Lead is still poisoning children, study shows

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Indy Lifestyle Online

Efforts to cut the levels of lead in the environment over 30 years have failed to protect children from the damaging effects of the neurotoxic poison, research suggests. Despite lead-free petrol and the phasing out of lead paint and lead pipes, one in 10 children in the UK may still be exposed to levels high enough to cause brain damage affecting IQ.

Efforts to cut the levels of lead in the environment over 30 years have failed to protect children from the damaging effects of the neurotoxic poison, research suggests. Despite lead-free petrol and the phasing out of lead paint and lead pipes, one in 10 children in the UK may still be exposed to levels high enough to cause brain damage affecting IQ.

American researchers have found children suffer intellectual impairment at blood-lead concentrations well below the level of 10 micrograms per decilitre generally regarded as safe. The findings indicate lead damage at the lowest levels of exposure, increasing only slightly as blood levels rise above 10 micrograms. They suggest that for 30 years scientists investigating the damaging effects of lead have been looking at the wrong victims.

Instead of focusing on those with high levels of lead in the blood, where an increase in the dose makes little difference, they should have examined those with the lowest levels, where a small increase can cause a big drop in IQ.

Researchers from Cornell University in New York who measured the lead levels in 172 children between birth and the age of five found that the IQ scores of children with blood-lead levels of 10 micrograms per decilitre, the safe level in the US, were seven points lower than for children with 1 microgram per decilitre. An increase in blood-lead levels above 10 micrograms to 30 micrograms was associated with a further IQ decline of two to three points.

Richard Canfield, lead author of the study in the New England Journal of Medicine, said: "In our sample, most damage to intellectual functioning is at blood-lead concentrations below 10 micrograms." Charles Henderson, his co-author, said: "Because most prior research focused on children with higher exposures, we suspected those investigators could estimate only the amount of additional damage after blood lead has reached 10 micrograms per decilitre, unaware more damage may be at lower levels."

The findings raise urgent questions about industrial pollution, a main source of lead in the environment, and the safety of children in houses with lead water pipes or where lead paint has chipped or is being removed. In toddlers, who are most vulnerable to lead poisoning, the biggest risk is thought to be from lead particles from chipped paint or DIY work that settle on toys, which are often chewed.

In the US, one in 50 children has lead levels above 10 micrograms per decilitre and nearly one in 10 has a level above 5 micrograms. No comparable study has been done in the UK, said Virginia Murray, director of the London chemical hazards and poisons division of the Health Protection Agency. "Lead is a forgotten poison," she said.

A report by the Chemical Incident Response Service said: "The dangers of clinically asymptomatic lead poisoning in children have become increasingly clear, with longitudinal studies of development from birth to adolescence showing irreversible cognitive damage at levels considerably lower than those associated with overt symptoms."

Dr Murray said: "There should be a national surveillance system with agreed levels of lead in the blood at which action should be taken."

A spokeswoman for the Health Protection Agency said blood-lead levels had been falling in the UK population and were now mostly between 1 and 3 micrograms per decilitre.

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