Lead's lasting legacy.

Lead's lasting legacy

Children, especially vulnerable to lead toxicity, can suffer a range of adverse neurological effects -- including diminished IQ -- from lead exposures once considered moderate or low. do they ever fully recover from these early exposures? Probably not, researchers suggest in the Jan. 11 NEW ENGLAND JOURNAL OF MEDICINE.

A team led by University of Pittsburgh toxicologist Herbert L. Needleman reexamined 132 young adults an average of 11 years after researchers first noted that their academic and communications abilities correlated with early lead exposures, as evidenced by deposits of the heavy metal in the subject's baby teeth (SN: 4/7/79, p. 230). Among the 10 retested individuals whose baby teeth had enough lead to signal "poisoning," half now read at a level two or more grades below the norm for their age. And among the seven who are old enough to have graduated from high school, three are dropouts.

Needleman and his colleagues divided the 122 remaining subjects into three groups: those whose baby-tooth lead levels had been low (under 10 parts per million), medium (10 to 20 ppm) or high (20 to 24 ppm). Individuals in the high-lead group proved six times more likely to drop out of school than those in the low group, even after the researchers accounted for 10 potentially confounding factors. Higher early lead levels also correlated with lower scores on vocabulary and grammatical reasoning tests, slower reaction times, poorer hand-eye coordination and lower reading scores.

"If you can still measure [lead-induced] changes in young adulthood, they're not going to go away. The brain will not repair itself, nor will the social changes that have occurred reverse," Needleman says. But the risk of lead toxicity "could be wiped out forever," he contends, if homeowners and landlords took aggressive steps to remove indoor lead -- in particular by replacing old paint and plumbing.