Trace Levels of Lead Shown to Lower IQs

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."

Comments

causation already established!

[js7a]

...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.

Re:Bell Curve

[Henry V .009]

One of the most common errors made when discussing this sort of thing is to imagine that there are only two races, the 'White' race, and the 'Black' race. It is particularly common amoung white educated liberals, the supposed 'tolerant class', for some reason. And you -- no doubt innocently -- assume that even if there were other races, they couldn't score higher than whites. That's an interesting subconcious expresion on your part, but we don't really need to discuss it. The Asian average is around 15 points higher than the White average. Moreover certain groups (Ashkenazi Jews, high-caste Indians) score even higher as a population.

Of course, the 100 mark wasn't set that exactly, so all that is important is to understand that a clear relative difference appears wherever the mean is.

IQ tests are never racist. Only people are.

Well, it is possible to make manifestly racist tests. For example, you could predicate voting rights in the American southwest on English ability. Tests like that have been used around the world for many reasons. I agree with you that IQ tests are not amoung these.