interaction of lead

8/2/2019 Interaction of Lead

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INTERACTION OF LEADWITH PESTICIDE IN

HUMAN POINT OF VIEW

PRESENTED BY

HARNEET KAUR

L-2011-V-87-M


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Definition of pesticide

a pesticide is any substance or mixture ofsubstances intended for preventing,

destroying, repelling, or mitigating any pest.

a pest is any harmful, destructive, or

troublesome animal, plant or microorganism.


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Reasons for concerns about pesticides in

environmental quality and human health

result from:

persistence

transport

toxicity


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Persistence is one determiner of themagnitude of residues in soil or on foods.

Persistence can be represented by determininga pesticide's half-life. Half-lives in soil forseveral years

Breakdown products (metabolites) canthemselves be persistent & toxic


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Ranking persistence

(in a very general way):

Longest Inorganics such as lead arsenate

Chlorinated hydrocarbons

Medium Organophosphates

Carbamates

Pyrethroids

Neonicotinoids

Shortest Botanicals

Soaps

Microbials


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Transport

Residues may be carried away from

application sites, often to unwanted

destination


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lead arsenate based pesticide, was usedextensively to control agricultural pests in fruitorchards until the late 1950s.

Direct pesticide exposure occurred with workerswho mixed or applied the chemicals in theorchards. Indirect exposure can occur with thepesticide residues found in the soil today.

The pesticide residues bind tightly to the surfacesoil layer, where they have remained for decades.As a result, the residues may pose a human health

risk when the land changes from agriculture toother uses. For example, lead arsenatecontaminated soil can be hazardous if childrencontinually play in it.


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Both lead and arsenic can be toxic at high

concentrations in soils.

The naturally occurring soil levels of these metals

are not considered toxic. However, in existing and

former orchards, lead arsenate pesticides have

caused soil levels to become a health concern.

Historically, apple orchards required more pesticide

applications than cherry orchards. Therefore, higher

amounts of lead and arsenic are found in former

apple orchard


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Exposurelead arsenate pesticides in former orchard soils

involves contact with the bare soils. Some commonactivities that may increase exposure are:

Gardening or digging in the soil,

Children playing in contaminated soil (particularly if

not washing after play),

Eating without first washing hands and face afterdigging in soils, and

Eating unwashed vegetables grown in the soilsUnder some condition pesticide may also

contaminate the underground water specially people

living near orchard


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Other Sources of Lead

Exposure

Residue of leaded gasoline

Lead smelting and recycling

Solder (Pb + Sn), welding (minor)

Metalworking

Ammunition and explosives

Exterior paints

Kohl and certain herbal remedies


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Exposure of Lead


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Absorption of Lead:

Ingestion Major source of lead exposure forchildren

Inhalation Primary route of exposure for adults

Dermal contact Plays a role for exposure to

organic lead among workers, but is notconsidered a significant pathway for the generalpopulation.

Endogenous Exposure Once absorbed, lead

may be stored for long periods in mineralizingtissue ( i.e., teeth and bones)releasedagain into the bloodstream in times of calciumstress ( e.g. , pregnancy, lactation,

osteoporosis), or calcium deficiency


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Distribution of

Lead 95% long bones.Binds into matrix.

Released during

osteolysis.

4% brain,liver, kidneys.

1% blood.

Crosses placenta, foetal

BBB is open


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Who Is at Risk of Lead

Exposure?:Children

Adults mainly occupational exposure Auto

repairers, Battery manufacturers, Bridge

reconstruction workers, Construction workers,

Glass manufacturers, Lead manufacturing

industry, Plastic manufacturers, Police

officers, Printers, Rubber productmanufacturers, Steel welders or cutters

Pregnant Women and Developing Fetuses


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Biologic Fate of Lead?:

Adults typically absorb up to 20% of ingested lead. Mostinhaled lead in the lower respiratory tract is absorbed.Most of the lead that enters the body is excreted in urine orthrough biliary clearance (ultimately, in the feces).Inorganic lead is not metabolized in the liver. Nearly allorganic lead that is ingested is absorbed. Organic leadcompounds are metabolized in the liver

Absorbed lead that is not excreted is exchanged primarily

among three compartments Blood Mineralizing tissues(bones and teeth), which typically contain the vast majorityof the lead body burden Soft tissue (liver, kidneys, lungs,brain, spleen, muscles, and heart)


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Lead toxicity can affect every organ

system including

Nervous system

Renal system

Blood Endocrine glands

GIT

Reproductive system


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Neurological Effects:

The nervous system is the most sensitive target of lead

exposure.

In children: Neurological effects of lead in children

have been documented at exposure levels once thoughtto cause no harmful effects (


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Neurological effect in adult

Neurological and behavioral effects in lead-

exposed workers with BLLs ranging from40 to 120 g/dL include.

Dizziness Depression/mood changes,

headache Fatigue Forgetfulness

Diminished reaction time

Lethargy Diminished visual motor performance

Malaise Impaired concentration


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Hematological Effects cont.:

Lead can induce two types of anemia Acute

high-level lead exposurehemolytic anemia

. chronic lead exposure , lead induces anemia byboth interfering with heme biosynthesis and by

diminishing red blood cell survival. The anemia

of lead intoxication is hypochromic, and normo-or microcytic with associated reticulocytosis.


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Endocrine Effects

Endocrine Effects Lead impedes vitamin D

conversion into 1,25-dihydroxyvitamin D,which is responsible for the maintenance of

extra- & intra-cellular calcium homeostasis

impaired cell growth, maturation,and tooth and bone development.


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Gastrointestinal Effects:

In severe cases of lead poisoning, children

or adults may present with severe cramping

abdominal pain, which may be mistaken foran acute abdomen or appendicitis.


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Reproductive Effects

Male Reproductive Effects Effects begin atBLLs of 40 g/dL

diminished sperm concentrations

total sperm counts, and total sperm motility. Pregnancy outcomes Increased frequency

of spontaneous abortions, miscarriages andstillbirths

. Lead crosses the placenta and can affectfetus viability as well as fetal development


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How to reduce exposure?

Carpool or drive the old car less

Get the soil around the older house to be

checked for lead content such as lead paintand lead pesticide level

Promoting recycling program

Checking old building for lead paints

R d ti f L d h d i


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Reduction of Lead hazards in

the home


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TREATMENT

Treatment for lead toxicity involves the use

of chelating agents, principally edetate

calcium disodium (CaEDTA),dimercaprol, penicillamine, and

succimer, which is given orally.


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interaction of lead

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