UNITED NATIONS	HS
	Commission on Human Settlements	Distr. GENERAL HS/C/15/2/Add.5 21 December 1994 ORIGINAL: ENGLISH
Fifteenth session Nairobi 25 April - 1 May 1995 Item 4 of the provisional agenda        Activities of the United Nations Centre for        Human Settlements (Habitat):        progress report of the Executive Director
BUILDING MATERIALS AND HEALTH
Report of the Executive Director

Introduction

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1. In its resolution l4/l6 of 5 May 1993, the Commission on Human Settlements requested

"the Executive Director … to explore the possibility of drafting an informative document on: (a) such building materials in the housing sector that are harmful or potentially harmful to peoples health and the environment: and (b) of possible alternative building materials that could substitute for such materials, and to present that document to the Commission on Human Settlements at its fifteenth session".

The purpose of this report is to provide information on: ways in which building materials contribute to environmental stress and health hazards: and the means available for control or mitigation of their adverse health and environmental impacts. Challenges to the control strategy are indicated, and strategic actions by key actors are given,

2. Chapter 7, Programme area G: "Promotion of sustainable construction practices", of Agenda 21, adopted by the United Nations Conference on Environment and Development, recognizes that the activities of the construction sector can be a major source of environmental damage and that the use of building materials cart be harmful to human health. It, therefore, recommends policies, technologies and an exchange of information to enable the sector to meet human settlements development goals, while avoiding its harmful effects to human health and the environment. In addressing adverse environmental effects produced by construction activities in general, and building materials in particular, the Centre has already issued a publication entitled Development of National Technological Capacity for Environmentally Sound Construction (HS/291/93E). The publication, which has been widely distributed, identities ways in which construction activities contribute to different areas of environmental stress, and considers means available for reducing adverse environmental impacts through improved technologies and through design and modified practices. The present report, therefore, focuses exclusively on the health hazards of building materials and their control. There are six classes of materials which have been considered, namely: asbestos, metals, solvents, insecticides and fungicides, radon, and earthen and traditional materials. For a more detailed treatment o f the subject, reference is invited to the information document entitled "Building materials and health" (HS/C/15/INF.8) which is to he circulated for the fifteenth session of the Commission.

3. Health risks usually result from exposure to harmful environmental conditions in the extraction, production and use of building materials, and the disposal of related waster. These conditions include exposure to dust, fumes, gases and vapours, and toxic metals. The interaction of these tractors and the human organism can he hazardous to human health in a variety of ways, including respiratory diseases such as asthma, heart disease, cancer, neurological disorder, or poisoning. The table provides a summary of building materials, their areas of application and related health hazards, and mitigation strategies on the hazards- and substitute materials.

I. Hazardous building materials

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4. Asbestos is used for lightweight insulation and lagging, as a filler in plastics and roofing felts, for sprayed steel coatings, pipe seals, as an additive to cement products, in board products and ceiling tiles, and for high-temperature applications. Employment in the asbestos industry has shown a strong correlation with a number of health problems such as asbestosis. Lung cancer, and malignant tumours in the lining of the chest cavity or abdomen. Health risks are posed by exposure to airborne respirable particles which can be deposited in the lung tissue. The major risk is mainly to construction, demolition and maintenance workers, but also to building occupants when the material is cut or drilled, or when degradation occurs by physical abrasion or chemical attack, releasing respirable particles into the aura Building occupants can be protected by confining the material in sealed components. Many materials have also been developed as substitutes for asbestos-based products, a number of which use artificial fibres. Non-fibrous alternatives include non-toxic metals, soft wood and clay products. Vegetable fibres can also he used as substitutes. Studies on artificial fibres (e.g., glass wool, rock wool, slag wool), however, indicate that not all respirable-size artificial fibres are biologically inert and health hazards posed by them require thorough investigation. The mitigating strategy for existing buildings should focus on establishing and enforcing strict regulations for engineering control measures and safe work practices in the handling of asbestos, and sealing all installed components containing asbestos. The substitution of asbestos should he considered where safe control cannot be assured. For new buildings, non-fibrous alternatives to asbestos should be considered first. Fibrous substitutes, particularly artificial fibres, whenever considered should he evaluated on a case-by-case basis for possible health hazards.

5. Metals are used in the construction industry in their metallic form or as compounds, primarily in paints and other finishes. Most metals are harmless; in fact, dietary intake of many metallic elements is essential to health. Risks, however, result from excessive intake of certain metals. The principal building-related sources of health risks are soluble metallic salts in the water supply, from the use of metals in pipework and joints, storage tanks, and roof flashings, gutters and downpipes where run-off water is used for cooking or drinking, and paint flakes, which may he ingested. Metals of potential concern are cadmium, chromium and lead. Their health risks include hone damage and kidney malfunction, skin diseases, inflammation of the larynx and perforation of the nasal septum, liver damage, lung cancer and poisoning. All three metals present risks as they are used in compounds of paints. Lead has more uses in roofing and associated works, water supply pipes, glazing bars and as an additive in linseed-oil putty. Further health risks are experienced in cadmium-plated fittings and chromium metallic finishes. Children are particularly liable to be affected by toxic metallic compounds in paints as they spend a large part of their time at floor level, where they acre susceptible to patina and solder flakes in household dust. Furthermore, some children develop a condition known as "pica", characterized by a craving to eat non-food substances. Paint flakes can be a favourite meal. To minimize risks to exposure, toxic meal-based patinas should never be used in situations accessible to children: paintwork should be kept in good condition and when removing old toxic metal-based paints it is advisable to use chemical strippers rather than mechanical methods: and all debris from stripping such old paints should be safely cleared and disposed of. Substitutes include non-toxic metals, plastics, synthetic rubber and timber: for paints, it is recommended to use vinyl-based paints, polyurethane varnishes and water-based paints.

6. Solvents - Organic solvents are very widely used in construction as key ingredients of adhesives, paints, flooring materials and mastics. The most commonly used solvents include white spirit, toluene, xylene, trichloroethane, styrene and carbon tetrachloride. Paints, glues and lacquers contain toluene, methyl-n-butyl ketone, n-hexane and xylene; patina strippers and solvents contain white spirit and dichloromethane; and expanded plastics contain styrene. All these materials are volatile and therefore can build up in the indoor environment during construction and maintenance work. Their emission can continue after occupancy, and thus add to the load of other solvents and organic chemicals in the environment from dry cleaning, aerosol propellants, correction fluid, cigarette smoke and so on. If inhaled in sufficient quantity, all solvents can produce sedation effects ranging from slowed reaction time and decreased vigilance to anaesthesia. Some produce irritation to the eyes, nose and throat: several can cause liver damage and damage to the nervous system.⁽¹⁾ While the solvents are in use during construction activity, levels will clearly reach much higher values over a short period of time. Adequate protection of workers from excessive inhalation through proper ventilation and, if necessary, protective clothing are therefore recommended. During occupancy, the key consideration is not the exposure or limit value of any one organic chemical but the combined exposure to all volatile chemicals. There are limited options at present for the substitution of volatile organic chemicals in patinas and other finishes. Alternative water-based paints are available which reduce the quantity of organic chemical solvents, but although advertised as environmentally friendly, they do contain significant quantities of organic solvents and a range of other hazardous chemicals. Solvents based purely cm natural products do exist,⁽²⁾ but are not manufactured yet in large quantities, and paints based on them are not commercially available.

7. Insecticides and fungicides - A very large group of organic chemicals are in use as pesticides and fungicides for timber treatment. They include dieldrin, lindane and benzene hexachloride, commonly used as insecticides, and pentachlorophenol, commonly used as a fungicide.⁽³⁾ All of these chemicals are toxic to the organisms they are intended to combat. If inhaled or ingested in sufficient quantities, they can also be hazardous to the health of those involved in applying them, particularly when used in the form of sprays. Some can cause skin reactions. Several of them are known to be carcinogenic.^(4,5) The principal risk from insecticides and fungicides is to construction workers, and to those involved in the remedial treatment of timber in existing buildings which have been degraded, and in poorly ventilated roof spaces.⁽⁵⁾ While exposure to individual organic chemicals in the indoor atmosphere may be acceptably low, the combination of numerous gasses and vapours at low concentrations can have irritant effects. One mitigation strategy is to eliminate by design the condition which pesticides are used to treat. Rotting of timbers can only take place under conditions of high humidity: it can be reduced or eliminated by seasoning timber before use to reduce moisture content; by ensuring all timber in building is kept at low levels of moisture, by providing ventilation of underfloor and roof spaces, by making use of timber species which are less susceptible to rot, and by reducing the use of the more vulnerable sapwood. Likewise, where insecticides and fungicides are commonly used for protection against termites, they should be replaced where possible by making use of naturally termite-resistant species.⁽⁶⁾

8. Radon is a radioactive emission which has been identified as the likely cause of increased rates of lung cancer among uranium miners. Radon substances are present in all surface sods and rocks, but in concentrations which vary regionally as a function of the relative abundance of the parent uranium. It is capable of diffusing through soils and, to a less extent, building materials, thus entering the internal envelope of a building. Building materials may also constitute a possible source of radon: these include natural stones, principally those of igneous or volcanic origin, industrial wastes like phosphogypsum (a byproduct of the manufacture of phosphate-based fertilizers) and blast-furnace slag. A large number of building materials have been tested particularly in Europe, the United States of America and the former Soviet Union⁽⁷⁾ and radon emission rates and the annual radiation dose to an occupant of the building constructed with the materials under consideration have been estimated. Over a lifetime of exposure, it is estimated that the risk of developing cancer due to radon emanation from building materials is only a fraction of 1 percent. However, such a risk may increase in particular circumstances where materials with very high radioactive contents are used or where the relative risk for an individual are enhanced by factors such as smoking.⁽⁸⁾ Substitute materials are those with no or low levels of radon emission like sedimentary stones (sandstone or limestone). Alternative walling constructions could use bricks, adobe, timber training or concrete blocks with sedimentary rock aggregates. Substitute materials for plastering could include cement-sand render in replacing gypsum-based mortar. For existing buildings, however, the most effective mitigation strategy is to isolate radon-omitting materials from the indoor environment. This could be achieved with a dense laver of internal render. Moisture barriers and especially air-tight barriers such as polythene sheet can be incorporated in the wail construction.

9. Earthen and traditional materials include earth, stone, timber and thatch. Generally, where the dwelling is made from low-strength masonry, the walls and floors are prone to cracking as the earth dries, providing suitable dark spaces for disease arthropods to hide. Roofs made from thatch also provide plentiful hiding spaces for arthropods and can be a cause of fire hazards. Furthermore, traditional flat roofs [trade of poles piled with wood and covered in a layer of mud, provide am ideal habitat for arthropods. Such arthropods include houseflies, cockroaches, triatomine bugs, domestic ticks and bed bugs. A number of these arthropods are carriers of human disease pathogens. Their related diseases are particularly prevalent in tropical areas, since higher temperatures enable the vectors to breed more rapidly. Perhaps the most important disease carried by the vectors is the American form of trypanosomiasis, or Chagas disease, which is transmitted by the bites of file triatomine bug.⁽⁸⁾ People infected with Chagas disease are often unable to work because of the damage to their cardiovascular system. Methods available to eliminate infestation include spraying the walls and roofs with insecticides, plastering with smooth durable materials, and replacing walls, floors and roofs with smooth crack-free materials such as toed-clay materials, concrete products and aluminium- and iron-based materials for roofing.

II. Challenges for control of hazards

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10. The challenges in promoting practical strategies for control of hazards associated with building materials include;

• (a) Insufficient knowledge regarding the nature and severity of health hazards of some of the materials. Moreover, the health effects of chronic low-level exposure to many materials remains very difficult to assess.⁽⁹⁾ This ruses issues such its: the problem of the burden of proof to make legal-political decisions; differences of perception of what is just or fair in public policy and what are the appropriate threshold limits in the public eye, whether to prohibit the use of a material until if is proven safe, or to allow ifs use, until it is proven harmful. Furthermore the public is not adequately informed of the health hazards of building materials.
• (b) Manufacturers of building materials have difficulties in balancing immediate costs of health improvements against long-term benefits. Uncertainty about future benefits make it less likely that action would he taken.
• (c) Designers often have n number of conflicting criteria to resolve. They need to balance the risks to health against the cost of providing protection; and the need for adequate ventilation for a healthy indoor environment, with the need to reduce the energy consumed in heating or cooling incoming air.
• (d) One of the control strategies involves the use of alternative materials. Alternatives, however, are not available in all situations. Also alternatives which were at one time recommended could have their own separate hazards, particularly when the substitution option is new and untested. Consequently, avoidance of one type of risk may simply introduce a different and perhaps less understood one.
• (e) There are no regulatory mechanisms on some of the hazards, partly due to lack of information or due to economic considerations. Where regulations exist, the administrative costs and bureaucracy involved in implementation act as severe disincentives to their application. In many countries, regulations are still far behind current practice.
• (f) Inadequate collaboration among the broad range of stakeholders and actors, particularly among research institutions. the construction industry and regulatory bodies.
• (g) Additional features for developing countries, include: lack of workers and local training opportunities: poor information base and inadequate dissemination of available information; lack of appropriate policies; existing laws do mot cover all aspects of health and workers' welfare and are biased towards curative rather than preventive health care.^(10,11)

III. Control strategy

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11. It is not intended to propose within the confines of this paper, a specific approach for the control of each of the discussed building-materials-related health hazards. However, the following general health-hazard management approach is recommended:

• (a) Phase out hazardous materials and processes and use safer alternatives;
• (b) In cases where phasing out is mot possible and there are no safer options, hazardous exposure levels should be contained through engineering measures;
• (c) Those at risk should be protected by the use of protective equipment, application of safe work practices, and provision of medical services;
• (d) Arrange for health insurance policies to cover those at risk;
• (e) Continuously monitor the risk and provide medical surveillance of workers.

The success of these measures requires the coordinated action of the industry, governments and international agencies to ensure that the problems of human health related to building materials and the built environment are linked to the Global Strategy for Shelter to the Year 2000 within the framework of sustainable development.

IV. Roles of key actors

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12. The information document, "Building materials and health" (HS/C/15/INF.8), identities roles to be played by key actors in health-hazard control. Briefly, the roles for the producers and users of building materials are as follows:

• (a) Manufacturers should take measures to avoid the production of hazardous materials and ensure the protection of workers and users of their products;
• (b) Designers should specify sate materials and design indoor environments so that concentrations of hazardous substances do not accumulate;
• (c) Owners of buildings should ensure that they use safer materials and processes in the construction of buildings, and during maintenance, refurbishment, demolition and disposal of wastes;
• (d) Builders should ensure that they offer protection to workers during construction, maintenance, demolition and disposal of wastes;
• (e) Research organizations should work towards bridging the knowledge gap regarding health aspects of building materials;
• (f) Professional organizations and nongovernmental organizations should spearhead health advocacy, provision of information and standards, promotion of technology development and diffusion, health education and training and should monitor the implementation of regulatory and control programmes;
• (g) Workers themselves should assume a greater role in self-monitoring the quality (if their own work environment and should act responsibly by; taking reasonable care of their own health and safety and of those who may be affected by their activities, and comply with occupational safety and health standards and all statutory provisions which me applicable to their own activities and conduct.

13. National and local governments have a crucial role to play in the control of hazards associated with building materials by providing economic incentives and taking regulatory and non-regulatory actions appropriate to specific country contexts. Economic incentives should be directed to popularize the alternatives available for the substitution of materials harmful to health and the possibility of introducing product changes should be considered to discourage the use of harmful materials. Local governments should ensure that building regulations are made more restrictive to the use of harmful materials in buildings. Non-regulatory actions may include government sponsorship of research, the promotion of standards and specifications, and the organization of demonstration projects.

14. The cost and specialized nature of the work involved in identifying, understanding and controlling health hazards related to building materials is such that international sharing of know-how is essential. UNCHS (Habitat) is currently implementing a project with Danish International Development Agency assistance which investigates the effects of building materials among other things, on health. The findings of this study should be available by the end of 1995. The International Labour Office, the United Nations Environment Programme (UNEP) and the World Health Organization (WHO) have jointly published the Environmental Health Criteria documents. WHO has also, in conjunction with UNEP, commissioned a report on the indoor environment⁽¹²⁾ which sets out aN action plan for improving indoor environmental conditions in dwellings worldwide. In particular, international action should focus on facilitating the formulation of housing policies sensitive to health needs, and on stimulating and supporting, international, regional and national cooperation and action, e.g., in tire harmonization of international standards and legislation with regard to the manufacture and use of building materials and in the application of relevant protocols and newly developed standards.

Notes

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(1) Ray, D. E., Hazards from solvents, pesticides and PCBs" in Leslie. G. B., and Lunar. F. W., Indoor Air Pollution: Problems and Priorities (Cambridge, Cambridge University Press, 1992).    [Go back to text]

(2) Ashworth, J., "My paints", Architects' Journal, 27 October 1991, p, 62.    [Go back to text]

(3) Curwell, S.R., and March, C.G., Hazardous Building Materials: a Guide to the Selection of Alternatives (London, E. & F.N. Spon, 1996).    [Go back to text]

(4) Robertson, A., “Gases-vapour and mists", in Building and Health: the Rosehaugh Guide to the Design, Construction ,and Management of Buildings (London, RIBA Publications, 1990).    [Go back to text]

(5) London Hazards Centre (LHC), Toxic Treatments: Wood Preservative Hazards at Work and in the Home (London, LHC, 1989).    [Go back to text]

(6) KBP Architects. Rammed earth structures: a code of practice (draft document, 1994).    [Go back to text]

(7) Nuclear Energy Agency, Exposure to Radiation from the Natural Radioactivity in Building Materials (Paris, Organisation for Economic Co-operation and Development, 1979).    [Go back to text]

(8) Spence. R.J.S., Cambridge Architectural Research Limited (U.K.). "Building materials and health" (unpublished draft prepared for the United Nations Centre for Human Settlements (Habitat), September 1994).    [Go back to text]

(9) Ashford, N.A., Crisis in the Workplace, Occupational Disease and Injury (Cambridge, MA, The MIT Press, 1976).    [Go back to text]

(10) World Health Organization (WHO), Technical Report Series 718: Environmental Pollution Control in Relation to Development (Geneva, 1980.    [Go back to text]

(11) East African Newsletter on Occupational Health and Safety, Supplement 1/1990, Proceedings of the East African Regional Symposium on Regulations and Control in Occupational Health and Safety, Zanzibar, Tanzania, 1-7 December 1999.    [Go back to text]

(12) WHO (1990), Indoor Environment: Health Aspects of Air Quality, Thermal Environment. Light and Noise, (Geneva UNCHS (Habitat)/UNEP/WHO, 1990).    [Go back to text]