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I have posted this before on HN, but I don't understand how, as lead levels continued to rise, IQs also increased during the 20th century. And someone pointed o

by ern 12y ago

I have posted this before on HN, but I don't understand how, as lead levels continued to rise, IQs also increased during the 20th century. And someone pointed out in another comment, as blood lead levels have plunged, we should have seen the lost IQ points being recovered. Has there been evidence of a large gain in IQ since blood-lead-levels have dropped?

Terr_ 12y ago
That presupposes that trace lead exposure (as opposed to larger doses) measurably harms IQ as opposed rather than manifesting in other kinds of neural/behavioral issues.
- ern 12y ago
  That is true-the lead-crime link seems compelling. But I've been browsing a fair amount on the subject, and the lead-IQ link is always quite heavily featured. Some studies claim differences of 5 IQ points between children with blood lead levels between 5 and 10 micrograms per deciliter. Since blood lead levels are far lower than 5 for the majority of children nowadays, and much lower than they were when we were kids, these IQ differences should be clearly apparent between generations.