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Table of ContentsBuilding Materials and Health..........................................................................................................................1

ABBREVIATIONS...................................................................................................................................1FOREWORD..........................................................................................................................................2INTRODUCTION....................................................................................................................................3I. HEALTH HAZARDS ASSOCIATED WITH BUILDING MATERIALS...................................................4

A. Introduction..................................................................................................................................4B. Health and building materials: An overview.................................................................................4

C. Asbestos......................................................................................................................................6D. Metals........................................................................................................................................13E. Solvents.....................................................................................................................................15F. Formaldehyde............................................................................................................................19G. Insecticides and fungicides.......................................................................................................20H. Timber.......................................................................................................................................23I. Silica dust....................................................................................................................................23J. Earthen and traditional materials................................................................................................24K. Radon and its sources...............................................................................................................26L. Wastes.......................................................................................................................................30

II. CONTROLLING HEALTH HAZARDS: PROBLEMS AND ISSUES..................................................34III. A STRATEGY FOR THE CONTROL OF HEALTH HAZARDS ASSOCIATED WITH BUILDING

MATERIALS.................................................................................................. ......................................35A. Principles...................................................................................................................................36B. The role of the building industry.................................................................................................36C. The role of research and professional organizations.................................................................38D. The role of national governments..............................................................................................39E. International action....................................................................................................................41

ANNEX.................................................................................................................................................41REFERENCES.....................................................................................................................................43

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Building Materials and Health

UNITED NATIONS CENTRE FOR HUMAN SETTLEMENTS (Habitat)

The designations employed and the presentation of the material in this publication as well as the legal statusof any country, territory, city or area or its authorities, or concerning the delimitations of its frontiers orboundaries, do not imply the expression of any opinion whatsoever on the part of the Secretariat of the UnitedNations. The views expressed and the technical information and data given in this publication do notnecessarily reflect those of the United Nations. Mention of firm names and commercial products does notimply the endorsement of UNCHS (Habitat).

The manuscript of this publication was produced in 1995. It is printed in 1997.

HS/459/97EISBN9211313384

ABBREVIATIONS

General

CFC Chlorofluorocarbon

DDT Dichlorodiphenyltrichloroethane

EHC Environmental health criteria

ELF Extremely low frequency

HCH Hexachlorocyclohexane

LC50 Median lethal concentrationLD50 Median lethal dose

MMMF Manmade mineral fibre

OEL Occupational exposure limit

PCP Pentachlorophenol

POM Particulate organic matter

PVA Polyvinyl acetate

PVC Polyvinyl chloride

SVOC Semivolatile organic chemical

STEL Shortterm exposure limit

TBTO Tributyl tin oxideTLV Threshold limit value

TWA Time weighted average

UPVC Unplasticised polyvinyl chloride

UV Ultraviolet

VOC Volatile organic chemical

VVOC Very volatile organic chemical

Countries/Organizations

ACGIH American Conference of Government Industrial Hygienists

CIS Commonwealth of Independent States

DANIDA Danish International Development Agency

EPA Environmental Protection Agency

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EU European Union

FAO Food and Agriculture Organization of the United Nations

IARC International Agency for Research on Cancer

IFBWW International Federation of Building and Wood Workers

ILO International Labour Organization

IPCS International Programme on Chemical Safety

IRPTC International Register of Potentially Toxic Chemicals

ISO International Organization for StandardizationPAHO Pan American Health Organization

OECD Organization for Economic Cooperation and Development

UK United Kingdom of Great Britain and Northern Ireland

UNCHS United Nations Centre for Human Settlements (Habitat)

UNEP United Nations Environment Programme

IE/PAC Industry and Environment Programme Activity Centre

UNSCEAR United Nations Scientific Committee on the Effects of Atomic Radiation

USA United States of America

USSR Union of Soviet Socialist Republics (The former)

WHO World Health OrganizationUnits

bq bequerel

kg, g, mg, ?g Kilogram, gram, milligram,microgram

l litre

m, mm metre, millimetre

ppb parts per billion

ppm parts per million

pCi pico curies

s second

sv, msv, ?sv sievert, millisievert, microsievert

FOREWORD

The United Nations Commission on Human Settlements, in its decision 14/16 of 5 May 1993, requested theUnited Nations Centre for Human Settlements (Habitat) to explore the possibility of drafting an informativedocument on: (a) such building materials in the housing sector that are harmful or potentially harmful topeoples health and the environment, and (b) alternative building materials that could substitute for such

materials. In addressing adverse environmental effects produced by construction activities in general, andbuilding materials in particular, the Centre has conducted research study and published a document entitled:Development of National Technological Capacity for EnvironmentallySound Construction, (HS/293/93E).This publication identifies ways in which construction activities contribute to different areas of environmentalstress and proposes measures for reducing adverse environmental impacts through adoption andenforcement of effective strategies and regulations, application of improved technologies and through designand modified practices in construction.

In the past decade or so there has been increasing concern among scientists and professionals about thesuitability of certain building materials to environment and human health. The health hazards associated withbuilding materials has been subject of discussion in many fora and the time has come to look into the matterclosely. Given the importance of health as one of the most pressing areas of social concern, and in view of thevariety of health hazards which need to be addressed, a range of studies have already been conducted by

leading experts and agencies which discuss mainly the health hazards related to selected building materials.

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This publication covers a comprehensive research study conducted by UNCHS (Habitat) which focusesexclusively on ways in which a variety of building materials contribute to different aspects of health hazards,and the means available for prevention or mitigation of their adverse impact on health. The study outlines alsoan implementation strategy which could serve as a basis for controlling the health hazards associated withbuilding materials.

We gratefully acknowledge the contribution of Mr. Robin Spence, of the Cambridge Architectural ResearchLimited of the United Kingdom of Great Britain and Northern Ireland in preparing a draft background paper onwhich the present publication is largely based. We also gratefully acknowledge numerous scientists and

national/international agencies who provided comments and very useful inputs to the first draft of thisdocument. Finally, our thanks go to Mr. Kalyan Ray and Mr. Keso Msita of UNCHS (Habitat) who initiated theresearch design and to Mr. Baris DerPetrossian also of UNCHS (Habitat) who finalised the document.

It is hoped that this publication win be of interest to its readers and that it will complement other studiesproduced so far.

Darshan JohalAssistant SecretaryGeneral

Acting Executive DirectorUNCHS (Habitat)

INTRODUCTION

Risks to health usually result from exposure to harmful environmental conditions in the extraction, productionand use of building materials, and the disposal of related wastes. The harmful conditions include exposure todust, fumes, gases and vapours and toxic metals. The interaction of these factors and human organismsoccurs either by absorption through the skin, by intake into the digestive track via the mouth, or by inhalationinto the lungs. The results of the interaction can be harmful to human health in a variety of ways, including:respiratory diseases such as asthma, heart diseases, cancer, brain damage or poisoning. The effects of thehazards may be slow, cumulative, irreversible, and complicated by nonoccupational factors such assmoking.

The quality of the built environment too affects its; inhabitants in many ways and is dependent not only on thearchitectural form and specification, but also on the quality and nature of materials used, the care taken inconstruction, the quality of building services, design and components, and the timely and effectivemaintenance of the building fabric and support systems. The risks of diseases are also increased when thedwellings barriers against insect and rodent vectors are inadequate or poorly maintained.

Some of the health hazards associated with building materials and the builtenvironment are welldocumented and programmes to reduce them are in place. Others are and will be the subject of current andfuture research, therefore remedial measures are not yet in place. Furthermore the indications, based on

present knowledge, that a certain material is harmless to human health does not preclude possiblediscoveries of health hazards in future, bearing in mind the continuing advances in science and medicine.

The scope of this document is limited mainly to those hazards which are associated with the production anduse of building materials, and to some extent the disposal of wastes. The document is divided into threesections: Section I, discusses the nature of health hazards associated with the production of building materialsand their use and the demolition and disposal effects of some of the harmful materials and wastes; Section II,addresses the problems and constraints to the control of the harmful effects of building materials; and SectionIII, outlines a strategy for the control of health hazards focusing on the possible actions by the principal actorsinvolved with the production and use of building materials. Prior to finalising the document, the first draft wassent to more than thirty leading agencies, professionals and experts in the field for their comments which havebeen incorporated into this document.

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I. HEALTH HAZARDS ASSOCIATED WITH BUILDING MATERIALS

A. Introduction

This section briefly reviews the major health hazards associated with building materials according to threeprincipal stages of the construction cycle, namely: the production of building materials, construction andmaintenance, and occupancy. Furthermore, the section appraises the health hazards associated with fivegroups of potentially harmful and commonly Used materials, namely: asbestos, metals, solvents, insecticidesand fungicides and earthen materials. Radon emission and its effect on health has been discussed as manyof the building materials contain radium and so exhale radon which is a health hazard. An overview on thehealth impacts of wastes resulting from building materials has also been made. Finally, Table 19 provides asummary of building materials, their areas of application, related health hazards, substitute materials andmitigation strategies.

B. Health and building materials: An overview

Production of building materials

The materials delivered or supplied to site derive from a range of enterprises, operating at different scales,levels of technology and types of operation. Each type of material and production technology has its owncharacteristic health hazards. Many building materials industries derive their raw materials from quarrying ormining of minerals, in which workers are exposed to risks from blasting and rockfalls, and to dusts which cangive rise to a variety of lung and respiratory disorders.

The risks to asbestos workers were among the first identified hazards of building materials (Section I.C). Finedusts are also a problem in many other materialproduction industries, especially lime, cement and gypsummanufacture (1). Dusts of organic origin can likewise create health hazards of tumours and various allergicconditions for workers in sawmills and woodbased industries (1, 2).

Timber treatment often takes place offsite, using a variety of toxic chemicals, insecticides and fungicides, ina concentrated form which can be exceptionally hazardous to the health of workers exposed to them, and tothe health of neighbouring populations if care is not taken in the disposal of wastes (2).

Handling of the solvents used in the manufacture of paints and varnishes creates health hazards for theworkers in those industries (Section F). Workers in building materials production plants are also exposed to arange of industrial accidents from high temperature kiln processes (in cement, lime, brick production), rotatingmachinery, chemical spills and toxic effluent releases, and smokeladen atmospheres; and to hearing lossfrom intense noise (1).

Two factors mitigate the hazards to workers in material production plants. First, such plants are generallypermanent registered factories, where health hazards to workers can be monitored and controlled by propermanagement, and are subject to health and safety regulations, and are liable for inspection. Secondly,

although exposures are often concentrated, workers are exposed to the health hazards only during workinghours. However it should be cautioned that in many developing countries, the bulk of the smallscaleproduction of building materials takes place in the informal sector using rudimentally and inefficient technologyand ignoring legislation (3). Thus these mitigation measures do not have much relevance to the operation ofthe informal sector producers.

Construction and maintenance

The principal materialsrelated health hazards associated with the construction phase are dust, fumes,solvents and gases, and insecticides and fungicides. Many of the risks are most acute during this phase,where workers are exposed to health hazards in a concentrated form, but often without the workplace controlsof materials production. Some of the health hazards to which construction workers are particularly prone are

lung diseases from inhalation of dusts (particularly mineral fibres); skin and eye irritation and allergies fromvolatile organic chemicals released from paints and varnishes; and poisoning from the use of insecticides. Theworkers most at risk are those involved in the application of finishes (e.g. painters, decorators, and flooringcontractors); and in maintenance and renovation works, where the exposures are concentrated and often in

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confined indoor spaces. Maintenance work can also put building occupants at risk if the building continues tobe inhabited. A special hazard arises from the removal of asbestosbased materials during maintenance, as itcan introduce concentrations of fibres into the indoor atmosphere dangerous both to occupants and toworkers. Removal of toxic metalsbased paints also puts the inhabitants at risk. In both construction andmaintenance, disposal of toxic or harmful wastes can create hazards to workers, occupants and to the generalpublic.

Occupancy

The causal agents of ill health found in the indoor environment which are associated with building materialsinclude dusts and particulate matter, inorganic and organic chemicals, microbes, and arthropods. Table 1shows the range of such agents. The indoor environment typically contains numerous chemicals in the form ofdusts or gases, only some of which are attributable to building materials. Some building materials contributeby emitted chemicals of which they are made, or by contributing to the dusts as materials disintegrate.Materials can also act as a sink, storing chemicals from the surrounding atmosphere, and later releasing them(4). Such releases can be absorbed by the human body through inhalation.

A further range of organic chemicals is rapidly entering the indoor environment as a result of new products forthe treatment of materials and furnishings. These include formaldehyde, a group of volatile organiccompounds used, for example, in plastics and other polymeric materials; and pesticides which aresemivolatile and thus can remain in the environment for a long time, becoming adsorbed in dust or soft

furnishings and released later. All of these chemicals are also inhaled.

The inhalation of dust and gases can trigger a variety of responses. The possible health effects can beclassified as toxic, irritant or sensitising (5). Toxic effects may be acute, resulting in direct damage to organs,or chronic, causing for instance cancer, genetic damage or birth defects. Irritant effects are those which affectthe skin, or through inhalation, can cause discomfort or damage to the mucous membranes, the nose, lungsor eyes. Allergic effects include a variety of sensitivities, for example asthma, rhinitis or eczema.

Table 1. Causal agents of disease encountered in buildings.

Type Agents Subcategory Example

Chemical Inorganic Gaseous NO2, CO, SO2, O3, Chlorine

Particulate Dust (lead, copper, wood), mineral fibresOrganic Toxic Formaldehyde, solvents (toluene, styrene), pesticides (lindane,

Tributyl tin oxide)

Carcinogenic Nickel compounds, primers (lead), chromates, vinyl chloride,pesticides (arsenic, creosote)

Biological Microbes Viruses Influenza, colds,

Bacteria Legionella pneumophila, Plague

Fungi, moulds Spores, toxins,Mycotoxins

Plants Seed plants Pollen

Arthropods Mites Housedust mite faecal

Pellets

Vectors Protozoa Parasites: malaria,Chagas disease

Other Insects Flies, bugs, Cockroaches

Others Rodents Pets Rats, mice Skin scale, fur, feathersDroppings

Physical Sensible Temperature Hypothermia, heat, stress

Humidity Dry mucous membranes

Light Circadian

Sound Dissynchronisation, glare

Noise pollutionInsensible Electromagnetism

ionisingRadon

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Source: Crowther, D. (1994). Buildings and Health, Ph.D. Thesis, University of Cambridge,UK.

Microbes tend to thrive in the indoor environment. Damp, porous building materials can contribute to theconditions needed to enable these organisms to flourish. Arthropods inhabit buildings. In tropical regionssome of these are carriers of debilitating diseases such as malaria and dengue which are carried bymosquitoes, and Chagas disease which is carried by triatomine bugs. When dead, their disintegrated remainsand excreta collect in house dust, where they can cause a variety of allergic sensitivities. In northern climates,the most important arthropod is the housedust mite whose faecal pellets are held responsible for a

significant rise in asthmatic conditions (4). Other arthropods tend to inhabit small cracks and crevices inbuildings; thus they are encouraged by the use of building materials which are liable to crack, such asunstabilised earth, or thatched roofs.

Another aspect of building materials which can impact upon human health is their radioactivity, leading to theproduction of radon gas. Although in most instances their contribution to indoor radioactivity is smallcompared with soil radon gas, building materials produced from industrial waste products can have significantemissions. Radioactivity has a variety of carcinogenic effects.

In controlling health hazards, in residential or office buildings WHO recommends:

To ban excessively hazardous materials

To substitute less hazardous alternative products when available

To introduce sanitary clearance of new building materials and of consumer products asproposed in the European Union

To decrease human exposure through extensive natural ventilation of buildings

To use all possible ways of physical control of insects and rodents prior to the use ofpesticides

To keep all residential and office buildings very clean

C. Asbestos

Sources and health implications

The term asbestos covers a number of naturallyoccurring fibrous silicate materials in rock formations widelydistributed in the earths crust. However, only a few of the deposits are commercially exploitable. The principalvarieties of asbestos used commercially are chrysotile (hydrous magnesium silicate), a serpentine mineral,and crocidolite (iron and sodium silicate) and amosite (iron and magnesium silicate), both of which areamphiboles. Anthophyllite, tremolite, and actinolite asbestos are also amphiboles, but they are rare, and thecommercial exploitation of Anthophyllite asbestos has been discontinued (6).

While the properties of asbestos have been known for thousands of years, it is only in the last century, thatthe manufacture of building materials incorporating asbestos has been carried out on an industrial scale (7).The main use of asbestos fibres is in the manufacture of asbestos cement products. The products are basedon the addition of asbestos fibres (around 1015 per cent by weight) to a noncombustible filler such asPortland cement. Asbestos cement is a highcompression, highdensity, hardsurfaced material which iscommonly employed for fire protection panels, corrugated panels for roofing and cladding, roof tiles, firesurrounds, rain water goods, water tanks and water pipework etc. (8). The second largest use of asbestosfibres in the United States of America is the asphalt and vinyl floor tile manufacturing industry. Increased useof these types of tiles in many countries is due to their durability and impermeability to water (9).

Table 2. Principal varieties of asbestos, their theoretical formulae, world output (1984) and common uses in

building materials.

Mineral Theoretical formula Output tonnes Building materials

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Chrysotile (Whiteasbestos)

Mg3(Si2O5)(OH) 4,058,000 (96.6 percent)

Lightweight insulation and lagging,filler in plastics and roofing felts

Crocidolite (Blueasbestos)

Na2Fe(II)3Fe(III)2(Si8O22)(OH)289,000 (2.1 per cent) Sprayed steel coatings, pipe seals,additive to cement and boardproducts

Amosite (Brownasbestos)

(Fe,Mg)7(Si8O22)(OH)2 30,000 (0.79 percent)

Insulation board, ceiling tiles,asbestos cements and laggings

Anthrophyllite (Mg,Fe(II))7(Si8O22)(OH)2 20,000 (0.48 per

cent)

Lagging

Tremolite Ca2Mg5(Si8O22)(OH)2 High temperature applications

Actinolite Ca2(Mg,Fe(ll)5(Si8O22)(OH)2 With other types

Source: Spence, R. J. S., Cambridge Architectural Research Limited (UK), Building Materialsand Health (Unpublished draft report prepared for the United Nations Centre for HumanSettlements (Habitat), September 1994).

Note:The world production of asbestos has significantly changed since 1984. It was 4.3million metric tons in 1988, 4.0 million tons in 1990, 3.5 million tons in 1991, and 3.1 milliontons in 1992 (United States Department of Interior, 1993: Asbestos in 1992. Mineral IndustrySurveys; United States Bureau of Mines, 1993). Out of the 3.1 million tons in 1992 more than

95 per cent was chrysotile. Amphibole production has declined sharply, with South Africanproduction of crocidolite and amosite dropping from 280000 tons in the late 1970s to 55000tons in 1992 (Industrial Minerals, 1992: Asbestos Production: The Chrysotile Crysis?). Thelast amosite mine, which operated in South Africa, closed in 1992. The total United Statesconsumption of asbestos in 1991 was 34000 metric tons, and in 1992 only 33000 metric tons.Only 500 metric tons of crocidolite was consumed in 1992 and no amosite (United StatesFederal Register, vol.59, No. 153. Occupational Exposure to Asbestos; Final Rule, p.41027).

Epidemiological studies, mainly on occupational (mining and milling, manufacturing, or product application)groups, have established that all types of asbestos fibres may be associated with asbestosis, bronchialcarcinoma, and mesothelioma (9). A brief account of these health problems is as follows (7, 10, 11):

Asbestosis. This is a deposition of fibrous tissues in the lung parenchyma the regionwhere oxygen exchange takes place. Initial coughing is followed by progressive difficulty inbreathing. The patient may eventually die of cardiorespiratory failure. Severity of the diseaseis related to cumulative exposure to asbestos (a dose relationship), although it may bearrested in the early stages if contact with asbestos ceases. Asbestosis has a long latentperiod, rarely being seen less than 10 years after first exposure to asbestos. It seems thatthere is a threshold level below which the condition does not occur;

Bronchial carcinoma (lung cancer). As with, asbestosis, there is a dose relationship but itis uncertain whether there is a threshold level below which there is no risk. There appears tobe a multiplicative effect on smokers: the risk to asbestos workers who smoke is ten times asgreat as to nonsmokers;

Mesothelioma. A malignant tumour on the lining of the chest cavity (pleural mesothelioma)or abdomen (peritoneal mesothelioma). The latent period for the disease is very long anaverage of more than 30 years from first exposure. Mesotheliomas have a very poorprognosis, being unresponsive to most cancer therapies; and

Nonmalignant conditions such as diffuse thickening or effusion (fluid in the lungs). Theselung abnormalities may cause breathlessness but are often asymptotic.

Already in 1987, a WHO publication (37), the Air quality guidelines for Europe, described, inter alia, thecarcinogenic effect of asbestos. In addition, the European Community has issued several directives in whichthe marketing and use of dangerous substances are regulated, e.g. Council Directive 76/769, and the fifth andseventh amendments to this directive provide for restrictions on the marketing and use of asbestos. Germany

has incorporated the provisions of these directives in its national legislation. Except for some negligibleexemptions, asbestos is prohibited in Germany.

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Health risks due to exposure to different asbestos types are dependent on the fibrous structure of thematerial, thus asbestos types which are liable to form fibres less than 3 microns in diameter, principally theamphiboles, are most hazardous (10). The fibre length is also important, with fibres longer than approximately8 microns posing greatest risk. The principal risk is through inhalation of airborne fibres, since there is littlechance that fibres will penetrate the skin or be absorbed from the digestive tract.

Past exposure to asbestos in industry or in the general population has not been sufficiently well documentedto make an accurate assessment of the risks from future levels of exposure, which are likely to be low (6).There are two possible approaches for assessment of risks, one based on a comparative and qualitative

evaluation of the literature (qualitative assessment), the other on an underlying mathematical model to linkfibre exposure to the incidence of cancer (quantitative assessment). Attempts to derive the mathematicalmodel have had limited success (6). However, on the basis of qualitative assessment, the followingconclusions have been drawn (9):

Among occupational groups, exposure to asbestos poses a health hazard that may result inasbestosis, lung cancer, and mesothelioma. The incidence of these diseases is related tofibre type, fibre dose, and industrial processing;

In paraoccupational (neighbourhood of an asbestos industrial plant, or home of anasbestos worker) groups, the risk of mesothelioma and lung cancer is generally much lowerthan for the occupational groups. Risk estimation is not possible because of the lack of

exposure data required for doseresponse characterization. The risk of asbestosis is verylow;

In the general population, the risks of mesothelioma and lung cancer attributable toasbestos cannot be quantified reliably and are probably undetectable by epidemiologicalmethod. The risk of asbestosis is virtually zero;

On the basis of available data, it is not possible to assess the risks associated with exposureto the majority of other natural mineral fibres in the occupational or general environment. Theonly exception is erionite, for which a high incidence of mesothelioma in a local populationhas been associated with exposure. Such exposure to erionite is exceptional, andexposurerelated mesothelioma were described in only one country, being probably theconsequence of outdoor exposures since birth (51).

The health hazards associated with use of asbestos in the construction industry have come to a sharper focusin recent years: there has been a growing alarm about risks to dangers of breathing fine asbestos. On theother hand, there are others who believe that not enough toxicological and medical data are available to justifya ban on asbestos and asbestos products and that a lot more research is necessary before a judgment couldbe arrived at, and that the existence of asbestos related diseases reflects neglect of working conditions in thefactories and ignorance regarding the science of occupational diseases associated with asbestos in the past(12). However, due to the undisputed fact that asbestos is one of the identified carcinogens, in many countriesthe manufacture and use of asbestosbased products have been strictly controlled in recent years. Forexample:

Use of crocidolite and amosite types of asbestos is increasingly being discontinued (they are

banned in the European Union countries and Japan);

The number of uses and the total consumption of asbestos and its products in theNetherlands have fallen sharply in recent years (13);

The demand for asbestos was less than onethird in United States of America, in 1987compared to its peak in 1973 (14). The demand was 672000 metric tons in 1977, and 34000metric tons in 1991 (Pigg BJ: The uses of chrysotile. Ann Occup Hyg, 1994; 38: 453458).

Furthermore, ILO convention 162, requires governments to prohibit the use of crocidoliteand spraying of all forms of asbestos (15), and has issued a series of publications namely:The ILO Code of Practice on Safety in the use of Asbestos, 1990; the ILO Occupational

Safety and Health Series No. 30 and No. 64; Asbestos: Health Risks and their Prevention,1974; Safety in the Use of Mineral and Synthetic Fibres, 1990 and the ILO Conventionconcerning Safety in the Use of Asbestos, 1986 (No. 162) and its accompanyingRecommendation, 1986 (No. 172).

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Recently the So Paulo Declaration, an outcome of the Asbestos International Seminar: Controlled Use orBan, held in Sao Paulo Brazil in March 1994, demanded the prohibition of all uses of asbestos and thepromotion of substitutes which are less dangerous to the health and safety of workers (16).

The United States EPA in 1989 issued a Rule to prohibit the future manufacture, importation, processing, anddistribution of all types of asbestos in almost all products, however the rule was overturned by a United StatesCourt of Appeals in 1991. As a result, most asbestos products are not subject to the Ban and Phase out Rule(Prof. F. Valic, IPCS Consultant and Chen, B. H., WHO).

In spite of the opposing views about asbestos, the controlled use of asbestos appears to be favoured byagencies such as ISO, ILO, the United Nations Economic Commission for Europe, OECD, and theCommission of European Union (EU) (12). However, substitution of asbestos should be considered when safecontrol cannot be assured. While waiting for the time when it will be economically feasible to ban asbestosuse all around the world, WHO recommends: Workers in asbestos industries must wear protective respiratoryequipment and never smoke any tobacco; there is no risk from using water pipes in asbestoscement; andthe risks from asbestoscement roofs are kept properly lined and maintained in such a way as to prevent fibreemissions.

Factors influencing exposure

Risk groups which may be exposed to high asbestos levels are: workers in asbestos manufacturing and

processing industries, and maintenance and demolition workers (13). Risks to construction and maintenanceworkers and building occupants occur when the material containing asbestos is subjected to roughmechanical treatment releasing respirable fibres into the air. Installed components, for example sheetmaterials which may be sealed by a layer of paint, pose little risk unless degradation occurs by physicalabrasion. Chemical attack is a possibility in the case of asbestos cement products in contact with water(especially if aggressive due to pH rating and ion content), for example roof sheets and downpipes (17).

The most serious risks to construction workers are likely to be associated with demolition, or programmes ofremoval aimed at eliminating asbestos products from a building. There are often problems in identifyingcomponents which contain asbestos, particularly since many are virtually indistinguishable from the substitutematerials which have been developed incorporating manmade mineral fibres. Sampling and analysis byexperts in the field may be necessary for correct identification.

Since stripping of asbestoscontaining materials often raises exposure levels for building occupants as wellas the contractors for a considerable period of time, the risks involved in such actions must be carefullybalanced against predicted risks if the materials remain in place. Insitu repair work and sealing may bepreferable to fullscale removal, particularly if the asbestos is in a relatively inaccessible location. Heavyphysical exertion increases the respiration rate and thereby the exposure dose. Smokers too constitute a riskgroup with an increased susceptibility to lung cancer.

Acceptable exposure levels

Most developed countries have regulated their asbestos industries, with specified limits to asbestos exposure.In the United Kingdom of Great Britain and Northern Ireland (UK) for example, control limits and action levelsare set out by the Control of Asbestos at Work Regulations 1987 (amended 1993). At exposures above the

control limit, respirators fitted with the correct filter must be worn. In applying the exposure limit, fibre isdefined as a particle with length more than 5 microns, diameter less than 3 microns and ratio of length todiameter greater than 3:1. For chrysotile alone, the control limit is 0.5 fibres per millilitre (f/ml) of air averagedover 4 hours, or 1.5 f/ml averaged over any 10 minute period. For any other type of asbestos, whether or notmixed with chrysotile, the corresponding limits are 0.2 and 0.6 f/ml. If workers exposure exceeds the actionlevel, the employer is obliged to arrange medical examinations at a maximum of 2 year intervals and to keepaccessible medical records for at least 40 years.

In the case of the United States of America, the United States Environmental Protection Agency (EPA), in1988 took new regulatory action on additional protections to state and local government employees coveredby the EPA asbestos abatement worker protection (6). EPA defines fibre as a particulate form of asbestos 5micrometres or longer, with a lengthtodiameter ratio of at least 3 to 1. The Permissible Exposure limit to

workers exposed to airborne asbestos being 0.2f/cc of air, averaged over an 8hour day. The action level is0.1f/cc averaged over 8 hours. The action level is the level at which employers must begin activities such asair monitoring, employee training, and medical surveillance. WHO recommends that, inside buildings theconcentration of asbestos fibbers must stay below 500 fibbers per cubic meter. In the case of environmental

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exposure, it has been estimated that fibre concentrations are unlikely to exceed one thousandth of the controllevel (18). A typical situation might give a lifetime excess risk of death from mesothelioma of 1 or 2 in 10,000(18). For lung cancer, the same source predicts an excess mortality of two per million. As noted above, thereappears to be a threshold effect for asbestosis which limits its impact to workers in the asbestos industry, withlittle if any effect on those subject to nonoccupational exposure. However, the United States OSHA hasrecently issued a new Rule on Occupational Exposure to Asbestos (United States OSHA, Department ofLabour: Occupational Exposure to Asbestos. Federal Register 1994, Vol. 59, No. 153, 4096441158) forgeneral industry, construction and shipyard industry specifying permissible exposure limit of 0.1 fibre/cm3 ofair as an 8hour timeweighted average, and an excursion limit of 1.0 fibre/cm3 of air as averaged over a

sampling period of 30 minutes. Special attention is given to exposure of workers during repair andmaintenance of automotive brakes and clutches, and to exposure of custodian staff.

Mitigation strategies

Construction activities (including renovation, demolition and insulation) should be designed and planned toeliminate or reduce the need for mineralfibre based materials which have a cancer producing potential.Stringent handling regulations in the manufacture, use, transportation, demolition, storage and disposal ofasbestos must be established. These could potentially be extended to MMMFs if continued monitoring of theireffect shows that to be necessary. In view of the reported carcinogenic properties of asbestos after inhalation,exposure via the respiratory route should be avoided as far as possible. To avoid eye and skin irritations,protective clothing and spectacles should be used. Employers should develop a training programme for all

employees who are exposed to airborne concentrations of asbestos at or above the action level. The trainingprogramme must inform employees about the methods of recognizing asbestos and the health hazards ofasbestos exposure; the relationship between asbestos and smoking in producing lung cancer; operationswhich could result in asbestos exposure; the importance of necessary protective controls to minimizeexposure including, as applicable: engineering controls, work practices, respirators, housekeepingprocedures, hygiene facilities, protective clothing, decontamination procedures, emergency procedures andwaste disposal procedures; the purpose, proper use, and limitations of respirators; and the medicalsurveillance programme (6). Furthermore for construction workers who may be exposed to asbestos dust,hazards will be mitigated further by following advice issued to workers in the asbestos industry:

be aware of the materials likely to contain asbestos, and potential risks;

follow recommended working procedures, for example using hand tools for cutting anddrilling asbestos products rather than mechanical tools;

keep the working area clean; damp down dust before removal by vacuuming withspeciallydesigned equipment; do not blow away debris with an airline;

ensure waste material is properly collected in marked dustproof containers for safe disposal;

wear protective clothing and a respirator where appropriate;

wash or shower at the end of the working day;

do not take working clothes home; and

avoid smoking.

Employers have a duty to protect the workforce by taking all possible steps to minimize health risks. Theyshould ensure that workers follow the guidelines above; they should provide suitable equipment and facilities(e.g. for showering), monitor exposure and when necessary arrange medical checks. Measures of this typehave been adopted by the Indian government through the publication of 16 Indian Standards on Safety in theUse of Asbestos. In addition, the Indian government has established a Development Panel and the AsbestosProducts Industry and an Expert Group to examine the feasibility of substituting alternative products (12).

Substitute materials

The substitution of asbestos should be considered where safe control cannot be achieved. Many materialshave been developed as substitutes for asbestos based products, a large proportion of which use

Manmademineral fibres (MMMFs). MMMFs, known as mineral wools or other types of fibres, (a term usedis the United States of America to refer to mixtures of rock and slag wools) are amorphous glassy fibres made

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from molten slags, natural rocks such as basalt and borosilicate or calcium silicate glasses; chemically theyare all amorphous silicates. Their use has increased greatly since the 1960s, partly due to a growingawareness of risks associated with asbestos. Applications of MMMFs are: reinforcement to glass reinforcedcement; glass reinforced plastic and rubber; textiles and electrical insulation; insulating quilts, bats andboards; tiles, pipes and ductwork; acoustic insulation; high temperature thermal insulation e.g. lining refractorykilns; joints and gaskets; and as high efficiency air filters.

Studies however indicate that all respirable size MMMFs are not biologically inert and health hazards posedby them require thorough investigation. The International Agency for Research on Cancer (IARC) has

indicated that (19):

There is sufficient evidence for the carcinogenicity of glasswool and of ceramic fibres inexperimental animals;

There is limited evidence for the carcinogenicity of rockwool in experimental animals;

There is inadequate evidence for the carcinogenicity of glass filaments and of slagwool inexperimental animals;

There is inadequate evidence for the carcinogenicity of glasswool and of glass filaments inhumans;

There is limited evidence for the carcinogenicity of rock/slagwool in humans;

No data were available on the carcinogenicity of ceramic fibres to humans.

Thus IARC (20), in accordance with its carcinogenic evaluation criteria (table 3), has concluded in an overallevaluation of the effects of glasswool, rockwool, slagwool and ceramic fibres that they are possiblycarcinogenic to humans. On the other hand glass filaments are not classifiable as to their carcinogenicity. Itshould be noted that for carcinogens, in WHO guidelines, the values are based on an accepted risk of oneadditional cancer per year per hundred thousand exposed people. In countries where most deaths occurredfrom infections diseases, WHO considers it appropriate to compute safety standards on the basis of anaccepted risk of one additional cancer per year per ten thousand exposed persons.

Table 3. IARC Carcinogenic evaluation criteria.

Group Description

1 The agent (mixture) iscarcinogenic to humans.The exposure circumstanceentails exposures that arecarcinogenic to humans

Used only when there is sufficient evidence of carcinogenicity in humans.Exceptionally, an agent (mixture) may be placed in this category when evidencein humans is less than sufficient but there is sufficient evidence ofcarcinogenicity in experimental animals and strong evidence in exposedhumans that the agent (mixture) acts through a relevant mechanism ofcarcinogenicity.

2A The agent (mixture) isprobably carcinogenic to

human. The exposurecircumstance entailsexposures that are probablycarcinogenic to humans

Used when there is limited evidence of carcinogenicity in humans and sufficientevidence of carcinogenicity in experimental animals. In some cases, an agent

(mixture) may be classified in this category when there is inadequate evidenceof carcinogenicity in humans and sufficient evidence of carcinogenicity inexperimental animals and strong evidence that the carcinogenesis is mediatedby a mechanism that also operates in humans. Exceptionally, an agent, mixtureor exposure circumstance may be classified in this category solely on the basisof limited evidence of carcinogenicity in humans.

2B The agent (mixture) ispossibly carcinogenic tohumans. The exposurecircumstance entailsexposures that are possiblycarcinogenic to humans

This category is used for agents, mixtures and exposure circumstances forwhich there is limited evidence of carcinogenicity in humans and less thansufficient evidence of carcinogenicity in experimental animals. It may also beused when there is inadequate evidence of carcinogenicity in humans but thereis sufficient evidence of carcinogenicity in experimental animals. In someinstances, an agent, mixture or exposure circumstance for which there isinadequate evidence of carcinogenicity in humans but limited evidence ofcarcinogenicity in experimental animals together with supporting evidence fromother relevant data may be placed in this group.

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3 The agent (mixture orexposure circumstance) isnot classifiable as to itscarcinogenicity to humans.

This category is used most commonly for agents, mixtures and exposurecircumstances for which the evidence of carcinogenicity is inadequate inhumans and inadequate or limited in experimental animals. Exceptionally,agents (mixtures) for which the evidence of carcinogenicity is inadequate inhumans but sufficient in experimental animals may be placed in this categorywhen there is strong evidence that the mechanism of carcinogenicity inexperimental animals does not operate in humans.

Agents, mixtures and exposure circumstances that do not fall into any other

group are also placed in this category.

4 The agent (mixture) isprobably not carcinogenic tohumans.

Used for agents for which there is evidence suggesting lack of carcinogenicityin humans together with evidence suggesting lack of carcinogenicity inexperimental animals. In some circumstances, agents for which there isinadequate evidence of carcinogenicity in humans but evidence suggesting lackof carcinogenicity in experimental animals, consistently and strongly supportedby a broad range of other relevant data, may be classified in this group.

Source: IARC (1994). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans.Preamble, International Agency for Research on Cancer (IARC), Lyon, France.

Other related health hazards include skin, eye and upper respiratorytract irritations such as bronchitis (21).

Occupational health hazards are due to improper exposure to MMMFs. According to IFBWW (21), mostcountries in the world treat MMMFs as nuisance dust and in most cases follow a standard of 10 mg/m3 of totaldust or 5 mg/m3 for respirable dust. Examples of introduced more stringent fibre and gravimetric standards forMMMFs are as follows (21, 22):

In Denmark, stationary workplaces must meet a 2. Of/ml fibre standard, and innonstationary workplaces a 5 mg/m3 total dust standard is in effect;

In Sweden, all work involving synthetic or inorganic fibres must meet a 1.0f/ml standard;

In the United Kingdom of Great Britain and Northern Ireland a fibre standard of If/ml applies,as well as a total inhalable dust limit of 5 mg/m3;

In Australia all work with MMMFs must meet a 0.5f/ml standard as well as a 2 mg/m3

respirable dust standard;

In Germany there is no more TLV because MMMFs with diameter less than 1 ?m arejustifiably suspected of having carcinogenic potential; and

In Canada, Alberta has adopted a limit of 1.0f/ml for fibrous glass and mineral wool and0.5f/ml limit for refractory ceramic fibres, and a total dust standard of 5 mg/m3 for work withthese materials also applies.

Other alternatives which do not contain mineral fibre such as metallic or ceramic products are often lessavailable or considerably more expensive. The possible hazards posed by fibrous materials may have to beconsidered in relation to these other disadvantages in selecting components. For new buildings, nonfibrousalternatives to asbestos should be considered first. Whenever MMMFs substitutes are considered, and as inthe case of asbestos, appropriate work practices, engineering, and administrative control measures shouldaim at controlling the exposure of workers to airborne dust and fibres. Substitute materials and nonfibrousalternatives are suggested in table 4.

Table 4. Examples of asbestosbased materials, MMMFbased substitutes and alternatives

Asbestosbased material MMMFsbased substitutes Alternatives

asbestos based thermalinsulation

glass fibre or rockwool quilt,rockwool bats

cellulose quilt, expanded or extrudedpolystyrene board polystyrene beads

asbestos pipe lagging mineralwool lagging or preformedsections foamed rubber or polystyrenesections

asbestos cement or asbestos mineral fibre filled double walled masonry chimney, preformed

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filled double walled metallicflues

metallic flues concrete block flue, double walledmetallic air filled flue

asbestos based acousticinsulation

mineral fibre reinforced sprayedplaster

foamed rubber or polystyrene,textiles, textured plaster

fireproof lining sheets glassreinforced cement board,calcium silicate based board

multilayer plasterboard

sprayed asbestos fire proofing intumescent coating

asbestos cement roofing sheets fibre reinforced calcium silicate

sheets, glass reinforced cement, glassreinforced plastic

vegetablefibre cement sheets,

profiled steel, sheet metal (zinc,aluminium etc.)

asbestosbased roofing felt glass fibre based felt polyesterbased or pitch polymerfelts

asbestos cement slates glass reinforced cement natural slate, clay or concrete tiles,PVA cement slates

asbestos cement water storagetanks

glass reinforced cement polythene, polypropylene, galvanisedmild steel

asbestos cement rainwatergoods

glass reinforced plastic cast iron, aluminium, uPVC

asbestos cement eaves, soft

board

glass reinforced cement board,

calcium silicate board

softwood, plywood, PVA cement

boardasbestos fibre/vinyl floor tile orsheet

mineral fibre/vinyl tile or sheet thermoplastic tiles, linoleum, clay tiles


D. Metals


A number of metals are used in the construction industry in their metallic form, making use of their structuralproperties, their resistance to water penetration or their high thermal and electrical conductivity or ascompounds, primarily in paint and other finishes. Most of them are harmless in fact, dietary intake of manymetallic elements is essential to health. Risks may however result from excessive intake of certain metals.The two principal buildingrelated sources are: soluble metallic salts in water supply, from the use of metals inpipework and joints, storage tanks and roof flashings, gutters and downpipes; and paint flakes, which may beingested. The metals of potential concern are cadmium, chromium and lead.

Cadmium is highly toxic: exposure may result in bone damage, kidney damage and lung cancer. Again, theprincipal sources are dietary, but paints may also present risks. Cadmium may also be present as a

contaminant of foam rubber carpet backing.

Chromium is most toxic in the valence state chromium. It too is a component of some paints and metallicfinishes and may be a contaminant of cement. Mining waste may contaminate ground water. Health effectsobserved in chromiumindustry workers include: contact dermatitis on exposed skin; ulceration if the skin ispenetrated through cuts and abrasions; if inhaled, inflammation of the larynx and perforation of the nasalseptum; liver damage; lung cancer, and possible other types of malignant tumour.

Lead is perhaps the most important constructional metal with health implications. The workability of lead in itsmetallic form has made it an important material for roofing and associated works such as flashings, valleygutters and rainwater hoppers. It has also been used for water supply pipes. Other uses include glazing barsfor stained glass or smallpaned windows, as an additive in linseed oil putty, and as an important componentof traditionallyformulated paints, in particular in primers for external use on wood and metal: red lead and

calcium plumbate primers contain over 20 per cent lead in their liquid state. Even paints for internalapplication such as eggshell finishes may contain a considerable proportion of lead. The effects of leadpoisoning have been recognised for hundreds of years in lead miners and smelters. There are other health

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risks associated with lead, but these are of concern primarily in lead using industries such as battery andlead shot manufacture, and in the mining and smelting of lead, and are not of significance to the constructionand building materials industries (23).


Concentration of soluble lead salts in water supplied through lead pipework is dependent on thecharacteristics of the water. Soft, acidic waters show the greatest tendency to leach lead from plumbing, butproblems can also be encountered with some types of hard water. The water temperature and the length of

time that it has been in contact with lead plumbing are also important factors (17). Children are particularlyliable to be affected by potentially toxic metallic compounds in paintwork. Small children spend a large part oftheir time at floor level, where they are susceptible to paint and solder flakes in household dust. Furthermore,some children develop a condition known as pica, characterised by a craving to eat nonfood substances.Paint flakes can be a favourite meal.


In the case of chromium, the World Health Organisation (WHO) recommended upper limit in drinking water is0.05 parts per million (50 ?g/1). For lead, an upper limit of 50 microgrammes per litre for mains water hasbeen accepted by the European Union (EU) (17). However, many households supply from the tap may wellexceed this, because of leaching from plumbing installations. For example, a survey carried out in Scotland in

the mid70s showed that tap water in 21 per cent of households exceeded a level of 100 microgrammes oflead per litre. An upper limit in blood level concentration of lead of 35 microgrammes per 100 millilitres hasbeen set by the EU. The British government advises that environmental exposure to lead should be reduced ifan individuals blood level concentration exceeds 25 microgrammes per 100 millilitres, particularly in the caseof a child. Supported by scientific data from the United States of America (24) a number of Europeangovernments are considering lowering this level to 1015 ?g/dl. WHO has made an international riskevaluation on health effects from exposure to inorganic lead and the results will be published in EnvironmentalHealth Criteria No. 165 on Inorganic Lead in 1995 by WHO. The most substantial evidence fromcrosssectional and prospective studies of populations with BPb levels generally below 25 ?g/dl relates todecrements in intelligence quotient (IQ). It is important to note that such observational studies cannot providedefinitive evidence of a causal relationship with lead exposure. Existing epidemiological studies do not providedefinitive evidence of a threshold. Below the BPb range of 1015 ?g/dl, the effects of confounding variablesand limits in the precision of analytical and psychometric measurements increase the uncertainty attached toany estimate of effect. (WHO. 1995, Environmental Health Criteria No. 165, Inorganic Lead in press).However, while the medical effects of acute poisoning including stomach ache, constipation and vomiting are clear, there is less consensus about the effects of low level exposure. The threshold level is uncertain,and there is considerable scientific debate about appropriate action levels (23).


If roofs have lead finishes or components such as valley gutters, the use of runoff water for cooking anddrinking should be avoided. Leadbased paints, and other toxicmetal based paints too should never be usedin situations accessible to children, particularly on nursery furniture or play equipment. To minimise the risksof exposure to lead compounds, paintwork should be kept in good condition: recent, leadfree paint maycover older layers of traditional paints and primers containing lead or other potentially toxic metallic

compounds. It has been estimated that 60 per cent of the domestic stock in United States of America containsleaded paintwork, amounting to 3 million tons (24). Good maintenance of all paintwork may be preferable toremoval: renovation of older timber houses in United States of America has been shown to raise occupantsblood lead levels two times, thus a doubling of the average load (25). Where old paintwork possiblycontaining lead needs to be stripped to give a good surface for redecoration, it is advisable to use achemical stripper rather than mechanical methods (particularly those using exposed flame or hot air above500C). Good ventilation should be provided. Wet sanding is a possibility for large areas, provided that theresulting dust is carefully collected. All debris from stripping old paintwork should be meticulously clearedaway for disposal. Any paints containing lead, chromium or cadmium should be clearly labelled with theircontent of these metals as wet film and dried paint. Unsuitable uses should also be indicated particularly inlocations accessible to children.


WHO recommends an immediate ban of leaded paints and progressive elimination of lead as waterpipematerial. Substitute materials are suggested in table 5.

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Table 5. Constructional uses of potentially toxic metals, and alternatives

Use in building construction Alternative material

Lead sheet as roof finish Sheet aluminium, zinc or copper;plastic coated/profiled steel;elastomeric sheet; builtup felt roofing

Lead flashings and soakers Preformed PVC, glass reinforcedplastic, aluminium

Lead rainwater hoppers Cast iron, cast aluminium or PVCLead concealed or valley gutters Zinc, elastomeric sheet, preformed

PVC

Water supply pipes Copper, stainless steel, plastics

Leadalloy fittings to water supply pipes Copper, brass, plastics

Lead solder to water supply pipes Tin, silver solder; plastic or brasscompression fittings; solvent joints (forplastics)

Lead came to leaded lights in glazing Copper, lead strips on internal face ofglass within double glazing

Leaded glazing putty Unleaded linseed oil putty, synthetic

rubber or polysulphide based glazingcompounds, timber or metal glazingbeads

Any paints containing lead, chromium or cadmium, such as calciumplumbate primer, red lead primer, metallic lead primer, red oxideprimer, and zinc chromate metal primer

Vinylbased paints, polyurethanevarnishes and most waterbasedstains.


E. Solvents


Organic solvents are very widely used in construction as key ingredients of adhesives, paints, flooringmaterials and mastics. The most commonly used solvents include white spirit, toluene, xylene,trichloroethane, styrene and carbon tetrachloride. Paints, glues and lacquers contain toluene, methyl nbutylketone, nhexane and xylene. Paint strippers and solvents contain white spirit and dichloromethane andexpanded plastics contain styrene.

If inhaled, solvents dissolve readily in the blood stream. Sufficiently low concentrations will be metabolised

quickly with no ill effects by the body, but if exposure is excessive a variety of health effects can occur,including sedation effects ranging from slowed reaction time and decreased vigilance to anaesthesia, irritationto the eyes, nose and throat, liver damage, and damage to the nervous system (26).

The International Federation of Building and Wood Workers has reported major health hazards for painterswhich include (27):

Occupational cancer Painters run a high risk of getting cancer from the chemicals withwhich they work: benzene can cause leukaemia; carbon tetrachloride can cause liver cancer;all chlorinated solvents (those with Chloro or Chloride in their names) are suspectedcarcinogens, for example, methylene chloride is a suspect carcinogen because it causescancer in animals. See also table 6. A complete list of known cancer agents evaluated byIARC is given in the Annex. For the evaluation criteria refer to table 3.

Painters Syndrome is the name given to the effects on health which may arise fromlongterm exposure to organic solvents. Organic solvents get into the body and brain through

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the lungs or skin and slowly cause permanent changes in the brain and the central nervoussystem. Solvents may also damage the peripheral nervous system which is the system ofnerves leading from the spinal cord to the arms and legs. The symptoms caused by thisdamage are numbness and tingling in the hands and feet, weakness and paralysis.

Occupation skin diseases all solvents can dissolve the skins protective barrier of oils,causing dermatitis. There are two types of contact dermatitis: irritant contact dermatitis, andallergic contact dermatitis. Contact dermatitis is the most common occupational skin disease,caused when the skin comes into contact with certain chemicals which can make the skin red,

sore, inflamed, irritated, cracked, dry and itchy, and sometimes rashes and blisters maydevelop. Anyone working with paints and coatings runs a high risk of contracting irritantcontact dermatitis because many paints and coatings contain chemicals which irritate theskin. This is a nonallergic skin reaction from exposure to irritating substances. Exposure toirritants accounts for 80 per cent of the cases of occupational contact dermatitis.

Allergic contact dermatitis is a type of dermatitis caused by becoming allergic or sensitisedto particular chemicals called allergens. Common allergens include epoxy adhesives,chromium and nickel compounds. Once someone has developed an allergy to a chemical(has become sensitised), the dermatitis will flare up again, usually within twelve hours aftercontact with the chemical. Some workers develop allergic contact dermatitis after many yearsof trouble free working with paints/coatings. Other workers never develop it at all even though

they work with the same paint ingredient that gives allergic contact dermatitis to otherpainters. Allergic contact dermatitis is not easy to treat. Studies show that 25 per cent ofpeople with allergic contact dermatitis will not recover from their allergy and will have to leavetheir work so as to avoid all contact with the allergens.

Occupational lung diseases occupational asthma; lung irritation from paint vapours andmists, lung tumours in painters and chronic bronchitis/emphysema. Occupational asthma isthe result of becoming allergic to a chemical or substance. Once the lungs become allergic toa lung allergen, the symptoms of asthma can come back with exposure to a tiny amount ofthe substance. This means some workers are forced to leave their jobs because the asthmais so serious. It can be very difficult to lose an allergy. Common symptoms are wheezing,shortness of breath and coughing but there can also be other symptoms.

Table 6. A list of some of the known cancer agents related to painting as evaluated by IARC (27,28).

Cancer Agent IARC Group Likely Sources

Chromates 1 Primers, paints

Cadmium 1 Pigments

Benzene 1 Solvents, some thinners

Methylene Chloride 2B Paint strippers

Styrene 2B Organic solvent, e.g. in some polyesters, putties and fillers

Nickel Compounds 1 Pigments

3,3 Dichlorobenzidine 2B Pigments

Lead 2B Primers, dryers, some pigmentsAntimony oxide 2B Some pigments,

2Nitropropane 2A Organic solvent

Tetrachloroethylene 2B Organic solvent for degreasing

Source: IFBWW Series 3 (1992). Solvents and Paint Hazards, International Federation ofBuilding and Wood Workers, Geneva, and IARC (1995). IARC Monographs on the Evaluationof Carcinogenic Risks to Humans. Lists of IARC Evaluations, Lyon, France.


An important characteristic of the hazardous substances in forms of gases and vapours which stronglyinfluences their significance as health hazards is their volatility. Highly volatile substances are those with lowboiling points, which will give off gases and vapours at a very rapid rate at normal temperatures. A study onthe solvent vapour hazards during painting with white spirit borne eggshell paints, indicated that when

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painting was carried out at a lower temperature (12C instead of 24C) the rate of solvent vapour release,and consequently the hazard, was reduced by about 25 per cent (29). The same study concluded that the useof such paints in unventilated conditions can constitute significant health hazards: in the trials the shorttermexposure limit (STEL) for whitespirit vapour was exceeded approximately 10 minutes from the start ofpainting, and concentrations approaching 700 ppm for a 10 minute time weighted average (TWA) werereached before completion of painting. The allowable longterm exposure limit for an eight hour time weightedaverage (TWA) exposure is 100 parts per million (ppm), and the shortterm exposure limit (STEL) for anygiven 10minute period is 125 ppm (29). Thus, unless ventilation is good, hazardous concentrations caneasily be reached shortly after use or installation; but the rate of emission will decline rapidly, and they are not

likely to be a longterm problem, except where, for some reason, emissions are delayed. Substances of lowvolatility, or semivolatile substances, conversely, are not emitted rapidly: but they can continue to be emittedfor a long period of time; they can be absorbed by dust and furnishing materials, and then later be reemittedto the environment; and they are metabolised only slowly in the human body, and can therefore tend toaccumulate.

Solvents are volatile and therefore can build up in the indoor environment during construction andmaintenance work. Moreover, their emission can continue even after occupancy, and thus add to the load ofother solvents and organic chemicals in the environment from dry cleaning, aerosol propellants, correctionfluid, cigarette smoke and so on.

The World Health Organization classifies organic chemicals as Very Volatile (VVOC), Volatile (VOC), and

SemiVolatile (SVOC). The VVOCs are a fairly small group of which, among building materials, formaldehydewhich is a gas is the most important member. The VOCs are a much larger group, of growing size; theyinclude the binders in plastics and other polymeric materials and the large group of solvents used in themanufacture of paints and varnishes. The semivolatile materials, SVOCs, consist largely of pesticides whichare also very numerous. A fourth category of organic compound which has significant hazards is particulateorganic matter (POM) in the form of dust. Building materials are, however, not a significant cause of POM inthe indoor environment. The classes of substances, their characteristics and uses, based on the World HealthOrganisation (WHO) data, are summarised in table 7 (5, 30).

Table 7. Classification of organic compounds in the indoor atmosphere and their sources.

Description Abbreviation Boiling pointrange (OC)

Main example Principal uses

Very volatile organiccompounds

VVOC 380 Dust Carpets, ventilation ductwork

Source: Crowther, D. (1994). Buildings and Health, Ph.D. Thesis, University of Cambridge,UK, and WHO (1990). Indoor Environment: Health Aspects of Air Quality, Thermal

Environment, Light and Noise, UNCHS/UNEP/WHO


WHO and national authorities, such as American Conference of Government Industrial Hygienists (ACGIH)have set limits for industrial exposure. The Threshold Limit Values (TLV) set by ACGIH for some of the moreimportant solvents are shown in table 8. Guidelines recommended by WHO regarding ambient and indoor airwould be appropriate for domestic exposure, because of the increased time of exposure, and the greatersusceptibility of some occupants such as small children and the elderly. Table 8 also shows some domesticair levels taken from a variety of studies (31,32). It will be seen that all are far below the Threshold LimitValues prescribed.

Table 8. Threshold Limit Values (ACGIH) and recorded domestic air levels for some solvents used inconstruction.

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Solvent Threshold limit value (ACGIH) (mg/m3) Typical domestic air level (mg/m3)

Aromatic hydrocarbons:

Styrene 213 0.0027

Toluene 188 0.01 0.6

Xylene 434 0.01 0.14

Aliphatic hydrocarbons:

nhexane 176

Methyl nbutyl ketone 20Chlorinatedhydrocarbons:

Dichloromethane 174 5

Carbon tetrachloride 31 0.014

Source: Ray, D.E, (1992). Hazards from Solvents, Pesticides and PCBs in Leslie, C.B. andLunau, F.W., Indoor Air Pollution: Problems and Priorities, Cambridge University Press,Cambridge, UK, and ACGIH (1994). 19941995 Threshold Limit Values for ChemicalSubstances and Physical Agents and Biological Exposure Indices.

During occupancy, the key consideration is not the exposure or limit value of any one organic chemical but theexposure to all volatile chemicals. While exposure to individual organic chemicals in the indoor atmospheremay be acceptably low, the combination of numerous gases and vapours at low concentrations can haveirritant effects. Measurements by Molhave (26) of the emissions of solvent gases and vapours from 42building materials showed that about 80 per cent of the compounds identified in the air around the materialswere known or suspected mucous membrane irritants. When combined with other gases in an indoorenvironment, and combined with other environmental factors such as sound, temperature, humidity, theseorganic chemicals are regarded as being largely responsible for the condition known as sick buildingsyndrome. Molhave (26), based on experiments on people exposed to different levels of exposure, suggeststhat concentrations of total volatile organic compounds less than 0.16 mg/m3 may be expected to cause nomucous membrane irritation, while concentrations above 5 mg/m3 are found to cause irritation. In theintermediate range, irritation may occur if promoted by other environmental exposures. Molhave (24) hassubsequently proposed an approximate doseresponse table for airborne VOCs (Table 9).

Table 9. Draft dose response table for airborne VOCs.

Total VOCs (mg/m3) Possible reactions Exposure class

25.0 Additional neurotoxic effects Toxic range

Source: Molhave, L. (1990). Volatile Organic Compounds Indoor Air Quality and Health,Indoor Air 90, Vol. 5, pp. 447452

At present there are no national or international indoor air criteria for new buildings but in some areas, theyare beginning to be developed. In the state of Washington, United States of America, for example, emissionrates for office furniture workstations must be such that the resulting air concentrations in the building are lessthan those shown in table 10 (34).

Table 10. Emission limits for office furniture workstations set by the State of Washington, United States ofAmerica.

Substance Air concentration limit

Formaldehyde 0.05 ppm (0.06 mg/m3)

Total VOCs 0.50 mg/m3

Total particulates 0.050 mg/m3

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Source: Tucker, W. (1990). Building with Lawemitting Materials and Products: Where Do WeStand?, Indoor Air 90, Vol. 3, pp. 251256.


While the solvents are in use, during construction activity, levels will clearly reach much higher values over ashort period of time. Where solvent borne paints, have been specified, measures must be taken to ensureventilation or solvent extraction sufficient to reduce solvent vapour levels below the occupational exposurelimits. Where this is not practicable the operators must be provided with suitable respiratory protection.

Protective clothing should also be provided to workers. Workers too need to be provided with health andsafety information about the hazards of the solvents including the minimum requirements for safe use andexposure control to protect their health, the chemical ingredients, the short and longterm health effects,firstaid information, and storage and transport requirements.


There are limited options at present for the substitution of volatile organic chemicals in paints and otherfinishes. Alternative waterbased paints are available which reduce the quantity of organic chemical solvents,but although advertised as environmentally friendly, they do contain significant quantities of organic solventsand a range of other hazardous chemicals. Solvents based purely on natural products do exist (35) but arenot manufactured yet in large quantities and paints based on them are not commercially available.

F. Formaldehyde


Formaldehyde is a major chemical building block in polymer chemistry, with numerous applications in themanufacture of construction products. It is used as a component of ureaformaldehyde foam insulation and isalso present in many timber products as a component of glues and resins used in the manufacture ofchipboard, plywood and furniture. Formaldehyde is used is now worldwide. For example, production in theUnited States of America alone exceeds 4 million tones per year (36) about half of which is used for theproduction of ureaformaldehyde and phenolformaldehyde resins and in foam insulation.

With a boiling point of 19C, formaldehyde is highly volatile at room temperatures, leading to the possibilityof high concentrations in the indoor environment. It has a strong pungent odour, which acts as a warningagainst prolonged exposure to high concentrations. Moderate levels of exposure have irritant effects to thenose, throat, lung and eyes; at higher levels of concentration for prolonged periods (such as those associatedwith workers exposed to formaldehyde in the workplace) pathological changes to nasal mucosa have beenreported (36). Allergenic skin reactions have also been reported in men chronically exposed toformaldehydecontaining materials. Finally, in high concentrations, the inhalation of formaldehyde is apotential carcinogen on the nasal mucosa: according to IARC (20), formaldehyde is probably carcinogenic tohumans.


Data on acute toxicity are mainly from epidemiological studies of occupationally exposed populations andresidents of buildings constructed of materials containing formaldehyde, and from controlled human exposurestudies (37). Occupational exposure contributes to total exposure, for example, a high occupational exposure(e.g. in formaldehyde or resin production) of 1 mg/m3 for a 25 per cent timeweighted period would give adaily intake of about 5 mg per day (37).

The possible routes of exposure to formaldehyde are ingestion, inhalation, dermal absorption. Inhalation viaambient air, indoor air, or from smoking is the major route of exposure. Of the three, inhalation of the indoorair is the major route of entry with releases from chipboard and other building and furnishing materialsconstituting the bulk of the exposure (37) Furthermore occupants of prefabricated buildings incorporatingchipboard are likely to inhale 23 times as much formaldehyde as occupants of conventional buildings (37).


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Regulations of different countries now limit workplace exposures to between 0.5 mg/m3 and 2.0 mg/m3; whileSweden has specified domestic maxima to 0.1 mg/m3 for new homes and 0.7 mg/m3 for old homes; indoorconcentrations ranging from 0.1 to 0.8 mg/m3 in houses and mobile homes with urea formaldehyde foaminsulation are commonly found (36). It has been found that 0.5 mg/m3 is sufficient to produce nasal irritation;that the noeffect level is 2 mg/m3; and that at dosages of 5.6 mg/m3, rats developed nasal tumours. There isthus only a small margin between the upper permitted exposure levels and the levels at which carcinogenicityhas been demonstrated.


The highly volatile nature of formaldehyde means that while early concentration in the indoor environmentmay be high, the level of concentration will fall rapidly. For example, the level of concentration within a weekfollowing the application of a floor finish using formaldehyde can fall to less than onesixth of its level shortlyafter application (38). Thus, while workers need protection during application, occupants can effectively beprotected by delaying occupancy long enough for the emission to have reached an acceptable level.Adequate ventilation both during construction and occupation can ensure that unacceptable concentrations donot arise. Respiratory protective equipment should be used whenever necessary. Building codes andproduction and processing regulations should take into account the numerous sources that may contribute toindoor formaldehyde, levels which include: insulating materials, chipboard and plywood, and fabrics. Othersources are cigarette smoke, heating and cooking.

G. Insecticides and fungicides


Pesticides are natural or chemical agents such as insecticides, used to destroy troublesome insects,herbicides for weed control, fungicides to control plant disease, rodenticides and germicides (39). A range oforganic chemicals are in use as insecticides and fungicides for timber treatment. They include dieldrin, lindaneand benzene hexachloride commonly used as insecticides, and Pentachlorophenol commonly used as afungicide (17). There are many others in use (31), and some, such as DDT, which have been widely banned.Table 11 shows some of the most widespread chemicals used.

Table 11. Insecticides and fungicides commonly used for timber treatment and their health hazards.

Chemical Use Health hazards CarcinogenicClassification (IARC)

Occupationalexposure limit

(UK, 1994)

Arsenic InsecticideFungicide

Skin damageSkin/other cancers in humans(class 1 IARC)Damage to nervous system

1 0.1 mg/m3*

Creosote FungicideInsecticide

Skin and eye irritationEye damage

BronchitisSkin/lung cancer

2A None

Dieldrin Insecticide Damage to nervous system(Carcinogen) (class 3 IARC)Poisons through skin

3 0.25 mg/m3

Lindane(gammaHCH)

Insecticide Irritant, allergenDamage to brain/nervoussystemCauses epilepsyPossibly Carcinogenic inhumans (2B IARC)

0.5 mg/m3

Pentachlorophenol

(PCP)

Fungicide Irritant

Damages nervous systemDamages heart, liver, kidneyContains carcinogenic

2B 0.5 mg/m3

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Pesticides of various types are also used in timber pretreatment, posing a potential threat to workers in thoseenterprises, which in some countries commonly operate under a poor state of control. Because of theirpersistence in the environment and damage to all forms of life, pesticides must be treated as hazardous wasteand disposed of with great care. Many of the most serious and widespread cases of pesticide poisoning occuras a result of spills and casually dumping wastes on uncontrolled sites (41).


Specific occupational exposure limits for most of the important pesticides have been proposed by national

authorities. Table 11 shows those set for UK by the Health and Safety Executive (44), which are similar to theThreshold Limit Values proposed for the United States of America by ACIGH (see also table 12). But it hasbeen suggested that domestic exposure levels should be set at a level only 1 per cent of the OccupationalExposure Limit to protect vulnerable occupants.


The number of chemicals in use as pesticides and timber preservatives is huge and growing annually, andmany of their effects are as yet not clearly identified (45). Because of their known toxicity, an internationalcoalition of groups and individuals who oppose unnecessary use and misuse of pesticides, the PesticidesAction Network, has identified the following thirteen pesticides, some of which are used as wood preservativesrequiring strict control (45): Aldicarb, Campheclor (Toxaphene), Chlordane and Heptachlor, Chlordimeform,

DBCP, DDT, the drins Aldrin, Endrin and Dieldrin, EDB, HCH and Lindane, Paraquat, Parathion andMethyl Parathion, Pentachlorophenol, and 2, 4, 5T. All of them are highly poisonous to the nervous system.Since no pesticides are free of potential health hazards if used without proper control, less poisonous woodpreservative treatments, those based on synthetic pyrethroids (e.g. permethrin) and inorganic boroncompounds, should be used. Protective clothing should be worn when treating or handling treated timber. Iftreated timber is machined or sanded an efficient dust extraction system should be used and wastes disposedof safely: if dust extraction is not available, dust masks should be used. In remedial treatment of timber,particularly in poorly ventilated enclosures, operators should be provided with respirators (46). Furthermoreduring treatment the following additional requirements are needed;

mix or dilute products before use in a wellventilated area, away from the general public,and label clearly all containers;

if preservative is to be applied by spray, use a coarse lowpressure jet to avoid creating amist of particles;

do not allow drinking or smoking during treatments or until after the operator has washedand changed clothing, the operator should bath or shower at the end of each days work.After treatment the operator must: ensure that the treatment site is well labelled; issueadequate instructions to exclude occupants for at least 48 hours or until treated surfaces aredry; remove all unused preservative from site and store it safely; safely dispose of anycontaminated materials, such as empty preservative containers; the local waste disposalauthority can advise (47).

There is also a growing school of thought that pesticides are not an efficient long term approach to the

preservative treatment of timber, because they penetrate the timber only to a limited extent, and are graduallylost to the atmosphere. Because of this limited life, the contribution claimed by pesticide manufacturers tostemming deforestation by reducing future demand for timber has been challenged (2). Thus elimination of theneed for pesticides by design is the recommended alternative. The alternative mitigation strategy is toeliminate by design the condition which pesticides are used to treat. Rotting of timbers can only take placeunder conditions of high humidity; it can be reduced or eliminated by:

seasoning timber before use to reduce moisture content below 20 per cent;

ensuring all timber in building is kept at low levels of moisture, through providing ventilationof underfloor and roof spaces;

making use of timber species which are less susceptible to rot; and

reducing the use of the more vulnerable sapwood;

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Likewise, where pesticides are commonly used for protection against termites, they should be replaced wherepossible by the use of physical barriers to entry, or by making use of naturally termiteresistant species (48).

H. Timber


Generally timber present no health hazards in itself. On the other hand, inhalable particulate size maypossess toxic, immunological and carcinogenic properties (11). Respirable dust of any kind can irritate therespiratory system or interfere with mucociliary action; a number of woods are irritants of the skin (e.g. iroko,keruig, afromosia), the respiratory track (e.g., beech, iroko, maple) or the eyes (e.g. yew, tak, satinwood).Some such western red cedar, iroko and mahogany, cause allergic asthma. Other woods are poisonous (e.g.yew and oleander) such that can cause nausea and malaise and affect the heart (49). According to IARC,wood dust is carcinogenic to humans (28). Woods directly implicated are beech, oak, and redwood (49).Furthermore, large quantities of airborne wood dust in an enclosed spare can cause an explosion, and somewood dust will spontaneously combust on contact with certain oils or chemicals.


People most at risk are those exposed to high levels of dust during the sanding and machining processesduring production. Though construction workers are less exposed to wood dust hazards compared tocarpenters, joiners and factory workers, on site fitting with

building materials and health

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