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Lead Levels

December 20, 2007

Even at exposures well below federal safety standards, lead can lower IQ.


Another reason to get the lead out. I’m Bob Hirshon and this is Science Update.

Even tiny amounts of lead in a child’s blood – well short of the federal safety limit – may lower his or her IQ. This according to senior researcher Richard Canfield of Cornell University’s Division of Nutritional Sciences. His team took kids whose blood lead levels all fell below the federal standard, and split them into two groups.

RICHARD CANFIELD (Cornell University):
The children who had the higher blood lead level – that is, between 5 and 10 micrograms per deciliter, had IQ scores that were about 5 points lower than the children who were in the 0 to 5 micrograms per deciliter group.

He says that’s enough to make a difference on the SAT, or to shift a kid into special education. The good news is that overall blood levels have dropped dramatically in the last few decades, which makes it possible to spot the effects of such low doses. I’m Bob Hirshon, for AAAS, the science society.