No. Low IQ is just one effect. Low impulse control is most likely cause for criminality.

Neurological and Behavioral Consequences of Childhood Lead Exposure https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689677/

>The underlying common pathway for all of these associations might be lead's adverse effects on executive functioning [19–21], resulting in poor impulse control.

Low impulse control in general seems to be one of the is the strongest predictors of criminal behaviour, whatever the cause.

sources:

http://journals.sagepub.com/doi/10.1177/0093854806292299

http://onlinelibrary.wiley.com/doi/10.1111/j.1745-9125.2000....

My understanding is that lead exposure increases impulsiveness much more than you would expect from the IQ decrease it also causes.

No.

Look at people with Down-Syndrome, they are extremely thoughtful and nice. Least likely to commit a violent act or partake in criminal activity.

there's a sweet spot, obviously if you go too low you're talking about barely autonomous people

No, but it does provide an "environmental" explanation to counter those that would like to introduce eugenics back into polite society and who point to lower IQs in poorer populations as proof of their inherent (and unfixable) inferiority.

I'm reminded of the story about how an IQ researcher spotted the telltale signs of fetal alchohol syndrome before it was named, but had put it down to the bad genes of the native tribes he was studying. It seems when you'd decided that something in inherited, it's very easy to overlook environmental causes, even when they have very noticeable impacts.

So, you're claiming that just about everything that makes us in inheritable, until things like intelligence comes into scope? Far smarter people than you or I have claimed the contrary. That's not to say environmental variables can change how IQ drifts, but there is nevertheless a large part founded on genetics.

It's not clear what you're responding to.

Lead lowers IQ (and has other negative impacts). Fetal alchohol syndrome lowers IQ (and has other negative impacts). Adding Iodine to salt apparently raised average IQ by 15 points in areas where the natural diet was low in it.

Many things are apparently very inheritable, like height, yet in certain generations almost everyone is taller than their parents due to environmental factors. This isn't exactly rocket science.

My point was that in history, the people accused of being genetically inferior (the jews, the irish, the italians, native americans, africans, chinese etc.) have generally been outgroups that have been unfairly targeted by pseudo-science, not that IQ does not have a hereditary component.

I get where you're coming from, but you can't honestly just use this as a counter-balance to genetic pseudo-science. You can't argue with genetic pseudo-science at all! You have to make your case about the foundational science first.

Lead poisoning comes with more than just an IQ drop - it increases aggression and reduces impulse control.