That smarts!

Heavy metal pollution may be costing people money in lost income – from a diminished IQ. From the AP:

WASHINGTON -- Lower IQ levels linked to mercury exposure in the womb costs the United States $8.7 billion a year in lost earnings potential, according to a study released Monday by researchers at a New York hospital.

Leonardo Tresande, a pediatrician at the Mount Sinai Center for Children's Health and the Environment, estimates that some 4% of babies born each year have blood concentrations of mercury that depress IQ by an average of 1.6 points.

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1.6 points? That's about one-tenth of the population standard deviation, and it's probably going to disappear into the standard deviation around an individual test score. How much difference can 1.6 points make?

Using work examining the effects of lead exposure on IQ, researchers determined that even a 1.6-point drop in IQ could cost a person $31,800 in lifetime earnings because of missed educational opportunities or jobs.

Oh.

And to make matters worse, the dose response to mercury is not constant over the population. Some folks are more sensitive to its effect than others. It will be interesting to see if any identifiable groups are more sensitive than others. And if it's found that's the case, it'll be interesting to see if anyone's allowed to report it.

In a related item, I heard once, in passing, a geneticist say there's a gene that makes its carrier more sensitive to the effects of lead poisoning on IQ. However, it confers some protection against malaria. Guess which demographic group has elevated levels of that gene? Unfortunately, that wanders close to the topic that got The Bell Curve on the Index of Forbidden Books.