Health experts are calling for new national guidelines amid fears that up to 100,000 young Australian children could have dangerously high levels of lead in their blood.
The experts say current guidelines on lead levels must be updated urgently in light of new figures based on analysis of US exposure rates and published in the latest Medical Journal of Australia (MJA).
In a letter to the MJA, Mark Taylor of Sydney's Macquarie University, Chris Winder of the Australian Catholic University in Sydney and Bruce Lanphear of Canada's Simon Fraser University, say 100,000 Australian children aged up to four could have blood lead levels linked to health problems.
These include behavioural problems and low IQ.
Guidelines recommending blood lead levels of below 10 micrograms per decilitre of blood introduced by the National Health and Medical Research Council (NHMRC) in 1993 are "increasingly obsolete", the researchers say.
"New and overwhelming evidence indicates that even levels below 5 micrograms per decilitre are associated with a range of adverse health outcomes, including decreased intelligence and academic achievement, sociobehavioural problems such as attention deficit hyperactivity disorder, learning difficulties, oppositional and conduct disorders and delinquency.
"Importantly, the greatest relative effects on IQ occur at the lower blood lead levels."
They recently held a forum on childhood lead toxicity at Macquarie University and suggest not only that the NHMRC goal is lowered, but also that ways of identifying sources of lead exposure need to be improved.
There is no recent data for lead levels in Australian children, so the figures were estimated using US exposure rates and applying them to the Australian population.
According to advocacy organisation The Lead Group, one of the main sources of lead is old paint from buildings built prior to 1970.
They estimate 3.5 million homes have lead-based paint, which is often sweet tasting and therefore appeals to young children, who will pick at it and eat it.