No safe level of lead, study suggests
Even low exposure to metal
in paint may impact child IQ
WITH a lead concentration of less than 10 micrograms per deciliter
of blood scored an average of 11.1 points lower than the mean
on the Stanford-Binet IQ test, the researchers found. The mean
is the intermediate value between the lowest and highest scores.
Children are most commonly exposed to lead by inhaling lead-paint dust or eating paint flakes. Lead-based paint was widely used in homes throughout the 1950s and 1960s until it was banned in 1978.
At high levels, lead can cause
kidney damage, seizures, coma and death.
The study also found an average 5.5-point decline in IQ for every additional 10-microgram increase in blood-lead concentration, said Lanphear, a physician at Childrens Hospital Medical Center in Cincinnati.
The study adjusted for other predictors of lowered IQ such as the mothers IQ, tobacco exposure and intellectual environment in the home, Lanphear said.
Lanphears findings confirm
what those who work with lead kids already know,
said Ruth Ann Norton, executive director of the Baltimore-based
Coalition to End Childhood Lead Poisoning.
Besides affecting reading and
reasoning abilities, lead also is linked to hearing loss, speech
delay, balance difficulties and violent tendencies, Norton said.
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