Lead

The relationship between lead poisoning and occupational exposure was established prior to the turn of the century but subsequently forgotten or ignored. Like asbestos, negative health effects were first met with a great deal of scepticism. Now, the recommended allowable levels of exposure are continually decreasing as more and more studies show that what were once thought to be safe levels are harmful. Thus while exposure to lead is slowing the generally accepted requirements for good management practice are tightening.

The switch to lead free petrol is reducing exposure from vehicle sources, however there is growing concern about exposure arising from paint.

Older paint contains up to 50% lead. Older paints were especially designed to chalk off in order to maintain a fresh appearance, and so these paints give a high dust load in the surrounding areas.

The main health problem is exposure to the lead dust. The main groups at risk are workers who refurbish buildings, and also the public and those associated in some way.

Children have been known to receive large doses of lead by their parents wearing lead dust contaminated work clothing home, while recent hospitalisations of children with clinical lead poisoning in Sydney have arisen from exposure to the renovation of old houses. The dried paint dust accumulates in soft furnishings, particularly carpet, and can track into neighbouring areas. Once contaminated, it is very difficult to remove lead dust from a carpet.

Dust contaminated with lead from the paint or flakes of peeling paint can be ingested or inhaled. The finer particles are particularly troublesome.

THE EFFECTS OF LEAD

After absorption of lead through ingestion or inhalation, lead is carried by the bloodstream to the organs of the body. Since lead is a metal it is not destroyed, nor is it altered to a non toxic substance. If the body’s ability to get rid of the lead is exceeded by the dose, lead is deposited in various organs and may cause irreparable damage.

Lead is a cumulative poison. Sub-toxic intakes can affect mental and emotional development, particularly in children.

Lead at very low levels affects the nervous system causing signs such as irritability, shortened attention span, sleep disturbance and hearing impairment. Lead also interferes with the production of haemoglobin and blood cells, and in the body’s ability to detoxify pollutants, as well as with gastrointestinal tract and renal function. Effects on the visual and reproductive systems are now well known. One of the biggest questions related to health effects of lead is whether exposures can cause cancer. Tests have shown lead to be a carcinogen in animals, but there is insufficient information to confirm or refute carcinogenicity in humans.

The evidence of damage by lead at low levels to other organisms in the environment is ever increasing, leading to tighter enforcement of environmental laws with respect to lead.

GOOD MANAGEMENT PRACTICE

In the past it has been common to wait until someone is diagnosed as suffering from the effects of lead before remedial work on a structure is undertaken. Now there is an increasing requirement that good management practice be proactive in assessing whether a potential lead problem exists.

Faced with this, what should a building manager do to protect the parties involved from harm or litigation?

In the absence of information to the contrary one should assume the paint to contain lead. Even at levels as low as 0.25% lead, dust generated by dry sanding or abrasive blast cleaning can produce exposure levels exceeding those which define a "lead task" in WorkSafe National Standard 1012. High contamination of lead in dust can result from removal of paint with levels of less than 1%. Australian Standard AS4361 Part 1 (1995) and Part 2 (1998) Guide to lead paint management covers industrial applications (Part 1) and Residential & Commercial buildings (Part 2). The US Department of Housing & Urban Development (HUD) provides further guidance.

It is advisable to assess the presence of lead in all buildings over about ten years of age and in all outdoor steel structures. If there is lead in excess of 1% of the dried weight of the paint flakes or exceeding 300mg/kg in the dust, 1mg/m2 for interior floors, then a remedial strategy should be adopted.

If the surfaces are in good condition this strategy might be no more than reassessing the situation regularly. For other situations the strategy may vary from overcoating, or localised repairs, or total coating removal and replacement, to demolition. Probably the most common strategy is partial coating removal, recoating, and clean up of affected areas.

HOW SHOULD LEAD PAINT REMOVAL BE CARRIED OUT?

• It is essential to cover all exposed carpet and for workers to wear the correct protective clothing.
• During work the air should be monitored for dust and air-borne lead, and worker blood levels should be checked regularly.
• Paint removal should be by wet methods and dry sanding should be avoided.
• Attention should be given to correct disposal of the collected dust and scrapings and of any potentially contaminated water.

NEW ENVIRONMENT LEAD SERVICES

New Environment is skilled in the specialist requirements and is happy to advise on any suspected problem. We are independent of any contractor or operator and can give independent professional advice.

We provide the following lead control services:

• Surveys, both above and below ground including dust and paint
• Management plans
• Removal or control specifications including worker, heritage building and environment protection.
• Job supervision & clearances
• Project management
• Airborne lead monitoring
• Consultancy