Whether it's increased crime or lowered IQ, lead is likely not as potent as the media hype would suggest.

According to a meta study of lead vs. crime the results are inconclusive. Very high exposure to lead my cause a couple point reduction of childhood IQ, which may be temporary and not everyone exposed to lead has a reduced IQ.

Regarding lead & IQ and lead & crime ,some links to studies (and the meta study):

https://greyenlightenment.com/2021/08/02/the-effects-of-lead...

Also, the median childhood exposure to lead in the US for far back as the 1970s was around 15 ug/dl, which was the peak, which may have only conferred .5-2 pt decline in IQ

https://ourworldindata.org/exports/lead-blood-usa-children_v...

Also, this contradicted by Flynn effect, which shows IQs to be rising.