Tuesday, March 01, 2005

Mercury, IQ, and Lost Income

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.


robin andrea said...

On March 15th the EPA will finally rule on how rigorously this toxic pollutant will be regulated. In advance of that finding, Richard Pombo (chair of the House Resources Committee) released a report titled: "Mercury in Perspective: Fact and Fiction About the Debate Over Mercury".
The report -- written not by scientists but rather by aides to Pombo and another member of his committee, Rep. Jim Gibbons, R-Nev. -- aims to downplay the overwhelming evidence that mercury from coal-burning power plants poses a significant health risk to Americans. Two of the report's claims are particularly stunning, as science journalist Chris C. Mooney points out. One: "There has been no credible evidence of harm to pregnant women or their unborn children from regular consumption of fish." And two: "Current, peer-reviewed scientific literature does not show any link between U.S. power plant emissions and mercury in fish."
Guess who helped write this report? Electric Power Research Institute and Edison Electric Institute. What's that old saying about the fox and the hen house? How do you think the EPA will rule?

JMS said...

Although there are many "fuzzy" areas when attempting to discern what affect mercury has in terms of money or productivity, I personally beat the drum whenever I can against toxic enablers.

If we're wrong about the detrimental effects (and we are not) no big deal. Prove me wrong and I go away, no children harmed.

If the government and corporations are wrong, as per usual, the human cost is high.

I have a little rant about this over at my place today...

Aquaria said...

How did I know Phila would hit on the IQ stuff after watching that flame-out from the Hi-IQ idiocy of Llortma'i last night...?

NYMary said...

I'll tell you this: when I was pregnant last year, I got a stern and detailed talk from my doctor about fish, particularly salmon, but including tuna, to which I'm pretty addicted. So the OB/GYN community, at least, doesn't think it's junk science.

Phila said...

Just to be perfectly clear, it's not the connection between mercury and developmental problems I'm questioning...quantifying a specific amount of lost earnings based on "lower IQ points" is what bothers me. Or not bothers me, but worries me. Sometimes, studies like these end up being used to discredit or cast doubt on the larger field of research.

Aquaria said...


You are dead on right about the disconnect between IQ and achievement. I joke about being dumb, but I was one of those kids who got tested--and tested--and tested--because I scored so high on the IQ test. No, it's not over 200, just high enough that the testers wanted to make sure it wasn't a fluke. After all, I was a girl. We weren't supposed to be that smart in 1967.

Anyway, with a high IQ, am I running the world? Nope. Am I even using my vaunted IQ to its maximum potential? I am ashamed to admit that the answer again is no. Dumber people than me do more and know more, for whatever reasons, but most of all because I am so lazy.