd salts were reported to induce spindle disturbances but not


chromosomal aberrations [Clain and Deysson, 19761. However, cadmium chloride was observed to induce both chromosomal aberrations and spindle disturbances in Allium cepu, Beta vulguris [Von Rosen, 1954a,b], Hordeum vulgure and Nigellu dumascena [Degreave, 1969, 1971; Moutschen-Dahmen et al, 19651, and Crepis cupilluris [Ruposhev, 1976; Ruposhev and Garina, 1976, 19771. The number of breaks was directly proportional to the concentration of CaC12 used; and in C. cupilluris, chromosome-type aberrations were more prevalent than chromatid ones. In Viciu fubu, fragments were located preferentially on the chromosomes bearing satellites [Glaess, 1955, 19561.

Later studies have shown more consistent results. In aquatic Eichhorniu crus- sipes, both mitostatic and spindle disturbance effects were proportional to dose and exposure duration [Rosas et al, 19841. At concentrations ranging from 1 x lo4 to 1 ppm, CdCl;? induced chromosomal alterations as well as spindle disturbances in a dose- and duration-dependent manner in Allium sutivum. Lesions were located at the secondary constriction regions, indicating their specific susceptibility. The mitotic index was not affected. Prolonged treatments with very high doses were ultimately lethal. The plants recovered progressively on being kept in nutrient medium [Mu- kherjee et al, 19841.

Analysis of DNA variations in Euglenu grucilis has located the site of the inhibitory action of cadmium ions to the Gz phase or later [Bariaud et al, 19801. Between pH 6.0 and 8.0, the pH and the anion used have no influence [see Degraeve, 1981 for review].

Cadmium binds to low molecular weight proteins in Cd-treated cabbage and tobacco plants to an extent directly proportional to the concentration of the metal and the total time of exposure, giving a complex very similar to the Cd-metallothionein formed in animals Wagner and Trotter, 19821. This property of cadmium to bind with protein and its high affinity for sulphur ligands are probably responsible for its action in disturbing the spindle. This mechanism of action is supported by the ability of 1-cysteine to inhibit the reactivity of cadmium [Vanlina et al, 19781.

Chromosomal aberrations and tetraploidy were recorded in the grasshopper, Poecilocerus pictus, following administration of cadmium salts [Kumaraswamy and Rajasekarasetty, 19771.

Mammalian cells in vitro give somewhat conflicting results dependent on the anion involved. CdS induced both chromatid and isochromatid breaks and translocations in cultured human leucocytes [Rohr and Bauchinger, 1976; Shiraishi et al, 19721. In other mammalian cell lines, such effects were induced only at toxic doses. Nontoxic doses were ineffective [see Deaven and Campbell, 1980; Mukherjee et al, 1984 for review]. Even following prolonged treatments, CdC12, despite its cytotoxic action, was not clastogenic in vitro mammalian systems. On the other hand, a low level of clastogenic damage, including gaps , chromatid-type deletions, and acentric fragments, was recorded after treatment of unstimulated human lymphocytes with cadmium acetate [Gasiorek and Bauchinger, 19811. The clastogenic activity of inorganic cadmium salts on mammalian systems in vitro is thus related both to the anion involved and to the specific test system used.

In in vivo mammalian systems, earlier experiments with CdC12 gave mostly negative results [Bruce and Heddle, 1979; Deknudt and Gerber, 1979; Epstein et al, 1972; Leonard et al, 1975; Ramaya and Pomerantzeva, 1977; Sutou et al, 19801. Later observations, however, were different. In female mice, CdC12 injected subcu-


taneously induced numerical but not structural aberrations in metaphase I1 oocytes [Shimada et al, 1976; Vilkina et al, 1978; Watanabe et al, 19791. Acute exposure to CdC12 for 6 hr led to breaks, deletion, and despiralization in rodent bone marrow chromosomes in a dose-dependent and exposure-dependent manner [Muramatsu et al, 19801.

With increasing sample time, acute oral administration of CdClz to mice reduced the mitotic index. At high concentrations of CdC12 (ie, 17.6 mg/100 g), the frequency of chromosomal abnormalities was enhanced significantly but later decreased with the recovery of the animal. A major proportion of the abnormalities involved spindle disturbances, including hyper- or hypoploidy [Mukherjee et al, 19841.

Following chronic exposure, 4 0 4 0 % of the retained Cd is accumulated in the liver and kidney, bound mainly to metallothionein of low molecular weight (l0,OOO to 12 ,OOO daltons). In general, the absorption of Cd when administered orally depends on the amount of the metal given rather than the form in which it is administered. In acute treatments there is an inverse relationship between the proportion of metal retained and the amount administered in single dose [see Bremner, 1974 for review]. The cytotoxic effect of Cd agrees with the retention of the metal. Following an acute dose there is an initial cytotoxic effect as shown by a high frequency of abnormalities and a decrease in mitotic frequency. Both effects are gradually reversed during recovery and may be attributed to the gradual loss of Cd from the system [Mukherjee et al, 1984, 19851.

In individuals exposed occupationally to cadmium, the data are conflicting, principally owing to presence of other heavy metals as well. A comparison of nonexposed and groups exposed to Cd alone did not show any significant or consistent changes in chromosomal aberration frequency [O’Riordan et al, 19781. Even in cattle fed on heavily contaminated hay, the frequency of aberrations was not significantly increased [Leonard et al, 19751.

Long exposure to CdC12 at subtoxic doses therefore apparently confers a tolerance, in spite of the relatively higher retention of the metal in the tissues. This tolerance may be attributed to the progressive increase in complexing with metallothionein, the production of which is accelerated by progressive Cd intake.

Mercury: This metal is a protoplasmic poison, cumulative and lethal to all species in higher concentrations [see Nriagu, 19791. The distribution and movement of mercurials in the environment have been studied in detail [see Mitra, 19851.

Though mainly a spindle poison, mercury compounds at higher doses also produce chromosomal abnormalities [Sayato and Nakamuro, 1980; Shiraishi and Yoshida, 1972; Shiraishi et al, 1972; Skerfving et al, 19701. Both phenyl- and methylmercury derivatives can inhibit spindle formation during mitosis [Fiskesjo, 1969, 1970; Ramel, 1969; Umeda et al, 19691.

Surveys of exposed human populations have indicated an increase of cells with structural chromosomal aberrations. However, except for exposure to ethyl mercury, the increase was not statistically significant. Elevation of Hg concentrations in blood resulted *in chromatid- and unstable chromosome-type aberrations and aneuploidy in cultured lymphocytes from 23 persons exposed to methylmercury [Skerfving et al, 19701. Lymphocyte cultures of subjects occupationally exposed to Hg compounds exhibited an increased rate of aneuploidy. Blood Hg levels could to some extent be correlated with the enhanced frequency of chromosomal aberrations [Verschaeve et al, 19761.


The frequency of chromosomal aberrations was significantly elevated in 22 men exposed to 0.15-0.44 mg Hg/m3. There was no statistically significant difference in the incidence of chromosomal aberrations between four individuals subjected to Hg vapor and 18 persons exposed to a mixture of HgC12 and ethyl and methylmercuric chlorides. Although not statistically significant, the frequencies of both chromatid gaps and breaks were increased in the exposed individuals. No chromatid interchanges were observed, and the frequency of aneuploid or polyploid cells was not altered [Popescu et al, 19791.

In leucocyte cultures of test human populations exposed to phenylmercuric acetate, the dissociation of acrocentric chromosomes was statistically significant [Kirsch-Volders et al, 19781 and there was an increase in centromere-centromere distances. Apparently the chemical influenced the D-group chromosomes involved in nucleolar organization. This effect was earlier attributed to a greater distance between SH-bearing molecules in that region or to a possible inhibition of specific enzymes regulating the nucleolar activity [Vershaeve et al, 1978, 1979bl. In human lymphocyte cultures treated during the GI phase with HgC12, a G-band-like pattern was observed in some metaphases (5-20%), a response which could not be confirmed [Vershaeve and Susanne, 19781. Chromosomal aberrations were not recorded [Umeda and Nish- imura, 19791. Exposure of human lymphocytes to both inorganic and organic mercurials during different phases of the cell cycle (G1-S to G1-M) indicate that chromosome segregation is altered at concentrations lower than that needed for clastogenicity . This effect on segregation may not be entirely due to the effect on spindle protein [Vershaeve et al, 1984, 19851 and interactions with other target molecules (eg, RNA polymerase I) may also be involved.

In animal studies, prolonged administration of Hg-contaminated tuna fish to cats increased the frequency of chromosomal aberrations in lymphocytes [Shiramizu et al, 19761. Repeated oral administration of phenylmercury acetate and Granosan (2 mg/ kg) to mice and of phenylmercury acetate (40 mg/kg) to swine enhanced the frequency of chromosomal aberrations and aneuploidy . Granosan was more harmful, to which mouse spermatocytes, but not the spennatogonia, were sensitive [Kalmykova and Poloz, 19781.

Chronic oral administration of HgCl2 to laboratory animals inhibited division in the bone marrow cells. These effects were enhanced 20 days after cessation of 6 days of treatment poshnakova and Vasileva, 19771. At higher doses, HgC12 exerted highly toxic effects. Chromosomal abnormalities-including both. spindle disturbances and chromatid breaks, gaps, and deletions-were induced, the magnitude of the response being directly proportional to the duration and dosage of treatment [Das et al, 19821. A single acute dose was more toxic than chronic exposure to the same amount [Das et al, 19831.

Cell proliferation of mouse glioma was completely suppressed by treatment with 5 x lop5 M HgC12. The mitotic index remained normal for 4 hr after treatment but decreased afterwards. The amount of mercury (Hg2+) ion bound to the cells increased markedly above 2 X M HgC12 [Miura et al., 19791. In fish, a significant increase in chromosomal aberrations was not seen even after 120 days of exposure to 0.1 ppm inorganic mercury [Gutierrez et al, 19841.

Administered as a single injection to Syrian hamster 24 hr before sacrifice, methylmercury severely damaged the chromosomes in bone marrow cells. The effect did not appear to be related to dosage [Mailhes, 19841. In the meiosis of mouse ova,


threshold levels of both inorganic and methylmercury induced severe aberrations, while inhibiting spermatogonial DNA synthesis in male mice [Lee and Dixon, 19751.

Chromosomal aberrations (up to 65%) were induced in a normal diploid strain of Chinese hamster cells after treatment with CH3HgC1 (0.1-10.0 ppm) for 2 hr. A high frequency of cells (up to 51 %) showed multiple breaks, including pulverization, single chromatid and isochromatid breaks, and also reunions and rearrangements (up to 17%) distributed nonrandomly [Kato, 1976; Watanabe et al, 19821. HeLa cells, when incubated with methylmercury, showed disturbances in cell viability only after 105 hr [Gruenwedel and Friend, 19801. Mercury, over the concentration range of 1-5pg, gradually decreased the frequency of mitosis and increased the frequency of chromosomal aberrations in ludney tubular cell cultures [Stadnicka, 19781.

The data available indicate that inorganic salts of mercury induce chromosomal abnormalities when given at higher doses or for prolonged periods in vivo. The effects are more severe with organic mercurial compound and may be related to the availability of binding sites at lower doses. Mercury compounds interact with the spindle apparatus, probably because of their affinity for thiol groups.

Sodium selenite gave a marked protection against chromosome breakage induced by Hg compounds [Das et al, 19851. On the other hand, chromosome breakage by sodium selenite was inhibited by MeHgCl and HgC12, the latter being more effective than the former to human lymphocytes [Sayato and Nakamuro, 19801.

Group MA Group IIIA includes the elements boron (B), aluminium (Al), gallium (Ga),

indium (In), and thallium (Th). These elements form coordination complexes and compound salts. However, their salts undergo hydrolysis in aqueous solutions as well as in biological fluids, preventing their complete absorption through biological membranes.

Aluminium: A mitodepressive action of 0.001-0.1 M AlC13 and A1*(S04), was observed after 24 hr on roots of Vicia faba; the effect was irreversible at higher concentrations. The types of chromosomal aberrations induced by the treatment included fragments and bridges in anaphase or telophase, micronuclei, and binuclear cells. The metal accumulated in the roots, particularly in the nucleus and cytoplasm near the wall [Wojciechowska and Kocik, 19831. Root elongation following inhibited cell division was also observed in Vigna unquiculatu. The more sensitive secondary roots showed a drastic reduction in cell division after 5 hr and complete inhibition after 10 hr. However, after 18 hr, cell division restarted even in the presence of aluminium, indicating a recovery from primary shock [Horst et al, 19831.

In roots of Cucurbita pepo, Vicia faba, Glycine m, Lycopersicum esculentum, Pisum sativum, Phaseolus angularis, Lactuca sativa, Zea mays, and Arctium lappa, the aluminium content was positively correlated with the cation exchange capacity of the dry root powder [Wagatsuma, 19831. Most of the aluminium is apparently bound to pectic substances in the cell walls, but a part enters the protoplast to combine with nucleic acids and acid-soluble phosphates. The destruction of roots and high concentrations of Al in the medium may increase the passive movement of A1 into the protoplast,

Chronic oral administration of aluminum sulphate and its complex with potassium and ferric sulphates induced spindle disturbances in vivo in mice (A.K. Roy, personal communication).


Thallium: The only report of chromosome breakage and spindle abnormalities by diffferent thallium salts is on AZZium cepa [Ravindran, 19711, which needs confirmation.

Group IllB

In group IIIB, the lathanides and actinides are included, in addition to scandium and yttrium. They are usually considered as nontoxic owing to their poor absorption.

Lanthanum (La): Intraperitoneal injection of lanthanum trichloride caused an appreciable increase in mitotic index and in the nuclear volume of liver cells and an immediate decrease in the mitotic index of rat and mouse bone marrow cells [T Das et al, 1983; De and Sharma, 19811. The effect is possibly tissue specific, directly related to treatment duration and mode of administration but is noncumulative in nature.

Cerium (Ce): In the form of ceric sulphate, Ce caused differential destaining of chromosome segments in plants [Singh, 19791. Though not to a marked extent, cerium as a nitrate induced breaks and reduced the mitotic index in rat bone marrow in vivo. This element is known to affect the nucleotides and to accumulate in the bone through its affinity with phosphates, leading to its cytotoxic activity [Giri et al, 19791.

Group IVA Of the metals under Group IVA, namely, germanium (Ge), tin (Sn), and Lead

(Pb), the last one is the metal best known for its cytotoxic effects. However, cytotoxicity has not been studied in the metals of group IVB-namely, titanium (Ti), zirconium (Zi), and hafnium (Hf).

The salts of Sn and Pb are more toxic than those of the other metals. The organometallic compounds of Ge, Sn, and Pb are more toxic than the inorganic salts, owing to their greater lipid solubility, stability in biological fluids, and penetration into biological tissues.

Tin: Tin, as stannous chloride (SnC12), produced extensive DNA damage in Chinese hamster ovary cells, about 200 times more than the known carcinogen, chromium. This damage was repaired totally after 6 days. On the other hand, stannic chloride (SnCb) did not induce any chromosomal damage [McLean et al, 1983al. A similar effect was observed on the DNA in human white blood cells [McLean et al, 1983bl. Addition of SnClz to human leucocyte cultures induced mainly alterations in divisional frequency (B.B. Ghosh, personal communication). Since tin is a vital element [Carderelli, 19851 , further information is required.

Lead: This metal has a long antecedent history of toxicity associated with its widespread use in human cultivation [see Nriagu, 19781. The metal forms insoluble phosphates and interacts covalently with tertiary phosphate ions in the nucleic acid [Claysson, 1962; Hueper and Conway, 19641. These are electrophiles in their ionic forms and require metabolic activation into reactive electrophilic groups which combine covalently with nucleophilic sites in DNA, RNA and protein and result in cytotoxic effects [Bremner, 1974; Lessler and Walters, 1973; Miller and Miller, 19761.

Lead salts have been shown to be cytotoxic in plant systems [Von Rosen, 19541. They are mitostatic and lead to reduced growth [Mukherji and Maitra, 19761. In Crepis cupilZuris, the clastogenic action of lead nitrate was independent of the stage of the cell cycle [Ruposhev, 19761. Although lead chloride inhibited cell growth and


delayed cell division in certain algae, the mutation frequency was not enhanced [Hessler, 19751. The concentration required to inhibit cell division varied widely between different groups of algae, being partially influenced by their photosynthetic activity and phosphate metabolism [Rai et al, 19811. Electron microscopy of the unicellular alga, Poterioochromonas malhumensis, showed that lead caused deformation of nuclei, structural alterations of mitochondria, and an increase of autolytic activity in all cell organelles [Roederer, 19841.

Allium cepa, exposed to lead acetate for short periods, exhibited disturbance of the spindle, while, following longer treatments, damage of the cellular and chromatin matter occurred [Dhir, 1984; Singh and Sharma, 19811. Recovery was possible only with very low dosages (10 ppm) [Singh and Sharma, 19821. Trimethyl-, triethyl- and diethyl-lead chlorides at concentrations between lop6 and mM caused disturbances in the spindle apparatus of Allium cepa.

The clastogenic and spindle-disturbance activity of lead, as nitrate, on plant cells, differs in submerged and terrestrial systems. In the former, the duration of treatment was the principal factor, while in terrestrial forms, dosage played a more important role [Dhir, 19841. These differences may be related to the mode of entry, being through the root system alone in terrestrial forms and both through foliar and root absorption in submerged form. Longer durations and higher concentrations however, were lethal in both types of plants.

Compounds of lead, both inorganic and organic, have been tested for their action of spindle formation and chromosomal &vision in animal systems ranging from Chironomous larvae [Rathore and Swamp, 19821 to exposed workers in lead smelters [Nordensen et al, 1978bl. The observations conflict, which may be partially attributed to the route of administration and to the test system used.

Chromosomal aberrations or SCEs were not induced in Chinese hamster cell cultures by different lead salts [Bauchinger and Schmid, 1972; Douglas et al, 19801. No chromosomal effects were detected in bone marrow cells of rats [Fomenko et al, 19821, cattle [Leonard et al, 19741, and mice [Deknudt and Gerber, 1979; Leonard et al, 19721; in HeLa cells in vitro or in peripheral lymphocytes from exposed workers [Bauchinger et al, 1972, 1976; Bui et al, 1975; Gasiorek and Bauchinger, 1981; O’Riordan and Evans, 1974; Stella et al, 19791 and from children exposed to lead [Bauchinger et al, 19771.

On the other hand, a significant correlation was observed between lead toxicity in vivo and chromosomal aberrations, from minor ones to major gross ones like dicentrics, rings, and translocations [Bauchinger and Schmid, 1972; Beek and Obe, 1974; Deknudt et al, 1977; Flessel, 1978; Gerber et al, 1980; Jacquet et al, 1977; Jacquet and Techon, 1981; Verschaeve et al, 19791. The effects again depended to a large extent on the test system, the concentration of lead and the duration of the exposure, and other factors like diet.

Fetal mice exhibited chromosomal aberrations in liver cells following prolonged treatments of the clam with lead nitrate during pregnancy [Nagymajiteryi et al, 19841. Chronic oral administration of lead nitrate to mice also decreased the mitotic frequency in bone marrow, an effect which was related to the concentration of the chemical but not to the duration of the exposure. The frequency of chromosomal abnormalities induced, however, increased both with concentration and with treatment duration. Spindle disturbances were most frequent. Since lead has an affinity for sulphydryl groups, particularly di-thiols, it has been suggested that in its presence, a


series of reactions takes place on the membrane. First, an S-S bridge breaks open to give an S-Pb complex, after which an S-Pb-5 complex is slowly formed. Clastogenic damage also increased progressively with the concentrations used, with dicentrics being observed only at high doses. Very high concentrations of lead nitrate were lethal [Dhir, 19841. A single acute oral dose of lead nitrate resulted in an initial decrease in mitotic frequency and an increase of the frequency of abnormal cells. The mice recovered on being kept on a normal diet, the period of recovery being directly proportional to the concentration of lead administered [Dhir, 19841. Since the animals were kept on a normal diet, the observations of Deknudt et a1 [1977] that clastogenic effects resulting from exposure to lead are related to calcium deficiency do not appear to be valid.

In rats, when injected intraperitoneally at different doses using acute or chronic exposure protocols, lead acetate consistently induced high frequencies of chromosomal alterations [Chatterjee, 19851. Prolonged oral treatment for 6 months with high doses of lead significantly increased the frequency of chromosomal aberrations in the bone marrow. It has been suggested that lead acts preferentially on the chromosomes rather than on the spindle apparatus [Verschaeve et al, 1979al.

Sister chromatid exchanges were reported after treatment of human lymphocytes with lead sulphate [wolff, 19821 and triethyl lead chloride [Grandjean and Anderson, 19821. Chronic lead exposure affected both gonads and spermatogenesis in male rats and mice [Fomenko et al, 1982; Wyrobek and Bruce, 19781. DNA damage did not occur in Chinese hamster ovary cells treated in vitro, although dose-related increases in chromosomal aberrations were observed with lead chromate [Douglas et al, 19801.

Whether or not occupational exposure to lead results in the induction of chromosomal alterations and/or SCEs still remains unresolved, with both positive and negative data being available [Beckman et al, 1982; Beck and Obe, 1974; Gerber et al, 1980; Nordenson et al, 1978a, 1982; O’Riordan and Evans, 1974; Quazi et al, 19801. Leucocyte cultures from workers exposed to several metals in combination have, however, given consistently higher frequencies of chromosomal anomalies than the controls. Such cultures were obtained from tank cleaners exposed to Pb, Hg, arsenic, and Cd [Hoegstedt et al, 1981; Schwanitz et al, 19751 and Pb, Cd, and Zn [Grandjean et al, 1983; Maki-Paakkanen et al, 19811.

The mechanism of action of lead on cell division is not fully understood. Under certain conditions, lead is stimulatory, causing enhanced protein synthesis and increased erythropoiesis , respiration, DNA synthesis, cell replication and reproduction [Luckey, 19751. Usually, a single dose results in enlargement of the liver, accom- panied by an increase in total protein and DNA content [Ledda et al, 19821. Mitosis is induced in both parenchymal and nonparenchymal cells of the liver [Columbano et al, 19831. However, the increased proliferative capacity was reduced progressively following repeated administration of the metal [Ledda-Columbano et al, 19831. It has been suggested that a single injection leads to the arrest of a large number of mitotic cells in the G2 phase after a burst of DNA synthesis. Since total amounts of DNA and proteins increased in renal cells before the onset of DNA synthesis, lead was regarded to induce DNA replication by stimulating new RNA transcription and new protein synthesis [Choie and Richter, 1973, 1978; Ruben and Sunderlingam, 19831.

A similar increase in mitotic activity, without a corresponding increase in chromosomal aberrations, has been observed in male volunteers following lead ingestion pjilsma and de France, 19761. The exposure was associated with several


other phenomena, which might affect mitotic activity, such as stimulation of the cyclic AMP system [Stevenson et al, 19771. On the other hand, a significantly increased induction of chromatid- and chromosome-type aberrations has been recorded in both male and female subjects occupationally exposed to lead [Forni et al, 19801. The period of culture was an important factor since the positive results were usually obtained after culturing the leucocytes for 3 days. Lead acetate also increased the content of sulphydryl groups in kidneys of treated mice [Ono et al, 19783, with a substantial increase of peptide synthesis in the kidneys [Kulizewski and Nicholls, 19831.

Unlike in the liver, a mitostatic effect of lead on the bone marrow system was uniformly observed [Chatterjee, 1985; Columbano et al, 1983; Dhir, 1984; Ledda et al, 1982; Ledda-Columbano et al, 19831. Chronic intoxication with small doses of lead is known to affect peripheral blood indices which correlate with disruption processes in the bone marrow [Sudakova et al, 19831.

Group VA In group VA, the metalloid arsenic (As) has been studied in detail, while

information on clastogenicity of antimony (Sb) and bismuth (Bi) is not yet available. Arsenic: Arsenicals appear to be powerful clastogens. These compounds have

been shown to reduce cell survival m a n et al, 19821, retard cell growth m e n et al, 19811 and SCEs [Zanzoni and Jung, 19801 in different mammalian cells [Larramendy et al, 19811. However, arsenicals do not appear to be mutagenic [Rossman et al, 19801.

No reliable evidence of direct carcinogenicity of arsenicals is available in experimental animals, though there is a strong correlation between arsenic exposure and the increased incidence of human skin and lung cancers [IARC, 1980; Leonard and Lauwerys, 1980a; Sunderman, 19791. However, carcinogenic activity is suggested by the induction of morphological cell transformation [DiPaolo and Casto, 19791, and the enhancement of transformation of Syrian hamster embryo cells with simian adenovirus [Casto et al, 19791. Also, this metal may act as a carcinogen or promoter as suggested by its ability to enhance the incidence of diethyl-nitrosamine- induced kidney tumors in rats [Shirachi et al, 19831 and by the increase in cytotoxicity and clastogenicity of ultraviolet (UV) light in Chinese hamster ovary (CHO) cells caused by sodium arsenite [Lee et al, 19853.

In vitro exposure of mouse fibroblasts to arsenicals induced chromosomal and spindle aberrations [King and Lunford, 19501. Leucocyte and dermal fibroblast cultures of human subjects, exposed to both potassium and sodium as arsenite and arsenate, exhibited chromosomal rearrangements and breaks [Nordensen et al, 1978a; Oppenheim and Fishbein, 1965; Paton and Allinson, 1972; Petres et al, 19701. Aberrations as well as elevated SCEs were observed in skin cancer patients exposed to long term arsenic therapy [Burgdorf et al, 1977; Leonard and Lauwerys, 19801.

Sodium arsenate, however, induced spindle disturbances but not chromosome breaks in AZZium cepa [Singh, 19791. Both spindle disturbance and chromosomal breaks in bone marrow cells were appreciably increased following chronic oral administration of sodium arsenate to rats in vivo for 3 wk [Giri et al, 19811. The mitostatic activity of sodium arsenate in both plants and animals was equal to that of sodium molybdate, with a significant decrease in total DNA and RNA contents observed in all organs [Giri et al, 19841. Arsenic has been suggested to act by


substituting for phosphorus in DNA, thus changing a weak bond in the DNA mole- cule. Also DNA-protein cross linkages may occur since both arsenate and arsenite decrease the extractability of DNA tumor cells [Grunicke et al, 19731.

Group VB Of the three elements in group VB, vanadium (V) has been studied quite widely

for its cytotoxic effects. It forms a large number of active water-soluble salts, the pentavalent forms being more toxic than trivalent ones. In AZlium cepu exposed to vanadium in the pentoxide form, higher doses induced pycnosis and loss of chromatin matter, while lower doses poisoned the spindle [Singh, 19791. Chronic oral administration of V to rats was not clastogenic, although the mitotic index was lowered [Giri etal, 19791. No concrete data is available on the carcinogenic, mutagenic, or teratogenic effects of vanadium exposure on humans or experimental animals [Roschin, 1967; Stokmger, 19671.

Group VIA

In group VIA,with selenium (Se), tellurium (Te), and polonium (Po), the former two are stable only in anionic forms. Selenium, although essential for animals, is the most toxic metal of this group and in low doses, is antagonistic to certain other metals [Das et al, 19851. Its toxicity varies according to the chemical form and the species involved.

Selenium: Sodium selenite treatment before meiosis reduced recombination and caused alterations in chromosome structure in barley [Walker and Ting, 19671. Both selenite and selenate induced mitotic disturbances [Sentein, 19671. Sodium selenite reduced mutagenicity of both direct mutagens and those requiring metabolic activation [Martin and Schillaci, 19841. It was seen to fragment DNA, trigger DNA- repair synthesis, and induce chromosomal aberrations in human fibroblasts [Lo et al, 19781 and Chinese hamster cells in vitro [Noda et al, 19791. It was mitostatic in vivo in rabbits and pigs [Fukina and Kudriyatseva, 19701. Genetic damage was induced through reaction of Se with DNA [Nakamuro et al, 19761. SCE frequency was increased in Don cells by K2Se03 [Haruki, 19831. Clastogenic damage was induced in Chinese hamster bone marrow at near lethal doses [Norppa et al, 1980al and in rat bone marrow cells [Newton and Lilly, 19861 by sodium selenite following interactions injections. Sodium selenite also induced both chromosome breaks and spindle disturbances in AZZium cepu [Singh, 19791, and, when administered orally, in rat bone marrow [Giri et al, 19811. The effects were initially high, followed by a leveling off by 3 wk for both chronic and acute exposures in mice and rats [Das, 1982; Mitra, 19841.

Selenium replaces the sulphur atom in -SH group [Cummis and Martin, 1961; Ganther, 19681, and functional and structural proteins undergo conformational changes if seleno-trisulphide cross-links are formed between -SH and selenites, possibly accounting for its spindle-disturbing effects [Singh and Sharma, 19811. A decrease in SCEs has been related to the increase in valence states as selenium (Se') > selenium dioxide (Se4+) > sodium selenide (Se2-) > sodium selenite (Se4+) > sodium selenate (Se6'), the last form being unable to produce SCE even at high concentrations [Ray and Altenburg, 19801. A metabolite of Na2Se03, other than plasma protein bound Se, is responsible for its SCE-inducing ability in human whole blood cultures [Ray and Altenburg, 19821.


The effects of selenite and selenate in different in vivo mammalian systems range from noncarcinogenic to teratogenic to anticarcinogenic [see Griffith, 19791. Chromosomal aberrations were reduced during its anticarcinogenic action on mice [Shamberger, 19741. Sodium selenite injected to neuronal ceroid lipofuchsinosis patients did not induce chromosomal aberrations in lymphocyte cultures [Norppa et al, 1980bl. Sodim selenite also did not induce aberrations in the lymphocytes of rats [Newton and Lilly, 19861 or in the bone marrow or germ cells of male NMRI mice [Norppa et al, 1980~1. When compared with sodium arsenate and molybdate, the clastogenic and mitotastic properties of sodium selenate may be graded as As > Mo > Se, supported by their action on total nuclei acid and protein contents [Giri et al, 19801.

Group VIB Group VIB includes chromium (Cr), molybdenum (Mo), and tungsten (W). Of

these, Cr exists in stable cationic and anionic forms, while cationic Mo and W salts are less stable. The anionic salts are readily absorbed in biological systems. The order of toxicity of group VI metals is Se> Te > Mo > Cr6+ > W > Cr3+. However, no clastogenic effect has been recorded with tungsten salts.

Chromium: Chromium salts induce cytotoxic, mutagenic, clastogenic and carcinogenic effects [Leonard and Lauwerys, 1980b; Venier et al., 19821. Following occupational exposure to chromium fumes for long periods, workers show an increased frequency of chromosomal breaks [Bigalieve et al, 19781 and SCEs in leucocyte cultures [Singh and Bhargava, 1983; Stella et al, 19821. In human lymphocytes cultures, the frequency of SCEs increased with increasing dosage of chromium salts [Gomez-Arroyo et al, 19811. Chromium was also found to induce base-pair substitutions in mammalian cells in culture [Rainaldi et al, 19821. K2Cr207, K2Cr04 and Cr03, at lop4 M concentrations, induced both chromosome breaks and exchanges in cultured mammalian cells, but the inactive trivalent Cr2(SO4>, failed to do so [Umeda and Nishimura, 19791. However, chromium tannis, containing mainly trivalent chromium sulphates, increased the SCE frequency significantly in Chinese hamster ovary cells but did not induce gene mutations [Venier et al, 19851. Calcium chromate and strontium chromate, although carcinogenic in rodents and mutagenic in bacterial assays, was not clastogenic [ICPEMC, 19841. The clastogenicity of K2Cr207 was tissue specific as well, since, when injected intraperitoneally, this compound was highly damaging to bone marrow cells of rats but much less so to lymphocytes [Newton and Lilly, 19861.

Molybdenum: This metal combines with serum proteins, flavoproteins, and enzymes, affecting tissue metabolism. Its metabolism in animals is similar to Cu and iron. Oral administration of sodium molybdate to rats daily for 3 weeks reduced the mitotic index and increased the frequency of chromosome breaks and gaps and spindle disturbance [Giri et al, 19811. The effects in plants were higher than those induced by rubidium and copper but lower than those induced by arsenate and selenate [Singh and Sharma, 19801. As molybdenum oxide and metabolic molybdenum, the metal is known to affect different mammalian organ systems, in vivo, but no other data are available on clastogenic effects.

Groups VIIA,B

None of the elements of group VIIA are metals. In group VIIB, manganese (Mn) is essential to mammals and is involved in metalloenzyme systems, while


technetium (Tc) and rhenium (Re) are not. Divalent Mn coordinates with ligands to give an octahedral complex in biological systems, while Mn3+ is the biologically active form in mammals. Mn2+ is known to substitute for Mg2+, increasing the incorporation of noncomplementary deoxyribonucleotides and complementary ribon- ucleotides in vitro in avian myeloblasts [Dube and Loeb, 19751.

In Allium, treatment with manganese chloride resulted in spindle disturbances, culminating in lethality with increased dosage [Singh, 19791. Manganese chloride

M) also induced breaks, fragments, and exchanges in cultured mammalian cells, while KMn04, was clastogenic at concentrations above M. The effects were enhanced at longer durations of treatment [Umeda and Nishimura, 19791.

Group VlllB In group VILIB, the nine elements, iron (Fe), cobalt (Co), and nickel (Ni),

ruthenium (Ru), rhodium (Rh), and palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt), form three triads of chemically similar metals. Iron and cobalt are considered essential to life forms and nickel stimulatory, but the other two triads are not essential. The atomic structures of these metals have a dominant role in determin- ing their biological activity. In biological fluids, these metals, except Pd and Os, form stable compounds.

Iron: This metal is essential for all organisms and is important physiologically both in di- and trivalent states. The latter in the ionic form has a greater affinity for oxygen-containing ligands . It accumulates in polymorphonuclear leucocyte lysosomes owing to its affinity for acidic glycoproteins and basic proteins. Some Fe compounds, like iron-dextran complexes, may act as cocarcinogens.

At lower concentrations, inorganic iron salts have been shown to weakly induce spindle disturbances in Allium cepa root tips [Levan, 1945; Singh and Sharma, 1980; Von Rosen, 19571. Longer durations and higher concentrations induced gradual toxicity and nonspecific effects. The action on spindle may be attributed to the tendency of metals in excess to chelate with ionic groups, disturbing the ionic balance of the cell [Kihlman, 1966, 19711.

A decrease in divisional frequency and an increase in chromosomal abnormalities were recorded with higher doses of ferric chloride in both submerged Vallisneria spiralis and terrestrial Allium sativum. The latter plants recovered even after being subjected to toxic doses. The more drastic action of ferric chloride on submerged plants may be attributed to greater absorption of the metal through both the root systems and foliage [Dhir et al, 1985~1.

Chronic treatment of mice with iron resulted in a progressive decrease in mitotic frequency with increasing concentrations, but not with exposure duration. The frequency of chromosomally abnormal cells increased slowly as a function of the concentration and the period of treatment. Spindle disturbances formed the greater majority of damage, possibly owing to the affinity of the metal for the sulphur ligands in the plasma proteins. With enhanced concentrations, chromatin matter was affected, followed by toxicity of the cellular components [Dhir et al, 1985al.

In mouse, as in man, an increase in the oral dose of iron results in an enhancement of the total amount of iron absorbed but a decrease in the relative fraction of the dose absorbed [Gitlin and Cruchand, 19621. In the rare genetic disease haemochromatosis, an excess amount of iron is absorbed and deposited in the vital organs, leading to their degeneration [Dreyfus and Schapira, 19641. The immediate


decrease in mitotic index and its constancy at that level may be explained by the observation that with higher concentrations, although a greater amount of iron is administered, that available for mitotic inhibition is not proportionally as high.

Cobalt: Divalent cobalt irons activate a number of enzymes in vivo. The binding capacity of the proteins with Co depends on amino acid availability [Wilberg et al, 19691, cobalt has also been reported to inactivate thiol groups [Heggtveit et al, 19701. This metal has been suggested to form permanent combinations with purine and pyrimidine bases as well as with DNA since treatment with this metal causes a distinct decrease in the content of nucleic acids, proteins and mucopolysaccharides [Liquier-Milward, 19511.

In AZZium cepa root tip cells, chromosome breaks were observed with CoC12 treatment [Singh, 19791. The cobalt (111) complexes-namely [Co(BSOP)(NH3)2] and CO(BSOP)(PY)~ (NO3)-induced diplochromatids, stickiness, erosion, fragmentation, bridges, and granulation of interphase nucleus related to dose and duration. An extreme effect was noted following a 5-hr treatment with 0.25-mg/ml solutions of both complexes. No aberration persisted after a recovery of 5-7 days [Tribedi et al, 19841. Single Co-salts reduced the rate of cell division, inhibited passage of interphase cells into prophase, and produced clumping and stickiness of chromosomes in Viciu faba [Herich, 19651.

Chronic oral administration of CoCl2 induced an increase in the number of dividing cells in rat bone marrow and in the occurrence of chromosome breaks and gaps, as well as stickiness. The response was much lower than that observed for Ni [Sanyal et al, 19801.

Nickel: Most simple salts of nickel are water-soluble. It has little affinity for sulphur ligands but reacts with amino acids. It occurs as a metalloprotein in serum and is present in RNA from different sources.

Reports on clastogenic properties of nickel are contradictory [Leonard et al, 19811. Nickel sulphide was claimed to cause mitotic aberrations and abnormal figures in cultured embryonic rat muscle cells [Swierenga and Basrur, 19681. Such effects were not seen in human leucocytes cultured in the presence of metallic nickel or nickel oxide powders [Paton and Allinson, 19721. In cells from a C3H mouse mammary carcinoma, only a few aberrations were seen after treatment with NiC12 or with Ni (CH&00)2. K2Ni(CN) only produced gaps, whereas Ni2S3 inceased significantly the yield of chromosomal aberrations (Umeda and Nishimura, 19791. How- ever, when the cells treated with Ni salts were allowed to recover in control medium, chromosomal aberrations were observed after treatment with all four salts [Nishimura and Umeda, 19791.

The mode of administration appears to influence the results. Chronic intraperitoneal injection of nickel sulphate (3-6 mg/kg) to rats for 7 to14 days did not induce any aberrations in bone marrow cells [Mathur et al, 19781, while chronic oral administration enhanced the mitotic index as well as the frequency of chromosomal breaks and spindle disturbances [Sanyal et al, 19801.

Amongst plants, Komczynski et al [ 19631, confirming previous results of Glaess [1955, 19561, demonstrated that Ni(N03)2, NiC12, and NiS04 produced in vivo nuclear alterations and deformation in the broad bean, Vicia faba. NiS04 treatment on AZZium cepa root tip cells resulted in condensation and contraction of chromosomes [Singh, 19791.


Both NiC12 and crystalline NiS induced DNA strand and chromosome breaks and exchanges in cultured Chinese hamster ovary cells, depending on the concentration and duration of treatment. The heterochromatic long arm of X chromosome showed a greater susceptibility to breaks by NiS, which has been attributed to the mechanism of Ni2+ delivery in cells [Robison and Costa, 1982; Sen and Costa, 19851.

Chromosome gaps but not SCEs were increased in a small group of workers exposed to Ni3S2, NiO, NiC12, and NiS04 [Wakswik et al, 19841. Since no details were given about the number of cells scored, the possible simultaneous exposure to other environmental mutagens or the criteria used for selecting the control group, these results are not conclusive.

In summary, nickel, particularly as sulphide, appears to be weakly clastogenic. The effects depend on the rate of uptake and the concentration used.

Platinum: Platinum (II) complexes induced delayed aberrations, mainly isochromatid and chromatid translocations, both in Chinese hamster bone marrow cells [Fremuth et al, 19721 and in the plant Crepis cupilhris. The cis isomers were more strongly clastogenic than the trans isomers. This property has been related to the structural active complex-a cis grouping with two N-donor ligands [Shevchenko et al, 19831.

GENERAL COMMENTS

First, the effects of metals on chromosomes and cell division in higher organisms show certain general trends. The mitotic index usually decreases with an increase in dosage and the period of treatment. Effects on cell division include spindle disturbances, leading to metaphase arrest, stathmokinesis, diplochromatid formation, chromosome lagging, and ultimately polyploidy . These responses may be attributed to the affinity of metals for sulphur ligands and consequently for spindle proteins [see Cherian, 19851 and, to a certain extent, to changes in osmotic concentrations in tissues. For example, cadmium binds with proteins of low molecular weight, and its retention in the tissue depends on the formation of such metallothioneins. Chromo- somal alterations involve different degrees of damage. They could be minor with gap, fragmentation, and/or exchange of chromosome segments or moderate or gross with extensive damage to chromatin matter, nonspecific in nature, and culminating in ultimate lethality to the cell. These alterations necessarily overlap and are directly dose- and time-dependent within the threshold values [see Sharma, 19851.

Such changes, whether in the mitotic index, in chromosome structure or in spindle behavior, indicate that most metals, when administered to higher organisms, are clastogenic at certain doses and durations of treatment and usually act as S- dependent agents.

Second, the initiation and magnitude of the clastogenic effects are associated with a number of factors, including the test system used; effects on osmotic strength; the rate and mode of administration; the uptake, transport, and distribution in the tissues; the vehicle used; and the rates of detoxification, excretion, and interaction, both with foreign and endogenous substances. The variability in the data may also be related to tissue specificity [Newton and Lilly, 19851 and the physiological condition of the organism. The final expression of the effect depends also on the mode of action of the metal itself with the biological macromolecules [see Venugopal and Luckey, 19781.


Discrepant results in the same test system usng the same metallic compounds are very few. The principal conflicting results, unrelated to the difference in test system and nature of the compound, involve the epidemiological studies. Obviously, in such studies, it is difficult to quantify the results and to compare with age- and sex- matched controls. The sample size is usually small and the doses variable. A major factor is the period of culture, since in most cases of occupational exposure to metals, chromosomal aberrations are significantly higher in human leucocytes cultured for 3 days as compared to those cultured for 2 days [see Forni et al, 19801.

Third, general assessment of the data available from mammalian systems shows that the inherent toxicity of the metals within each vertical group of the periodic table, except for Li and Ba, is directly proportional to the increase in atomic weight, electropositivity, and solubility of the metallic cations in water and lipids in relation to conditions within the tissue. The pattern of inherent toxicity, on the basis of horizontal periods in the periodic chart, increases with successive periods. Within a given period, the inherent toxicity of the metal cation decreases progressively from groups I to IV, followed by a gradual increase in that of the metal anion from groups V to VII. In group VIII, both ions have a similar level of toxicity. The increased solubility of the alkali salts of the oxy acids of metals of groups V to VII enhances this inherent toxicity [see Venugopal and Luckey, 1978 for details]. Toxicity is increased with the formation of covalent and coordinate covalent compounds. The heavier metals can form irreversible and stable complexes with biological macromolecules, which change their conformation and biological function.

The information available indicates that the effects of different metals and their compounds on chromosomes and cell division relate well with the relative toxicity of the chemicals, as assessed by physiological and histological criteria.

Fourth, as expected, in plant systems, the solubility of the chemical in water is of much greater importance than it is in mammals. The uptake of heavy metals is also related to endocytosis in cells [see Steinman et al, 1983; Huebner et al, 19851. In general, in plants the cations and the degree of dissociation of metallic salts affects the quantitative induction of aberrations. The effects on chromosomes may or may not be directly due to interaction with DNA but are responsible for creating cellular conditions favoring mitotic disturbances. The metal may interact with the sulphur ligands in the cytoplasm and change the viscosity of the plasma, leading to abnormalities. Most spindle disturbances fall into this category. The metals may also form chelated complexes with cyclic groups or other metals. This complex formation may again alter the cytoplasmic composition and viscosity, thus leading to both clastogenic effects and spindle dysfunction.

From the effects on plant cell division, metals can be classified into three groups, according to a descending order of activity:

i. very strong effects: T1, Cd, Cu, Ag, Cr, Co, Ni, Pt, Pd, Be, Ag, and Au. ii. Very active metals: Zn, Al, Ca, Mn, Fe, Se, Rb, Sr, Sb, Ca, Th, and U. iii. Relatively inactive metals: B, Na, K, Mg, V, As, Mo, Ba, Pb, and Bio. The relative clastogenicity of some metals, as judged from AZZium test were As

< Se < Mo; Co < Ni; Cu < Mn; Pb < Zn < Sr < Ce; Hg < Cd [Von Rosen, 1954; Singh and Sharma, 1980, 1982; Sharma and Sharma, 19601.

Fifth, a comparison of the effects of metal on the chromosomes and the mitotic index in plant and mammalian systems shows that the results are often different. For example, in AZZium cepa, salts of groups lV and VII are significantly mitostatic as


compared to control, while those of I1 and VIII were negligibly so. In Ruttus nowegicus, on the other hand, salts of group V decreased the mitotic index significantly from that of control. Within a group, in general, the mitostatic effect increased with increasing atomic weight [Giri et al, 1980, 19841.

In plant systems, chromosomal abnormalities were significantly increased by exposure to the metallic salts of groups IV and VII but not so with the metallic salts of group III. In animals, the overall increase was significant only with metals of group V. Alterations in the total amounts of DNA, RNA, lipids, and proteins in different organs of mammals, however, were not related to the atomic weight or to the periodic group [Giri et al, 19811. Such differences in clastogenic effects have been observed between different groups of animals, like mammals and fish and between different plants-terrestrial and submerged. The mode of penetration and the metabolism play major roles in causing such differences.

Sixth, the renewed interest in metal pollution has resulted in the evolution of further techniques for assessing the genotoxic/clastogenic potentials of metals. One promising technique, amongst others, is the differential displacement of acridine orange (AO) from DNA through the interaction of metals with DNA as measured by fluorescence polarization [Richardson et al, 19811.

Techniques involving different parameters to study cytotoxicity often tally quite closely. For example, cytotoxic effects, as measured by a cell detachment assay, two different growth assays, cloning efficiency, and cell number after 2 days at con- fluency, were weak after treatment with salts of Al, Zn, and Sn as compared with Cd and Hg as chlorides and K2Cr207. These data were comparable to oral LDS0 values in rat, threshold limit values for human workroom environment, and human eye irritation data [Reinhardt et al, 19851.

Progressive computerization of data, particularly of effects on interchromosomal associations as achieved by Verschaeve et a1 [1985] for mercurials in human lymphocytes may open more avenues for identifying the mode of action of metals.

Seventh, the clastogenic effects of metals are considerably modified by external factors, like nutrition and the presence of other metals and toxic chemicals in the environment. For example, nitrilotriacetic acid trisodium salt (NTA), which is a substitute for polyphosphates in household laundry detergents, was found to increase significantly the frequency of SCE induced by treatment of mammalian cell cultures with insoluble salts of Cd, Hg, Ni, and Pb. The ability of the soluble metal compounds to induce SCE was, on the other hand, not affected [Loprieno et al, 1985; Montaldi et al, 19851.

The clastogenic activity of a metal is also greatly altered, when used in combination with other metals. The action may be antagonistic, synergistic, or simply additive, depending on different variables. Detailed studies on Cd and Pb, carried out in the author’s laboratory, have shown drastic changes in clastogenicity when these metals are used in combination with other metals of the same group or with essential metals [see Sharma, 1985; Sharma et al, 1985; Dhir et al, 1985bl. Selenium, in very small doses, is able to counteract the clastogenicity of Pb in mammalian systems, but no effect is seen in plants [Chatterjee, 1985; Das et al, 1982, 19851. A combination of arsenate and seleno cystine shows interactive effects on crossing-over in Drosoph- ila melanogaster walker and Bradley, 19691. These interactions and their possible causes, however, require a separate detailed review.


ACKNOWLEDGMENTS

The authors are grateful to the Department of Environment, Government of India, for a project under the Man and Biosphere Committee, under which most of the work was carried out; to Dr. Haimanti Dhir for assistance in preparing the manuscript; to Dr. Raymond R. Tice for helpful suggestions for revision; and to Prof. A.K. Sharma, Golden Jubilee Professor and Programme Coordinator, Centre for Advanced Study in Cell and Chromosome Research, for facilities provided.

REFERENCES

Aoki FY, Ruedy J (1971): Severe lithium intoxication: Management with dialysis and report of a possible

Banduhn N, Obe C, Mueller-Oerlinghauson B (1980): Pharmakopsychiatr Neuro-Psychopharmakol

Bariaud A, Bonaly J, Delcourt A, Mestre JC (1980): Various aspects of the toxic effects of cadmium on Euglena gracilis cells. Actual Biochem Mar 2: 135.

Bauchinger M, Dresp J, Schmid E, Englert N, Krause C (1977): Chromosome analysis of children after ecological lead exposure. Mutat Res 56:75-80.

Bauchinger M, Pietruck S, Hall G (1972): Cytogenetic action of lead in human peripheral lymphocytes in vitro and in vivo. Mutat Res 16:407-412.

Bauchinger M, Schmid E (1972): Chromosomenanalysen in Zellkulturen des Chinesischem Hamster nach Applikation von Bleiazetat. Mutat Res 14:95-100.

Bauchinger M, Schmid E, Einbrodt HJ, Dresp J (1976): Chromosome aberrations in lymphocytes after occupational exposure to lead and cadmium. Mutat Res 40:57-62.

Beckman L, Nordenson I, Nordstroem S (1982): Occupational and environmental risks in and around a smelter in Northern Sweden: Three year follow-up of chromosomal aberrations in workers exposed to lead. Hereditas 96:216.

Beek B, Obe G (1974): Effect of lead acetate on human leucocyte chromosomes in vitro. Experientia

Bigalieve AB, Elemesova MS, Turebaev MN, Bigalieva RK (1978): Cytogenetic studies of the mutagenic

Bille PE, Jensen MK, Jensen JPK, Poulsen JC (1975): Studies on the hematologic and cytogenetic effects

Bjilsma JB, de France HF (1976): Cytogenetic investigations in volunteers ingesting inorganic lead. Int

Boshnakova E, Vasileva L (1977): Effect of mercury dichloride on cell division in vivo. Med Biol Probl

Bremner I (1974): Heavy metal toxicities. Rev Biophys 7:75-124. Bruce WR, Heddle JA (1979): The mutagenic activity of sixty-one agents as determined by the

micronucleus, Salmonella and sperm abnormality assays. Can J Genet Cytol2 1:319-334. Bui T, Lindsten J, Nordberg CE (1975): Chromosome analysis of lymphocytes from cadmium workers

and itai-itai patients. Environ Res 9: 187-195. Burgdorf W, Kurnvink K, Cervenka J (1977): Elevated sister chromatid exchange rate in lymphocytes

of subjects treated with arsenic. Hum Genet 36:69-72. Cardarelli N (1985): “Tin as a Vital Nutrient: Implications in Cancer Prophylaxis and Other Physiolog-

ical Processes.” Boca Raton, F1: CRC Press. Casto BC, Meyers J, DiPaolo JA (1979): Enhancement of viral transformation for evaluation of the

carcinogenic or mutagenic potential of inorganic metal salts. Cancer Res 39: 193-198. Chandra S, Harris JR WC, Morrison GH (1984): Distribution of calcium during interphase and mitosis

as observed by ion microscopy. J Histochem Cytochem 32:1224-1230. Chatterjee I (1985): “Effects of Lead on Mammalian Systems.” PhD Thesis, University of Calcutta. Cherian G (1985): “Metallothionein and Metal Toxicity.” Boca Raton, F1: CRC Press. Choie DD, Richter GW (1973): Stimulation of DNA synthesis in rat kidney by repeated administration

teratogenic effect of lithium. Can Med Assoc J 105:847.

13:218-227.

30: 1006-1007.

action of industrial substances. Zdravookr Kaz 8:48-50.

of lithium. Acta Med Scand 198:281-286.

Arch Occup Environ Health 38: 145-148.

5:235.

of lead. Proc SOC Exp Biol Med 142446449.


Choie DD, Richter GW (1978): G2 subpopulation in mouse liver induced into mitosis by lead acetate.

Clain E, Deysson G (1976): Cytotoxicite du cadmium: Etude sur les meristemes radiculaires d’dllium

Claysson DB (1962): “Chemical Carcinogenesis. ” Boston: Little Brown. Columbano A, Ledda GM, Sirigu P, Perra T, Pani P (1983): Liver cell proliferation induced by a single

dose of lead nitrate. Am J Pathol 110:83-88. Cummis LM, Martin JL (1961): Are selenocystein and selenome thionine synthesized in vivo from

sodium selenite in mammals? Biochemistry 6532. Das SK (1982): “Cytological and Cytochemical Effects of Metallic Salts on Mammalian Systems.” PhD

Thesis, University of Calcutta. Das SK, Sharma A, Talukder G (1982): Effects of mercury on cellular system in mammals-a review.

Nucleus 25: 193-230. Das SK, Sharma A, Talukder G (1983): Dose-related clastogenic action of inorganic mercury. Natl Acad

Sci Lett 6: 153-156. Das SK, Giri AK, Sharma A, Talukder G (1985): Effects of mercury-selenium antagonism on mamma-

lian cell division. Cytobios 42:271-276. Das T, Gajra B, Sharma A (1983): Factors influencing the effects of lanthanum salts on mammalian

chromosomes in vivo. Proc XV Int Genet Cong, New Delhi, p 285. De SK, Sharma A (1981): Mutachromosomal effects of lanthanum chloride on mammalian bone marrow.

Curr Sci 50: 189-190. Deasy, D, Bean, CL, Kraynak, A, Armstrong, MA, Galloway, SM, Bradley, MO (1986): Effect of high

osmotic strength on chromosome aberrations, SCEs, and DMA single strand breaks., Environ Mutagen 8 (Suppl. 6): 23.

Deaven LL, Campbell EW (1980): Factors affecting the induction of chromosomal aberrations by cadmium in Chinese hamster cells. Cytogenet Cell Genet 26:251-260.

Degreave N (1969): “Contribution a I’Etude des Mechanisms d’ Action des Agents d’ Alkylation, Modification des Effets du Methane Sulfonate d’Ethyl sur le Chromosome de 1’Orge.” Doctorate Thesis (Univ Liege), 1.

Degreave N (1971): Modification des effets du methane sulfonate d’ethyl on niveau chromosomique, 1. Lesions metalliques. Rev Cytol Biol Veget 34:233-244.

Degreave N (1981): Carcinogenic, teratogenic and mutagenic effects of cadmium. Muta Res 88:115- 135.

Deknudt Gh, Colle A, Gerber GB (1977): Chromosomal abnormalities in lymphocytes from monkeys poisoned with lead. Mutat Res 45:77-83.

Deknudt Gh, Deminatti M (1978): Chromosome studies in human lymphocytes after in v im exposure to metal salts. Toxicology 10:67-76.

Deknudt Gh, Gerber G (1979): Chromosomal aberrations in bone marrow cells of mice given a normal or a calcium deficient diet supplemented with various heavy metals. Mutat Res 68:163-168.

De Serres FJ, Hollaender A (eds) (1980): “Chemical Mutagens, 6, Principles and Methods for Their Detection.” New York: Plenum Press.

Dhir H (1984): “Comparative Effects of Certain Heavy Metals on Cell and Chromosome Division in Higher Organisms. ” PhD Thesis, University of Calcutta.

Dhir H, Sharma A, Talukder G (1985a): Effect of iron on plant and animal systems. J Cytol Genet

Dhir H, Sharma A, Talukder G (1985b): Alteration of cytotoxic effects of lead through interaction with

Dhir H, Talukder G, Sharma A (198%): Comparison of cytotoxic effects of lead following acute and

DiPaolo JA, Casto BC (1979): Quantitative studies of in vitro morphological transformation of Syrian

Douglas GR, Bell RD, Grant CE, Wytsma JM, Bora KC (1980): Effect of lead chromate on chromosome

Dreyfus JC, Schapira G (1964): The metabolism of iron in haemochromatosis. In Gross FG (ed) “Iron

Dube DK, Loeb LA (1975): Manganese as a mutagenic agent during in vitru DNA synthesis. Biochem

Epstein SS, Arnold E, Andrea J, Bass W, Bishop Y (1972): Detection of chemical mutagens by the

Cell Tissue Kinet 11:235-240.

surivum. LCR SOC Biol 170:1151-1155.

20:36-45.

other heavy metals. The Nucleus 28:68-89.

chronic treatments in mammalian systems. Proc Natl Acad Sci India 55B:209-215.

hamster cells by inorganic metal salts. Cancer Res 39: 1008-1013.

aberration, SCE and DNA damage in mammalian cells in v i m . Mutat Res 77: 157-163.

metabolism. ” Berlin: Springer.

Biophys Res Commun 67:1041.

dominant lethal assay in the mouse. Toxic01 Appl Pharmacol23:288-325.


Fiskesjo G (1969): Some results from Alliurn tests with organic mercury halogenides. Hereditas 62:314- 322.

Fiskesjo G (1970): The effects of two organic mercury compounds on human leucocytes in v i m . Hereditas 64: 142- 146.

Flessel CP (1978): In Schrauzer GN (ed): “Inorganic and Nutritional Aspects of Cancer.” New York: Plenum Press, p. 117-128.

Flessel CP, Furst A, Radding SB (1980): A comparison of carcinogenic metals. In Sigel H (ed): “Metal Ions in Biological Systems,” Vol 10. New York: Marcel Dekker, pp 23-54.

Fomenko VN, Gluschenko VI, Katssova LD, Pavlenko GI, Barabanov AA, Makedonskaya RN (1982): Mutagenic and gonadotrophic effect of lead. Gig Tr Prof Zabol 10:38.

Forni A, Sciame A, Bertazzi PA, Alessio L (1980): Chromosome and biochemical studies in women occupationally exposed to lead. Arch Environ Health 35: 139-146.

Fremuth F, Dienstbier 2, Barta J, Sadilkova M, Bradna F (1972): Chromosome aberrations and radioprotection. In: “Advances in Antimicrobial Chemotherapy. ” Baltimore: University Press. Vol2, pp 827-828.

Frieden E, Alles J (1958): Subtle interactions of cupric ion with nucleic acid components. J Biol Chem

Friedrich U, Nielsen J (1969): Lithium and chromosomd abnormalities. Lancet 2:435. Fukina AM, Kudryavtseva TP (1970): In Kruming M ( 4 ) : “Mikroelem med Zhivotnovod.” (USSR)

Ganther HE (1968): Selenotrisulfides: Formation by the reaction of thiols with selenious acid. Biochem-

Garson OM, Latimer NI, Chiu E, Dixon K (1981): Chromosome studies of patients on long-term lithium

Gasiorek K, Bauchinger M (1981): Chromosome changes in human lymphocytes after separate and

Genest P, Villeneuve A (1971): Lithium, chromosomes and mitotic index. Lancet I : 1132. Gerber CB, Leonard A, Jacquet P (1980): Toxicity, mutagenicity and teratogenicity of lead. Mutat Res

Giri AK, Sanyal R, Sharma A, Talukder G (1979): Cytological and cytochemical changes induced

Giri AK, Banerjee R, Talukder G, Sharma A (1980): Mutagenic effects of certain metal toxicants on

Giri AK, Sanyal R, Talukder G, Sharma A (1981): Mutachromosomal effects of some trace elements on

Giri AK, Singh OP, Sanyal R, Sharma A, Talukder G (1984): Comparative effects of chronic treatment

Gitlin D, Cruchand A (1962): Kinetics of iron absorption in mice. J Clin Invest 41:344-350. Glaess E (1955): Untersuchungen Uber die Einwirkung von Schwermetallsalzen auf die Wurzelspitzen-

Glaess E (1956): Die Verteilung von Fragmentation and Achromatischem Stellen auf den chromosomen

Gomez-Arroyo S, Altamirano M, Villalobes-Pietrini R (1981): Sister chromatid exchanges induced by

Grandjean P, Anderson 0 (1982): Toxicity of lead additives. Lancet 2:333-334. Grandjean P, Wulf HC, Niebuhr E (1983): Sister chromatid exchange in response to variations in

Griffith AC (1979): The role of selenium in the chemoprevention of cancer. Adv Cancer Res 29:419. Gruenwedel DW, Friend D (1980): Long-term effects of methyl-mercury (11) on the viability of HeLa

Grunicke H, Bock K, Becker H, Gang V, Schnierda J, Puschendorf B (1973): Cancer Res 33: 1048. Gutierrez M, Sarasquete MC, Establier R (1984): The effect of inorganic mercury on chromosomes of

toad fish. Invest Pesq 48: 181. Haruki K (1983): Studies on the toxicities of metal compounds from the viewpoint of cytotoxicities and

inductivities of sister chromatid exchanges. Osaka-shi Igakkai Zasshi, 32: 193-205 (Jpn).

230~797-804.

Elm Baku.

istry 13:2898.

therapy for psychiatric disorders. Med J Aust 2:37.

combined treatment with divalent salts of lead, cadmium and zinc. Environ Mutagen 3513-518.

76:115-141.

through certain heavy metals on mammalian systems. Natl Acad Sci Lett 2:391-394.

mammalian systems. Proc Indian Acad Sci (Anim Sci) 89:311-331.

mammalian systems. Bionature 1:55-58.

with certain metals on cell division. Cytologia 49:659-665.

mitose von Viciafaba. Z Botanik 43:359.

von Vicia faba nach Behandlung mit Schwermetallsalzen. Chromosoma 8:260.

some chromium compounds inhuman lymphocytes in vitro. Mutat Res 90:425.

occupational lead exposure. Environ Res 32: 199.

S3 cells. Bull Environ Contam Toxic01 25441.


Hasegawa MM, Nishi Y, Ohkawa Y, Inui N (1984): Effects of sorbic acid and its salts on chromosome aberrations, sister chromatid exchanges and gene mutations in cultured Chinese hamster cells. Food Chem Toxicol 22501-507.

HeddIe JA, Hite M, Kirkhart B, Mavournin K, MacGregor JT, Newel1 GW, Salamone MF (1983): The induction of micronuclei as a measure of genotoxicity. A report of the US Environmental Protection Agency Gene-Tox Program. Mutat Res 123:61-118.

Heggtveit NA, Grice HC, Wiberg GS (1970): Cobalt cardiomyopathy: Experimental basis for the human lesion. Pathol Microbiol 35: 110-113.

Herich R (1965): The effects of cobalt on the structure of chromosomes and on mitosis. Chromosoma, 17: 194.

Hessler A (1975): The effects of lead on algae. 11. Mutagenesis experiments on Platymoms subcordifor- mis (Chlorophyta: Volvocales). Mutat Res 31:43-47.

Hino K, Doyama Y, Takahashi E (1984): Evaluation of copper toxicity using seminal roots of rice and effects of the forms of copper compounds on the toxicity. Nippon Dojo Hiryogaku Zasshi 55:50- 54.

Hittelman WN (1982): Premature chromosome condensation. In Hsu TC (ed), “Cytogenetic Assays of Environmental Mutagens.” Totowa, NJ: Allenheld, Osmun, pp 353-384.

Hoegstedt B, Gullberg B, Mark-Vendel E, Mitelman F, Skerfving S (1981): Micronuclei and chromosome aberrations in bone marrow cells and lymphocytes of humans exposed mainly to petroleum vapours. Hereditas 94: 179.

Hollaender A, De Serres FJ (eds) (1971-1980): “Chemical Mutagens: Principles and Methods for Their Detection.” New York: Plenum Press.

Horst WJ, Wagner A, Marschner H (1983): Effect of aluminium on root growth, cell division rate and mineral element content in root of Vigna unquiculata genotype. Z Pflanzenphysiol 109:95- 103.

Hsu TC (1982): “Cytogenetic Assays of Environmental Mutagens.” Totowa, NJ: Allenheld, Osmun. Huebner R, Depta H, Robinson DG (1985): Endocytosis in maize root cap cells. Evidence obtained

Hueper WC, Conway WC (eds) (1964): “Chemical Carcinogenesis and Cancers. ” Springfield, Illinois:

Hurley LS (1978): Teratogenic and chromosomal abnormalities induced by magnesium depletion in

IARC (1980): “Carcinogenesis of Arsenic Compounds.” IARC monograph on Evaluation of Carcino-

ICPEMC Task group 5 (1984): Report on the differentiation between genotoxic and non-genotoxic

ICPEMC Committee 5 (1983): Final report. Mutat Res 123:l-11. Inui N, Nishi Y, Taketomi M, Mori M (1979): Transplacental action of sodium nitrate on embryonic

Jacquet P, Leonard A, Gerber GB (1977): Cytogenetic investigation on mice treated with lead. J Toxicol

Jacquet P, Tachon P (1981): Effects of long term lead exposure on monkey leucocyte chromosomes.

Kalmykova TP, Poloz DD (1978): Chromosome-toxic effect of organo-mercury pesticides. Vestn S-Kh

Kato R (1976): Chromosome breakage associated with organic mercury in Chinese hamster cells in

Kihlman BA (1966): “Action of Chemicals on Dividing Cells.’’ Englewood Cliffs, NJ: Prentice Hall. Kihlman BA (1971): Root tips for studying the effect of chemicals on chromosomes. In Hollaender A

(ed): “Chemical mutagens.” New York: Plenum Press, Vol. 2, p 489. Kilbey BJ, Legator M, Nichols WW, Ramel C (eds) (1984): “Handbook of Mutagenicity Test Proce-

dures,” 22nd ed. New York: Elsevier. King H, Lunford RJ (1950): The relation between the constitution of arsenicals and their action on cell

division. J Chem SOC 8:2086. Kirsch-Volders M, Hens L, Verschaeve L, Alexander A, Driesen M, Poma K, Susanne C (1978):

Modification of human acrocentric associations afrer in vivo exposure to environmental mutagens. Acta Anthropogen 2: 1.

Komczynski L, Nowak H, Rejniak L (1963): Effects of cobalt, nickel and iron on mitosis in the root of the broad bean (Viciufaba). Nature 198: 1016-1017.

using heavy metal salt solutions. Protoplasm 129:214-222.

Thomas.

female rats. Annee Biol 17:241-243.

genic Risks, Vol23. Lyon: IARC, pp 37-141.

carcinogens Pub1 No. 9, Mutat Res 133: 1-49.

cells of Syrian golden hamster. Mutat Res 66: 149-158.

Environ Health 8:619-624.

Toxicol Lett 8: 165-169.

Nauki 5:76.

v i m . Mutat Res 38:340-341.


Kulizewski MJ, Nicholls DM (1983): Translation of mRNA from rat kidney following acute exposure to lead. Int J Biochem 15:657.

Kumaraswamy K, Rajasekarasetty M (1977): Preliminary studies on the effects of cadmium chloride on the meiotic chromosomes. Curr Sci 46:475-478.

Lambert AM, Vantard M, Van Eldik L, De May J (1983): Immunolocalisation of calmodulin in higher plant endosperm cells during mitosis. J Cell Biol97:40a.

Larramendy ML, Popescu NC, DiPaolo JA (1981): Induction by inorganic metal salts of sister chromatid exchanges and chromosome aberrations in human and Syrian hamster cell strains. Environ Mutgen 3597-606.

Latt SA, Schreck RR, Loveday KS, Shuler CF (1982): In Hsu TC (ed): “Cytogenetic Assays of Environmental Mutagens.” Totowa, NJ: Allenheld, Osmun, p 29.

Ledda-Columbano GM, Columbano A, Pani P (1983): Lead and liver cell proliferation: Effect of repeated administration. Am J Pathol 113:315-320.

Ledda GM, Columbano, A,, Perra T, Pani P (1982): Stimulation of rat liver growth by a single administration of lead nitrate. Toxicol Appl Pharmacol 65:478-480.

Lee IP, Dixon RL (1975): Effects of mercury on spermatogenesis studies by velocity sedimentation, cell separation and serail mating. J Pharmacol Exp Ther 194: 171.

Lee T-C, Huang R-Y, Jan KY (1985): Sodium arsenite enhances the cytotoxicity, clastogenicity and 6- thioguanine-resistant mutagenicity of UV light in Chinese hamster ovary cells. Mutat Res 148:83- 89.

Leonard A (1981): In: “Proc I11 International Congress of Environmental Mutagenesis,” New York: Alan R. Liss, Inc. p 57.

Leonard A, Deknudt G , Debackere M (1974): Cytogenetic investigations in leucocytes of cattle intoxi- cated with heavy metals. Toxicology 2: 269-273.

Leonard A, Deknudt G, Gilliavod N (1975): Genetic and cytogenetic hazards of heavy metals in mammals. Mutat Res 29:280-281.

Leonard A, Gerber GB, Jacquet P (1981): Carcinogenicity, mutagenicity and teratogenicity of nickel. Mutat Res 87:l-15.

Leonard A, Lauwerys RR (1980a): Carcinogenicity, teratogenicity and mutagenicity of arsenic. Mutat Res 75:49-62.

Leonard A, Lauwerys PR (1980b): Carcinogenicity and mutagenicity of chromium. Mutat Res 76:227- 239.

Leonard A, Linden G , Gerber GB (1972): Etude chez les souris, des effects genetiques et cytogenetiques d’une contamination par le plomb. In Barth D, Berlin A, Engel R, Recht P, Smeets J (eds): “International Symposium on Environ Health Aspects of Lead” Amsterdam: Luxembourg, p 303.

Lessler MA, Walters MI (1973): Erythrocyte osmotic fragility in the presence of lead or mercury. Proc SOC Exp Biol Med 142548-553.

Levan A (1945): Cytological reaction induced by inorganic salt solution. Nature 156:751. Liquier-Milward J (1951): Evidence of a complex compound of cobalt with a purine base (adenine).

Nature 167: 1068. Lo KW, Koropatnick J, Stich HF (1978: The mutagenicity and cytotoxicity of selenite, activated selenite

and selenate for normal and DNA repair-deficient humant fibroblasts. Mutat Res 49:305-312. Loprieno N, Boncristiani G, Venier P, Montaldi A, Majone F, Bianchi V, Paglialunga S, Levis AG

( 1985): Increased mutagenicity of chromium compounds by nitrolotriacetic acid. Environ Muta- gen 7: 185-200.

Luca D, Raileanu L, Luca V and Duda R (1985): Chromosomal aberrations and micronuclei induced in mouse and rat bone marrow cells by sodium nitrate. Mutat Res 155:121-125.

Luckey TD (1975): Hormology with inorganic compounds. Environ Qua1 Saf Suppl 1 :81-103. Mailhes JB ( 1984): Methylmercury-induced cytogenetic damage in Syrian hamster bone marrow cells. J

Maki-Paakkanen J, Sorsa M, Vainio H (1981): Chromosome aberrations and sister chromatid exchanges

Malik CP, Basra AS, Ahluwalia KS (1985): Modulation of plant cellular functions by Ca2+-Calmodulin

Martin GR, Brown KS, Matheson DW, Lebowitz H, Singer L, Ophaug R (1979): Lack of cytogenetic

Martin SE, Schillaci M (1984): Inhibitory effects of selenium on mutagenicity. J Agric Food Chem

Am Coli Toxicol 3:295-301.

in lead-exposed workers. Hereditas 94:269-275.

complex. Biologia 1 : 1- 12.

effect in mice or mutations in Sdmoneh receiving sodium fluoride. Mutat Res 66: 159- 167.

32:426-433.


Mathur AK, Dikshith TSS, Lal MM, Tandon SK (1978): Distribution of nickel and cytogenetic changes

McLean JRN, Blakey DH, Douglas GR, Kaplan JG (1983a): The effect of stannous and stannic (tin)

McLean JRN, Birnboim HC, Pontefact R, Kaplan JG (1983b): The effect of tin chloride on the structure

Miller JA, Miller EC (1976): Carcinogens occurring naturally in foods. Fed Proc 35: 1316. Mitra A (1984): “Antagonistic and Synergistic Effects of Some Metals of the Group I1 on Genetic

Mitra S (1985): “Mercury in the ecosystem.” Aedermanusdorf CH-4711, Trans Tech Publ. Miura K, Nakada S, Suzuki K, Irnura N (1979): Ultrastructural studies in the cytotoxic effects of

mercuric chloride on mouse glioma. Ecotoxicol Environ Safety 3:352. Monakhova MA, Melukhina LW, Steppe ZG (1976): The different sensitivities of chromosomes and

interchromosomal associations to the mutagenic action of K1 in connection with the nature of the contromeric association system. Vestn Mosk Univ Ser 6 Biol 1:57-62.

Montaldi A, Zentilin L, Venier P, Cola I, Bianchi V, Paglialunga S, Levis AG (1985): Interaction of nitrolotriacetic acid with heavy metals in the induction of sister chromatid exchanges in cultured mammalian cells. Environ Mutagen 7:381-390.

Moutschen-Dahmen J, Moutschen-Dahmen M, Degraeve N (1965): Modified effects of ethylmethane sulfonate (EMS) at the chromosome level. Symp Mechanism of Mutation and Inducing Factors, Prague, p 397.

Mukherji S, Maitra P (1976): Toxic effects of lead on growth and metabolism of germinating rice (Oryzu sutivu L.) seeds and on mitosis of onion (Allium cepa L.) root-tip cells. Indian J Exp Biol 14519- 521.

Mukherjee A, Sharma A, Talukder G (1984): Effects of cadmium on cellular systems in higher organisms. The Nucleus 27:121-139.

Mukherjee A, Sharma A, Talukder G (1985a): Comparative cytotoxic effects of cadmium on plants and animals. Trends Plant Res 2:355-361.

Mukherjee A, Sharma A, Das AK (1985b): Estimation of cadmium in biological tissues by atomic absorption spectrophotometer-a new reagent. Ind J Exp Biol23:663-664.

Muramatsu S, Hanada H, Himeno K (1980): Effects of cadmium chloride and X-rays on chromosome aberration induction in bone marrow cells and spermatogonia of mice Radiobiol Equivalents Chem Pollut, Proc Advis Group Meet, 1977(Publ 1980), p 61.

Naganuma A, Saloh M, Imura N (1984): Effect of copper pretreatment on toxicity and antitumor activity of cis-diamine-dichloroplatinum in mice. Res Commun Chem Pathol Pharmacol46:265-274.

Nagymajteryi L, Selypes A, Berensci G (1984): Mutagenic and fetotoxic effect of aerogenic lead exposure on mice. Egeszsegtudomany 28:53.

Nakamuro K, Yoshikawa K, Sayato Y, Kurata H, Tonomura M, Tonomura A (1976): Studies of selenium related compounds, V. Mutat Res 40:177-184.

Nakanuro K, Sayato Y (1981): Comparative studies of chromosomal aberrations induced by trivalent and pentavalent arsenic. Mutat Res 88:73-80.

Natarajan AT, Obe G (1980): Screening of human populations for mutations induced by environmental pollutants: Use of human lymphocyte system. Ecotoxicol Environ Safety 4:468-481.

Newton MF, Lilly U (1986): Tissue-specific clastogenic effects of chromium and slenium salts in vivo. Mutat Res 169:61-69.

Nishimura M, Umeda M (1979): Induction of chromosomal aberrations in cultured mammalian cells by Ni compounds. Mutat Res 68:337.

Noda M, Takano T, Sakurai H (1979): Mutation activity of selenium compounds. Mutat Res 66:175- 179.

Nordensen I, Beckman G , Beckman L, Nordstroem S (1978a): Occupational and environmental risks in and around a smelter in Northern Sweden 11. Chromosomal alterations in workers exposed to arsenic. Hereditas 88:47-50.

Nordensen I, Beckman G, Beckman L, Nordstroem S (1978h): Occupational and environmental risks in and around a smelter in Northern Sweden, IV. Chromosomal aberrations in workers exposed to lead. Hereditas 88:263-267.

Nordensen I, Nordstroem S, Sweins A, Beckman L (1982): Chromosomal aberrations in lead-exposure workers. Hereditas 96:265.

in poisoned rats. Toxicology 10: 105.

chloride on DNA in Chinese hamster ovary cells. Mutat Res 119:195-201.

and function of DNA in human white blood cells. Chem-Biol Interact 46: 189-200.

Systems. ” PhD Thesis, University of Calcutta.


Norppa H, Westermarck T, Laasonen M, Knuutila K, Knuutila S , (1980a): Chromosomal effects of sodium selenite in vivo. Aberrations and sister chromatid exchanges in human lymphocytes. Hereditas 93:93-96.

Norppa H, Westermarck T, Oksanen A, Rimaila-Parnanen E, Knuutila S (1980b): Chromosomal effects of sodium selenite in vivo. 11. Aberrations in mouse bone marrow and primary spermatocytes. Hereditas 93:97-99.

Norppa H, Westermarck T, Knuutila S (1980~): Chromosomal effects of sodium selenite in vivo. 111. Aberrations of sister chromatid exchanges in Chinese hamster bone marrow. Hereditas 93: 101- 105.

Nriagu JO (ed) (1978): “Biogeochemistry of Lead in the Environment.” Amsterdam: ElsevierlNorth- Holland.

Nriagu JO (ed) (1979): “Biogeochemistry of Mercury in the Environment.” Amsterdam: Elsevier/ North-Holland.

Nriagu JO (ed) (1980): “Cadmium in the Environmental 1. Ecological Cycling.” New York: Wiley Interscience.

Obe G, Beek B, Dudin G (1975): Some experiments on the action of lead acetate on human leucocytes in vitro. Mutat Res 29:283.

Ohno H, Hanaoka F, Yamada M (1982): Inducibility of sister chromatid exchanges by heavy metal ions. Mutat Res 104:141-145.

Ono H, Ono P, Wada 0 (1978): Effects of cadmium on some enzyme activities of rat liver with special reference to DNA and protein synthesis in the nuclei. Ind Health 16:73.

Oppenheim JP, Fishbein WW (1965): Induction of chromosome breaks in cultured normal human leucocytes by potassium arsenite, hydroxyurea and related compounds. Cancer Res 25: 1980.

O’Riordan ML, Evans HJ (1974): Absence of significant chromosome damage in males occupationally exposed to lead. Nature 247:50-53.

O’Riordan ML, Hughes EG, Evans HJ (1978): Chromosome studies on blood lymphocytes of men occupationally exposed to cadmium. Mutat Res 58:305-3 11.

Paton GR, Allinson AC (1972): Chromosome damage in human cell cultures induced by metal salts. Mutat Res 16:332-336.

Petres J, Schmid-Ulrich K, Wolf U (1970): Chromosomen aberratineu an menschlichen lymphozyten bei chromischen Arsenschaden. Deut Med Wschr 95:79.

Popescu HI, Negru L, Lancranjan T (1979): Chromosomal aberrations induced by occupational exposure to mercury. Arch Environ Health 34:461-463.

Quazi OH, Madahar C, Yuceoglu AM (1980): Temporary increase in chromosome breakage in an infant prenatally exposed to lead. Hum Genet 53:201.

Rai LC, Gaur JP, Kumar HD (1981): Phycology and heavy metal pollution. Biol Rev 56:99-151. Rainaldi G, Colella CM, Piras A, Mariana I (1982): Thioguanine resistance, ovabain resistance and

sister chromatid exchanges in V79/AP4 CHO treated with potassium dichromate. Chem Biol Interact 42:45.

Ramaya L, Pomerantzeva M (1977): Investigation of cadmium chloride mutagenic effect of germ cells of male mice. Genetika 1359.

Ramel C (1969): Methylmercury as a mitosis disturbing agent. 3 Jpn Med Assoc 61: 1072-1076. Rasrnussen H, Barrett PQ (1984): Calcium messenger systems-an integrated review. Physiol Rev

Rathore HS, Swamp H (1982): Toxicity of lead nitrate to Chirunomus sp. larvae: A cytogenetic investigation. Pak J Zoo1 14: 118-121.

Ravindran PM (1971): Chromosomal abnormalities induced by thallium compounds in Allium cepa. J Ind Bot SOC 50:337.

Ray JH, Altenburg LC (1980): Dependence of the sister-chromatid exchange (SCE)-inducing abilities of inorganic selenium compounds on the valence state of selenium. Mutat Res 78:261-266.

Ray JH, Altenburg LC (1982): Sister chromatid exchange induction by sodium selenite: Plasma protein band selenium is not the active sister-chromatid exchange-inducing metabolite of sodium selenite. Mutat Res 102:285-296.

Ray JH, Altenburg LC, Jacobs MM (1978): Effect of sodium selenite and methyl methane-sulfonate on N-hydroxy-2-acetyl aminoff uorene coexposure on sister chromatid exchange production in human whole blood cultures. Mutat Res 47:359-368.

Reinhardt CA, Pelli DA, Sandvold M (1985): Cell detachment and growth of fibroblasts as parameters for cytotoxicity of inorganic metal salts in vitro. Cell Biol Toxic01 1:33-43.

64:938-984.


Richardson CL, Verna J, Schuzman G, Shipp K, Grant AD (1981): Metal mutagens and carcinogens effectively displace acridine orange from DNA as measured by fluorescence polarization. Environ Mutag 3545.

Robinson SH, Costa M (1982): The induction of DNA strand breakage by nickel compounds in cultured CHO cells. Cancer Lett 15:35.

Roederer G (1984): On the toxic effects of tetraethyl lead and its derivatives on the chrysophyte Poterioochromonas malhamensis V: Electron microscope studies. Environ Exp Bot 24: 17.

Rohr G, Bauchinger M (1976): Chromosome analysis in cell cultures of the Chinese hamster after application of cadmium sulfate. Mutation Res 40: 125-130.

Rosas I, Carbajal ME, Gomez-Arroyo S, Belmont R, Villalobos-Pietrini R (1984): Cytogenetic effects of cadmium accumulation on water hyacinth (Eichhorniu crassipes). Environ Res 33:386.

Roschin IV (1967): Toxicology of vanadium compounds used in modem industry. Gig I Sonit 32:26-34. Rossman TG, Stone D, Molina M, Troll W (1980): Absence of arsenite mutagenicity in E. coli and

Chinese hamster cells. Environ Mutagen 2:371-379. Rossner P, Sram RJ (1978): Mutagenic effect of sodium arsenite in Chinese hamster cell line. Biol

Zentralbl 97:411-477. Roux SJ, Slocum RD (1982): Role of calcium in mediating cellular functions in important for growth

and development in higher plants. In (ed): Cheung WY “Calcium and Cell Function” Vol 3. New York: Academic, p 408.

Ruben TR, Sunderlingam M (1983): Lead ion binding and transfer RNA chain hydrolysis in phenylala- nine t-RNA. Biomol Struct Dyv 1:639-646.

Ruposhev AR (1976): Cytogenetic effect of heavy metallions on Crepis capiflaris L. Seeds. Genetika

Ruposhev AR, Garina KP (1976): Mutagenic effect of cadmium salts. Tsitol Genet 10:437. Ruposhev AR, Garina KP (1977): Modification of the mutagenetic effect of ethylenimine by cadmium

nitrate in Crepis capiflaris. Genetika 13:32. Saha AK, Sircar S (1983): Effect of calcium lactate on grasshopper spermatocytic chromosomes. Abst

Proc XV Int Congr Genetics 13:32. Saha AK, Sircar S (1983): Effect of calcium lactate on grasshopper spermatocytic chromosomes. Abst

Proc XV Int Congr Genetics, New Delhi, p 324. Saksoong P, Campiranon Am (1983): Genotoxicity of heavy metals, I. Zinc. Abst Proc XV Int Congress

Genetics, New Delhi, p 324. Sanyal R, Giri AK, Talukder G, Sharma A (1980): Effects of cobalt and nickel on mammalian cellular

systems. Biol Bull India 2:85-90. Sayato Y, Nakamuro K (1980): Chromosomal aberration in cultured humanlympocytes induced by

simultaneous treatment with mercury compounds and selenium compounds. Eisei Kagaku 26:99. Schwanitz G, Gebhart E, Rott HD, Schaller KH, Essing HG, Lauer 0, Prestele H (1975): Chromosome

investigations in subjects with occupational lead exposure. Dtsch Med Wochenschr 100: 1007- 1011.

Sen P, Costa M (1985): Induction of chromosomal damage in Chinese hamster ovary cells by soluble and particle Ni compounds: Preferential fragmentation of the heterochromatic long arm of the X- chromosome by carcinogenic NiS particles. Cancer Res 45:2320-2325.

Sentein P (1967): Action derives du Selenium (Selenates et Selenites) comparee a celle d’acides divers

12:37-43.

(Crotonique, acetique, citrique et phosphorique) Sur les mitoses de segmentation. Chromosoma 23:95.

Shakhmaev NK (1984): Survival of Limnaeu stagnalis in the presence of copper ions. Vestn Zoo1 5:79. Shamberger RJ (1974): Antioxidants and cancer, 111. In Hoekstra WG, Suttie JW, Ganther HE, Mertz

W (eds): “Trace Element Metabolism in Animals,” Baltimore: University Park Press, pp 593- 597.

Sharma A (1984): “Environmental Chemical Mutagenesis.” Persp Rep Ser 6, pp 1-53. New Delhi: Golden Jubilee Publications, Indian National Science Academy.

Sharma A (1984b): Genetical effects of metallic salts on eukaryotic systems. In Manna GK, Sinha U (eds): “Perspective in Cytology and Genetics.” Delhi: Hindasia, Vol4, pp 2-24.

Sharma A (1984~): “The Chromosomes.” New Delhi: Oxford and IBH. Sharma A (1985): “Clastogenic Action of Metal Pollution in the Indian Context.” Presidential address

in the Biological Sciences, The National Academy of Sciences, India, Ann Gen Meeting, Nov 3- 5, Gwalior, pp 1-9.


Sharma A, Mukherjee A, Talukder G (1985): Modification of cadmium toxicity in biological systems by other metals. Curr Sci 54:539-549.

Sharma AK, Sharma A (1960): Spontaneous and induced chromosome breaks. Int Rev Cytol 10: 101- 136.

Sharma AK, Sharma (1980): “Chromosome Techniques-Theory and Practice,” 3rd Ed. London: Butterworths.

Sharma AK, Sharma A (eds) (1981): “Impact of Development of Science and Technology on Environ- ment. ” Calcutta: Indian Science Congress Association Focal Theme Publ.

Shevchenko VV, Grinikh LI, Cheltsov PA, Ivanov VB, Shchelokov RN (1983): Relationship between cytogenetic effect of platinum (11) complexes and their structure. Mutat Res 122:329-335.

Shimada T, Watanabe T, Endo A (1976): Toxic effect of trace elements on the reproduction of mice and rats. Arch Environ Health 23: 102.

Shirachi DY, Johansen MG, McGowan JP, Tu SH (1983): Tumorigenic effect of sodium arsenite in rat kidney. Proc W Pharmacol SOC 26:413-415.

Shiraishi Y, Kurahashi H, Yoshida TH (1972): Chromosomal aberrations in cultured human leucocytes induced by cadmium sulfide. Proc Jpn Acad 48: 133-137.

Shiraishi W, Yoshida TH (1972): Chromosomal abnormalities in cultured leucocyte cells from Itai-itai disease patients. Proc Jpn Acad 48:248-251.

Shiramizu M, Kaku S, Shimojo N, Sano K (1976): Health effects of long-term diets in cats. I The dose response relation between the amount of tuna consumed and the numerical aberration of lymphocyte chromosomes. Nippon Eiseigaku Zasshi 31 :445.

Sideris EG, Petraki M, Kalfas C (1981): Cu2+ as an environmental mutagenic agent. Abstract paper presented at 10th Meeting Mutat Res 85(4):303, EMS, Athens

Sigel H (ed) (1980-1984): “Metal ions in biological systems, 10-15. New York: Marcel Dekker. Singh A, Bhargava I (1983): Chromosomal damage as a result of exposure to chromium fumes in

industrial workers. Abstr Proc XV Int Congr Genet, New Delhi, p 332. Singh OP (1979): “Effects of Certain Chemical Pollutants on Plant Chromosomes.” PhD Thesis

submitted to the University of Calcutta. Singh OP, Sharma A (1980): Effects of certain metallic pollutants in plant genetic systems-a review.

The Nucleus, 23:15-29. Singh OP, Sharma A (1981): Radiomimetic effects of some metallic salts. In Manna GK, Sinha U (eds):

“Perspective in Cytology and Genetics,” Delhi: Hindasia Publ, Vol 3, pp 489-492. Singh OP, Sharma A (1982): Effects of mercury, cadmium and lead on plant chromosomes. In Sen SP

(ed): “Recent Developments in Plant Sciences” New Delhi: Prof SM Sircar Memorial Vol, Today and Tomorrow, pp 305-3 12.

Skerfving S, Hansson K, Lindsten J (1970): Chromosome breakage in humans exposed to methyl mercury through fish consumption: Preliminary communications. Arch Environ Health 2 1 : 133- 139.

Skerfving S , Hansson K, Mangs C, Lindsten J, Ryman N (1974): Methylmercury-induced chromosome damage in man. Environ Res 733-98.

Srivastava S (1985): “Effects of Li on Eukaryotic Cell Division.” Thesis submitted for PhD degree, University of Calcutta.

Stadnicka A (1978): Inhibitory effect of mercury nitrate on mitotic activity of rat kidney tubular cells in tissue culture. Bull Acad Pol Sci, Ser Sci Biol26:207.

Steinman RM, Mellman IS, Mueller WA, Cohn ZA (1983): Endocytosis and the recycling of plasma membrane. J Cell Biol 96:l.

Stella M, Rossi R, Martinucci GB, Rossi G , Bonafante A (1979): BudR as a tracer of the possible mutagenic activity of Pb2+ in human lymphocyte cultures. Biochem Exp Biol 14:221.

Stella M, Montaldi A, Rossi R, Rossi G , Levis AG (1982): Clastogenic effect of chromium on human lymphocytes in vivo and in vitro. Mutat Res 101: 151-164.

Stevenson AJ, Macero S, Senghal RL (1977): Influence of lead on hepatic, renal and pulmonary nucleic acids, polyamines and cyclic adenosino 3’:5’ monophosphate metabolism in neonatal rats. Toxic01 Appl Pharmacol40: 161.

Stokinger HE (1967): In Patty FA (ed): “Industrial Hygiene and Toxicology,” 2nd ed. New York: Interscience, Vol 2 pp 1171-1182.

Sudakova AI, Shevchenko ZH T, Nosova LI (1983): Effect of prolonged exposure to lead on peripheral blood and bone marrow cells in the albino rat. Tsitol Genet 17:3-7.


Sugimura T, Kondo S, Takebe H (eds) (1982): “Environmental Mutagens and Carcinogens.” Tokyo:

Sunderman FW (1979): Mechanism of metal carcinogenesis. Biol Trace Elements Res 1:65-86. Sutou S, Yamamoto K, Sendots H, Sugiyama M (1980): Toxicity, fertility, teratogenicity and dominant

lethal tests in rats administered cadmium subchronically. 11. Fertility, teratogenicity and dominant lethal tests. Endotoxicol Environ Safety 4:51.

Swierenga SHH, Basrur PK (1968): Effect of nickel on rat embryo muscle cells. Lab Invest 19:663- 675.

Thomson EJ, Kilanowski FM, Perry PE (1985): The effect of fluoride on chromosome aberration and sister chromatid exchanges frequencies in cultured human lymphocytes. Mutat Res 144: 89-92.

Timson J, Price DJ (1971): Lithium and mitosis. Lancet 2:93. Torre R de la, Krompotic E (1975): In vivo and in vitro effects of lithium on human chromosomes and

cell replication. Teratology 13: 131. Tribedi S, Biswas AK, Koner D, Ray S, Dey K (1984): Effects of cobalt (HI) complexes of Schiff bases

on root tip mitosis. Int J Environ Studies 22:241. Tsuda H, Kato K (1977): High rate of endoreduplication and chromatid aberrations in hamster cells

treated with sodium nitrate in vivo. Mutat Res 56:69. Tsutsui T, Suzuki N, Ohmori M, Maizumi H (1984): Cytotoxicity, chromosome aberrations and

unscheduled DNA synthesis in cultured human diploid fibroblasts induced by sodium fluoride. Mutat Res 139:193-198.

Umeda M, Nishimura N (1979): Inducibility of chromosomal alterations by metal compounds in cultured mammalian cells. Mutat Res 67:221-229.

Umeda M, Saito K, Hirose K, Saito M (1969): Cytotoxic effects of inorganic phenyl and alkylmercuric compounds on HeLa cells. Jpn J Exp Med 39:47-58.

Vanlina EN, Anikieva ID, Kogan IG (1978): Effect of cadmium ion on cell division in the root meristem of Crepis capitluris L. Tsitol Genet 12:497.

Vendel EM, Hoegstedt B, Skerfving S, Mitelman F (1981): Location of chromosome aberrations in bone marrow cells of individuals exposed to petroleum vapours. Hereditas 95:235.

Venier P, Montaldi A, Majone F, Bianchi V, Levis AG (1982): Cytotoxic, Mutagenic and clastogenic effects of industrial chromium compounds. Carcinogenesis 3: 1331-1338.

Venier P, Montaldi A, Busi L, Gava C, Zentillin L, Tecchio G , Bianchi V, Levis AG (1985): Genetic effects of chromium tannins. Carcinogenesis 6: 1327.

Venugopal B, Luckey TD (1978): “Metal Toxicity in Mammals,” Vols 1, 2. New York: Plenum Press. Verschaeve L, Susanne C (1978): Chromosome banding produced after HgC12 treatment in culture. Acta

Anthropogen 2: 1-8. Verschaeve L, Kirsch-Volders M, Susanne C, Groetenbriel C, Haustermans R, Lecomte A, Roossels D

(1976): Genetic damage induced by occupationally low mercury exposure. Environ Res 12:306- 316.

Verschaeve L, Kirsch-Volders M, Hens L, Susanne C (1978): Chromosome distribution studies in phenyl mercury acetate exposed subjects and in age-related controls. Mutat Res 57:335-347.

Verschaeve L, Driesen M, Kirsch-Volders M, Hens L, Susanne C (1979a): Chromosome distribution studies after inorganic lead exposure. Hum Genet 49:147-158.

Verschaeve L, Kirsch-Volders M, Susanne C (1984): Mercury-induced segregational errors of chromosomes in human lymphocytes and in Indian muntjac cells. Toxic01 Lett 21:247-253.

Verschaeve L, Kirsch-Volders M, Hens L, Susanne C (1985): Chromosome distribution studies in phenyl mercury acetate exposed subjects and in age-related controls. Mutat Res 57:335-347.

Verschaeve L, Tasignon JP, Lefevre M, DeStoop P, Susanne C (1979b): Cytogenetic investigation on leukocytes of workers exposed to metallic mercury. Environ Mutagen 1 :259-268.

Vilkina GA, Pomerantzeva MD, Ramaya LK (1978): Lack of mutagenic effect of cadmium and zinc salts in somatic and germ mouse cells. Genetika 14:2212-2214.

Von Rosen G (1954a): Breaking of chromosomes by the action of elements of the periodical system and some other principles. Hereditas 40:258.

Von Rosen G (1954b): Radiomimetic reactivity arising after treatment employing elements of the periodical system. Socker Handlinger I1 8: 157.

Von Rosen G (1957): Mutations induced by the action of metal ions in Pisurn. Hereditas 43544. Voroshilin SI, Plotko EG, Fink TV, Nikiforova VYa (1978): Cytogenetic effect of inorganic and acetate

compounds of tungsten, zinc, cadmium and cobalt on animal and human somatic cells. Tsitol Genet 12:241-243.

University of Tokyo Press, and New York: Alan R Liss.


Wagatsuma T (1983): Characterization of absorption sites for aluminium in the roots. Soil Sci Plant Nutr

Wagner GJ, Trotter MM (1982): Inducible cadmium binding complexes of cabbage and tobacco. Plant Physiol69:804.

Wakswik H, Boysen M, Hoegtveit AC (1984): Increased incidence of chromosomal aberrations in peripheral lymphocytes of retired nickel workers. Carcinogenesis 5: 1525- 1527.

Wakswik H, Boysen M, Hoegtveit AC (1984): Increased incidence of chromosomal aberrations in peripheral lymphocytes of retired nickel workers. Carcinogenesis 5: 1525- 1527.

Walker GWR, Ting KP (1967): Effects of selenium on recombination in barley. Can J Genet Cytol 9:314.

Walker GWR, Bradley AM (1969): Interacting effects of sodium monohydrogen arsenate and seleno cystine on crossing over in Drosophilu mehogaster. Can J Genet Cytol 11:667.

Wan B, Christan RT, Soukup SW (1982): Studies of cytogenetic effects of sodium arsenicals on mammalian cells in vitro. Environ Mutagen 4:493-498.

Watanabe T, Shimada T, Endo A (1979): Mutagenic effects of cadmium on mammalian oocyte chromosomes. Mutat Res 67:349.

Watanabe T, Shimada T, Endo A (1982): Effects of mercury compounds on ovulation and mitotic and meiotic chromosomes in female golden hamsters. Teratology 25:381-384.

Webb M (ed) (1979) “The Chemistry, Biochemistry and Biology of Cadmium.” Amsterdam: Elsevier/ North-Holland.

Wen WN, Lieu LT, Chang HJ, Wuu SW, Yau ML, Jan KY (1981): Baseline and sodium arsenite-induced sister chromatid exchanges in cultured lymphocytes from patients with blackfood disease and healthy persons. Hum Genet 59:201-203.

Wiberg GS, Munro IC, Meranger JC, Morison AB, Grice HC, Heggtveit NA (1969): Effects affecting cardiotoxicity of cobalt. Clintoxicology 2:257-272.

Wojciechowska B, Kocik H (1983): Effect of AIC12 and SO4 on the root meristem of Mciafabu L. Acta

Wolff S (ed) (1982): “Sister chromatid Exchange.” New York: John Wiley. Wyrobek AJ, Bruce WR (1978): The induction of sperm cell abnormalities in mice and humans. In

Zanzoni F, Jung EG (1980): Arsenic elevates the sister chromatid exchanges (SCE) rate in human

Zatsepina OV, Polyakov VY, Chentsov YS (1983): Electron microscope study of chromonema and

29~499-5 16.

SOC Bot POI 52: 185-195.

Hollaender A (ed): “Chemical Mutagens,” Vol5. New York: Plenum Press, p 237.

lymphocytes in v i m . Arch Dermatol Res 267:91-95.

chromomeres in mitotic and interphase chromosomes. Tsitologiya 25: 123-129.

effects of metals on chromosomes of higher organisms

Documents