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Trace Levels of Lead Shown to Lower IQs

Posted by michael on from the duh dept.

constantnormal writes "This government study explains a lot of things, from the American public's propensity to elect the worst candidates, to the decreasing fraction of students who bother to study the "hard" sciences, to the overwhelming power advertising holds over their apparently simple minds. I think it was all the leaded gasoline burned in this country prior to the 1970s.
Homer Simpson IS the archetypal American -- Thinking and Reasoning is just too doggoned difficult."

1 of 78 comments (clear)

  1. Correlation != Causation by Ieshan · · Score: 5, Insightful

    The study says that lead levels are LINKED, slightly, to lower IQs. It says little about causation.

    While the researchers do say on a few occasions, correctly, that lead is a toxin which may be affecting children, it appears as if they correctly realize that their study is correlative and cannot be directly linked, therefore, to causation.

    All studies that deal with correlation cannot be linked to causation because the experimenters do not have direct control over the independant variable, nor can they tell which variable is independant in some cases. While the researchers did control for a variety of things in this experiment (The study followed 172 children in the Rochester, N.Y., area whose blood lead was assessed at 6, 12, 18, 24, 36, 48, and 60 months, and who were tested for IQ at both 3 and 5 years of age. The researchers controlled for many other factors that contribute to a child's intellectual functioning, such as birth weight, mother's intelligence, income, education, and amount of stimulation in the home)... it appears that they did not account for lead exposure by location - the first thing I might suggest.

    For instance, suppose that equal income housing varies greatly in Rochester, NY, and that certain children are growing up in worse or older neighborhoods than others? These worse neighborhoods might have a higher lead exposure than others, which might cause the subsequent decline more than the lead.

    Obviously, the children must be getting lead exposure from somewhere - have they accounted for school district (lead piping or building location of a particular school)?

    It's not that I don't believe in the study, I'd just be hesitant to scream causality.