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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."

7 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.

    1. Re:Correlation != Causation by zenyu · · Score: 3, Insightful

      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.

      This is certainly true, but considering they also found that lead levels currently considered harmful lead to small additional IQ lowering it's pretty good evidence that we haven't found the floor where the exposure begins to have negative effects, further studies are needed at even lower exposure levels to try to find a safe level of lead in the blood. It might be lower than 1 microgram per deciliter which was this study's threshold, once we think we've found the floor we can do multiple studies to try to verify that level. I wouldn't recommend changing the EPA requirement until we really find the right level, but if I was considering a home renovation now I would certainly want to know about this study to try to avoid future cleanup costs if the marginal cost now was low enough.

      I haven't kept up with this but when I last researched this problem the EPA was only requiring water systems to bring 70% of their customers to the current clean standard. If the 70% that are safe by today's standard are actually safe with respect to the actual floor then we should move quickly to make the other 30% safe since an extra 7 IQ points for 30-40% of the population would almost certainly boost tax revenues enough to pay for the conversion (It's probably more than 30% of the children simply because parents on average can't afford the safest housing. I'm also assuming the paint problem will be solved, there are already good notification systems for homeowners and decent ones for renters at least in larger metropolitan areas.)

  2. Maybe that's because.... by tha_mink · · Score: 5, Funny

    Maybe, just maybe, only stupid people eat paint.

    --
    You'll have that sometimes...
  3. Very low levels of lead linked to IQ deficits by WolfWithoutAClause · · Score: 3, Funny

    The answer is simple. We need to make sure that everybody gets high levels of lead! They're clearly deficient in lead!

    --

    -WolfWithoutAClause

    "Gravity is only a theory, not a fact!"
  4. Wow. Nice Header by Syncdata · · Score: 3, Insightful

    This header is editorialism at it's worst. I'm sure constant doesn't have any axe to grind at all, and that this incindiery post is unintentional in every way, but nothing says "put me on your foes list" like a header that
    #1:Insults an entire Continent,
    #2:Insults said continents ability to comprehend politics/science, and
    #3:Emphatically states that said continents inahbitants are unable to refuse the siren song of Madison avenue.
    Ordinarily, I try to avoid vulgarity, trolling, and plain being offtopic, but F@!$ you too Constantnormal
    And Michael, I'm not one of these cats that criticises you all the time, but damn. In this case, you might have wanted to think this one over before posting.

    --
    "Inattention makes clowns of us all" -Bean
  5. causation already established! by js7a · · Score: 5, Informative
    ...their study is correlative and cannot be directly linked, therefore, to causation.

    No, the causation is well established.

    The correlation in question has been known since the early 1960s and confirmed repeatedly in the medical literature. Because of this, lead was removed from the ingredients of paint and gasoline in the 1970s. The causation has been confirmed since at least the publication of this 1994 meta-analysis:

    ... Lead interferes with GABAergic and dopaminergic neurotransmission. It has been shown to bind to the NMDA receptor and inhibit long-term potentiation in the hippocampal region of the brain. Moreover, experimental studies have demonstrated that blood levels of 10 micrograms/dl interfere with a broad range of cognitive function in primates. Given this support, these associations in humans should be considered causal.

    The important results from the new research cited in the article is that the threshold of activity is much lower than had previously been understood.

  6. And 125 grains of lead in the head... by vudufixit · · Score: 3, Funny

    Will reduce your IQ to zero. Quickly.