In a new study timed coincidentally(?) to the release of an EPA report titled Environmental Health Threats to Children, prenatal exposure to polychlorinated biphenyls (PCBs) was linked to a 6.2-point reduction in IQ.
Researchers examined 167 children of mothers who had eaten at least 25 pounds of Lake Michigan fish over the preceding six years. Umbilical-cord samples were analyzed for PCBs, lead, mercury, DDT and other organic pesticides, and compared to the children's IQ scores at 11 years of age.
That was the story--but not the WHOLE story.
First, and as acknowledged by the researchers, [t]he [biological] mechanism responsible for this heightened intrauterine vulnerability is not known. Which means that their conclusion is just a naked assertion based only on statistical comparison.
The fact that no biological mechanism is known is particularly important given that no reduction in IQ was associated with mercury, DDT or the other organic pesticides tested. Thus, the PCB association could have resulted from data dredging. (If you look for enough associations, just by chance, you're bound to find something!)
Second, the researchers stated that [t]here was no evidence of gross intellectual impairment among the children we studied. I'm not aware of the IQ test being the ultimate, indisputable, and definitive measure of intelligence. Particularly when the difference at stake is only about 6 points.
What really gets my dander up is the blatant politics of this study.
An earlier version of the study was discussed in Our Stolen Future. And this seems to be a rehash of that similarly flawed version impeccably timed (September 12, 1996) with the release of the new EPA report (September 11, 1996). And if you think this was a coincidence, have I got some swamp land for you!
One of the main conclusions in the EPA report is [c]hildren whose mothers have high levels of PCBs when pregnant may develop learning disabilities and experience delayed development. The Jacobsons are the only "scientists" [junk, that is] who have reported this "phenomenon."
Moreover, the EPA reported is filled with lots of "apolitical" statements like [p]rotecting our children is one of the Clinton Administration's highest priorities and [t]he Clinton Administration has acted to protect children from environmental risks.
Like the rest of us are anti-children. Hey, I'm a former child myself! Click here to see what I think is a greater risk to children.
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