[shas3]

The problem with the lead-crime hypothesis is that the cause of lead and the effect of increased crime are 'too far apart' with many intervening links in the causal chain, to paraphrase Steven Pinker [1]. He calls the hypothesis 'provocative, but far from proven.' The intervening links in the causal chain involve a lot of sub-causal links and hypotheses that are as yet, unproven.

[1] http://stevenpinker.com/files/pinker/files/pinker_comments_o...

[Shorel]

Even if lead can't be directly related to crime, lead poisoning causes many bad things to the human body, including learning disabilities, and reducing adult brain size in children exposed.