Urban Lead Abatement

In 1987 the National Health and Medical Research Council declared that there were "no benefits of human exposure to lead and that all demonstrated effects of such exposure are adverse". Lead Abatement strategies must be implemented to reduce environmental lead levels and lead exposure. The concept of a "hierarchy of control measures" is a useful model in such an overall management strategy. The closer a control measure is to the source the higher up the hierarchy it is and the more effective it will be.

The first control measure for primary prevention of lead exposure would be to limit its use, followed by substitution of less hazardous substances or processes. Then engineering measures can be applied to reduce emission and dispersal.

At the bottom would be measures which have little impact on the source of the problem. Such as the clean up of contaminated sites or individual measures to minimise personal exposure. (Mason 1993) These may be considered as secondary preventative lead abatement strategies. Both primary and secondary measures are discussed below.

Primary Preventative Lead Abatement

Primary methods of lead abatement involve removing or reducing lead at its source. Perhaps the most important example of this is the removal/reduction of the lead content in petrol however, the physical characteristics of lead make it an attractive material for a variety of applications. It therefore provides large economic benefits to all its users. This, coupled with the fact that lead is an elemental pollutant and can never be removed from the environment completely make total removal of lead as a pollutant impossible. Lead in the environment is cumulative and once present is difficult and expensive to remove.

Lead in petrol represents one of the largest sources of continuing addition to urban environmental lead loads. Lead is added to petrol for two reasons:

1. to raise the octane level; and

2. to lubricate engine valves. (CEPA 1993)

All new cars in Australia since 1986 have been fitted with catalytic converters. The resulting increase in the use of ULP has greatly reduced lead and other emissions. However, while it is estimated that demand for leaded petrol will have decreased to almost zero by 2004 (NRMA 1993), more must be done to reduce urban lead levels because of the serious effects it has on humans especially children.

Other strategies to reduce urban lead loads involve a reduction in the maximum permissible concentration of lead in petrol, the introduction of a tax on lead as an additive, the introduction of a price differential between unleaded petrol and leaded petrol [a one cent differential came into being in Feb 1994], and the introduction of increased stamp duty or registration on leaded vehicles. (CEPA 1993)

It is clear that all the above options have some negative repercussions. Therefore we must question our dependence on private vehicles. The only sure way to reduce environmental lead loads is to reduce total petrol consumption which can only be achieved through a far greater use and extension of the public transport system.

Further Strategies

There are several other common sources of lead to which reduction/abatement strategies can be applied. An important method is through the use of alternative substances in common uses of lead.

1. Thermoplastic insulators can be used as an alternative to lead sheathing. Aluminium, polyethylene and PVC have also been used successfully in countries such as Sweden.

2. Several organic and inorganic substitutes are available for lead based pigments. Iron oxide is suitable in most applications. The use of lead in paint pigments is now banned and cost effective substitutes exist.

3.  Metal alloys such as tin/antimony, tin/silver, or bismuth/tin may be used in solders but cost and performance limitations of these have slowed the phase out of lead solders. Some of these substitute metals may also pose health concerns.

4. Iron and steel shot make adequate substitutes for lead, however there is a loss in performance, higher cost and increased wear on gun barrels associated with these substitutes. It is also difficult to prevent the use of imported lead shot.

5. Some substitutes exist for some applications of glass making and ceramic glazing; however, the majority are costly, prone to problems and of similar health/toxicity concern. (OECD 1991, Mason 1993, Kenworthy & Newman 1993)

Additional primary lead abatement strategies which can be applied to common sources of urban lead (and which in many cases relate to the substitutes listed above) are complex and in some cases difficult to monitor. The worth of these strategies however cannot be questioned in light of the serious nature of lead toxicity. Some of them include:

1. the implementation of standards for metal food containers Five percent of food cans in Australia use lead as a solder. In some cases regulations require that the solder be applied only on the outer side of these containers.

2. the cessation or reduction of the use of brass fittings in plumbing, or the implementation of maximum lead content or a maximum lead leaching rate from these fittings.

3. the control of lead shot and fishing weights by limiting their use in areas of high ecosystem exposure or sensitivity, or banning their use altogether.

4. exposure to lead in products for which no substitutes exist such as lead acid batteries can be limited through deposit refund systems, recycling and the encouragement of technological development in the area of substitutes.

5. the regulation of emissions from industry sources and waste incinerators are also a vital method of controlling lead levels.

6. new uses for lead continue to be identified. Their development should be based strictly on an assessment of net costs and benefits, taking into consideration the global environmental effects of lead. (OECD 1991)

In Australia, an integrated strategy to reduce our exposure to lead will have to cross the boundaries of traditionally disparate jurisdictions, bringing together initiatives in all areas - food, air, soil and other relevant areas. Global co-operation is also necessary because poorer countries tend to suffer higher exposure to lead overall. The OECD and the International Organisation of Consumers Unions state there must be international standards. trade agreements, marketing conventions and international technology transfer to ensure that the lead burden within the global environment can be significantly reduced and is not unduly placed on poorer countries. (OECD 1991)

Secondary Preventative Lead Abatement

Secondary prevention measures must be implemented to reduce exposure to lead which has already accumulated in the environment over the long term.

The main sites of lead contamination include:

• buildings with lead-based paint and their surroundings;

• contaminated soil or accumulated dust from air pollution, resulting from lead in petrol, past poor mining and smelting practices;

• and possibly drinking water from lead pipes.

Abatement measures to address each of these sources of lead poisoning include:

Decontamination of houses, childcare centres, schools, and the local area.

This is a priority in areas frequented by young children and prospective mothers.

Lead abatement may involve:

• the safe removal of ceiling dust;

• wet removal of flaking paint and repainting or re-cladding;

• repairs internally and externally to prevent dust entry (where there is the possibility of continued exposure to air borne lead and dust);

• the removal or cleaning of carpets and soft furnishings.

• the removal and/or treatment of the contaminated layer of soil (usually the top 5cm);

• the replacement of lead piping for drinking water, and/or piping and water tanks with lead solder.

• paving and planting of trees, shrubs and groundcovers to consolidate the soil and provide a barrier between children and soil. Plants also catch air borne lead.

Successful implementation of these measures may require:

• Identification of housing at high risk including public housing which is known to be particularly prone to contamination. In the case of private housing, implementation of an inspection program particularly between buyers and a mechanism for notification of potential purchasers of homes containing lead-based paint and contaminated soil and dust.

•  Mapping cases of lead poisoning to determine 'at risk' areas, especially near potential point sources of lead emission.

• Programs to warn householders of the dangers during renovation and distribution of guidelines for safe abatement techniques.

•  Developing training programs for Environmental Health Inspectors employed by local councils. Training must also be provided for lead abatement workers to carry out decontamination. This must include safe disposal of the contaminated material.

•  An equitable program to reduce lead exposure must ensure funding for household lead abatement with low interest or no interest loans. Such a scheme is in operation in Massachusetts, USA (Executive Office of Communities and Development & Massachusetts Housing Finance Agency). The Australian proposal for reducing lead exposure includes subsidies for temporary accommodation for children during abatement procedures. (Berry et al 1993) World Health Organisation principles for public policy state that special attention must be paid to disadvantaged and high-risk populations. (WHO 1989).

•  Lead abatement for drinking water requires a program of testing for lead in first flush drinking water. Household lead exposure would also be addressed by conducting education programs to inform home handypersons of the dangers in using lead solder in plumbing. (Berry et a11993)

•  Paving and the planting of trees, shrubs and groundcovers. The smelter town of Port Pirie in South Australia has accelerated road and footpath sealing and carried out extensive planting. (Berry et a11993)

Nutrition Programs

To reduce calcium, iron. and zinc deficiencies especially among young children and prospective mothers. Deficiencies of calcium and iron clearly enhance lead absorption. (Goyer 1990) Increasing zinc in the diet reduces tissue accumulation and toxicity of lead. (Cited in Goyer 1990)

This, in particular may require the consideration of socio-economic factors in creating good health and well-being.

Workplace Programs

To ensure that workers exposed to lead in the workplace, including domestic premises where paint, soil or dust is being removed, undertake additional hygiene practices to minimize the transfer of lead to the home. (Heyworth et a11993)

At the workplace the hazard should be concentrated in one area. There are encapsulating methods which can be employed. It may be possible to mechanise and automate hazardous processes. Effective ventilation and control of dust with moisture applications and vacuuming are essential, along with the supervision and maintenance of these controls. (OECD 1991)

Disseminate guidelines for lead poisoning detection and prevention to health professionals.

Medical professionals may readily detect cases of high dose acute lead poisoning but may be unaware of the effects of chronic low dose exposure. Guidelines concerning this must be user-friendly and would easily be disseminated through the Department of Health, Community Services, Local Government, Professional Bodies and Universities. (The LEAD Group)

Community Support Program

Education and awareness campaigns to detail the above and other potential sources of exposure including lead shot, lead in children's toys, paints and crayons; fishing weights, curtain weights, pottery glazes, lead crystal, makeup, incinerators, and traditional medicine. (Berry et al 1993)

The provision of family support and counselling to those affected and undergoing abatement procedures is essential. (Calder & Collings 1989)

The WHO Charter on Environment and Health outlines the involvement of individuals and communities in consultation and management as an essential strategy to prevent adverse impacts on health. (WHO 1989)

Screening and Monitoring Program

It is essential to develop a screening and monitoring program to identify sites of possible lead contamination and to ensure that abatement measures are having the desired effect. (Heyworth et al 1993)

Biological monitoring of blood lead levels in children below the age of seven years at six monthly intervals is necessary to determine changes before, during and after abatement interventions. (Calder & Collings 1989)

The prevention of lead poisoning requires the involvement of the whole community in ensuring the implementation of primary and secondary measures. If these measures are successfully implemented the incidence of lead poisoning should decrease and tertiary measures including medical treatments will become less necessary.

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