By Peter Boyle
MELBOURNE — A just-completed conference of international experts has confirmed that relatively low exposure to lead pollution can permanently damage intellectual development in children.
The October 5-9 gathering of the world's top scientific experts in the field agreed children with sustained blood-lead levels of more than 10 micrograms per decilitre (ug/dl) could suffer an average IQ loss of 2-3 points for every 10 ug/dl increase. It is estimated there are 20,000 children with blood-lead levels exceeding 20 ug/dl in Australian cities, particularly in Newcastle, Port Pirie, Broken Hill and Wollongong.
While several studies over the past decade have indicated a link between child mental development and exposure to lead from vehicle exhaust fumes, lead-based house paint (now banned) in older homes and industrial pollution, there has not previously been an official consensus. Two of about 10 detailed studies around the world strongly disputed the link, but both were funded by the lead industry.
Establishing links with IQ levels was difficult because people with long-term and high lead exposure (due to living near busy roads or industrial plants) usually belonged to socioeconomic groups which recorded lower than average IQ scores, the scientists said.
The cautious consensus (some studies indicated a greater loss of IQ) of this meeting of the International Program on Chemical Safety working group of the World Health Organisation is an important step forward, says Adelaide University's Professor Tony McMichael, who headed a study of Port Pirie, the most comprehensive so far in Australia.
While scientists at an end-of-conference public briefing stressed that lead pollution was persistent but declining in all industrialised countries, community activists were concerned that inadequate action was being taken in Australia. Elizabeth O'Brien of the Sydney-based Lead Education, Abatement and Design group (LEAD) told Green Left Weekly Australian authorities were not taking urgently needed action, while scientists argued over fine points. She was also concerned that the conference findings could be used to reduce existing standards.
In the United States, the dangers of relatively low-level lead contamination were recognised and acted upon as early as 1986. US standards require community action when blood-lead levels of 10 ug/dl are detected, individual action (counselling or reduction of exposure) for 15 ug/dl and urgent medical action for 24 ug/dl.
But in Australia, the National Health and Medical Research Council's 70> is 25 ug/dl (it was 30 ug/dl until 1985). The NHMRC, a federal government body, will review its levels of concern after another two IPCS workshops, in Melbourne this month and Brisbane next February. Dr John Loy of the NHMRC promised thorough community consultation in the process. Greenpeace's Lynn Thorstensen says Australia should adopt US standards.
O'Brien was also concerned at Australia's relatively poor record on reducing leaded petrol. She said 30% of drivers on Australian roads should be using lead-free petrol but were not, and Australia was doing worse that the US and every western European country except Portugal.
Colleen Hartland of the Melbourne Hazardous Materials Action Group says authorities even refused to act in cases of very high levels of heavy metal contamination, such as housing projects on old industrial sites.