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To: LLCF who wrote (31921)	4/20/2003 9:18:14 AM
From: maceng2	Read Replies (2) \| Respond to of 74559

so did Einstein Thanks for the excellent quotes and links. IQ update on the effects of lead. ================================== newscientist.com 'Safe' lead levels still damage children's IQ 22:00 16 April 03 NewScientist.com news service Even exposure to "safe" amounts of lead damages children's intelligence, reveals a new study. In fact, lead's effect on intelligence is proportionately greater at low blood levels, meaning most of the damage is caused before the maximum level is reached. "Our study shows there is no discernible threshold for the adverse effects of lead exposure," says Bruce Lanphear, a pediatrician at the Children's Hospital Medical Center in Cincinnati, Ohio. The World Health Organization and the US Centers for Disease Control both say blood levels above 10 micrograms of lead per deciliter of blood put children at risk of cognitive damage. But the new research shows that children with levels at that limit also suffer significant intelligence loss. Children with blood lead levels of 10 micrograms/deciliter had IQs that were 7.4 points lower than children with levels of 1 micrograms/deciliter. When the levels rose from 10 to 30 micrograms/deciliter, intelligence dropped by only another 2.4 IQ points. Paint and pipes Children in North America and the UK are exposed to lead mostly through old paint and lead water pipes. The CDC says only two per cent of US children under five years old exceed the WHO/CDC lead limit, but 10 per cent have levels between 5.0 and 10 micrograms/deciliter or higher. "I think it's an excellent study. I don't think we can say there is a safe level of exposure," says David Bellinger, a neurologist at Harvard Medical School, and a member of the CDC Advisory Committee on Childhood Lead Poisoning Prevention. Researchers tested lead levels in children from six months to five years of age, and tested their intelligence at three and five years. They adjusted for factors like household income and maternal intelligence and education. It is not clear why damage should be proportionately greater at lower exposure levels. Lanphear speculates that cells may develop protective mechanisms once lead exposure reaches a certain level. Journal reference: New England Journal of Medicine (vol 348, p 1517) Kurt Kleiner