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.