A new study attempts to put a dollar amount on lost earnings due to childhood mercury intake:
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.I have mixed emotions about studies like this one. Their assumptions tend to be open to considerable dispute, and in some cases they end up coming across as "junk science" even when their methodology is basically sound, simply because they're not written in a way that reduces the chance of propagandistic misuse by one side or the other.
As regards these specific findings, I'm extremely wary of studies that link future productivity, earnings, or social status to IQ. The scientist chosen to debunk the findings shares at least some of my concerns:
Leonard Levin, a scientist at the Electric Power Research Institute, said no group has produced hard evidence to back up the estimates of the impact mercury has on intelligence.It's also true that no one's produced hard evidence that IQ and "intelligence" have any meaningful correspondence, or that IQ has a broad predictive value that reliably cuts across socioeconomic lines. That gratifying point of agreement aside, the article might've mentioned the Electric Power Research Institute's massive conflict of interest, since it's a front group for mercury-spewing energy companies, and has a history of conducting scientifically questionable studies itself.
That said, if science knows anything at all, it knows that mercury is a neurodevelopmental toxin, and that relatively small amounts of it will affect infant brains to a greater or lesser extent. I have no doubt that there's a social cost associated with childhood mercury exposure, and I suspect that it's shamefully high; whether or not it's really quantifiable is another matter. Still, I think this type of research is useful; it's far more reasonable to debate the amount of damage that environmental toxins do, than to argue over whether or not the damage occurs.
UPDATE: Chris Mooney has written an excellent article on Republican attempts to downplay the dangers of mercury, which - needless to say - rely heavily on skewed data from industry groups like EPRI.