I get asked about this with some regularity, so here's the answer: Lead poisoning has nothing to do with the overall crime rate these days. Its effects lasted from the mid-60s through about 2010. After that, everyone under 30 had grown up in a low-lead environment and there was little additional improvement to be had.
The past few years have seen some peculiar ups and downs in the violent crime rate, and the murder rate in particular has increased considerably over the past year. There are lots of possible reasons for this, ranging from the statistical to the very real (George Floyd, the COVID-19 pandemic), but at the moment we don't really know the cause.
But it's not lead.
Lead likely does play a role for some individuals who commit crimes - lead poisoning is still an issue for many children, especially in older cities. But it's not going to be enough to move national statistics on crime very much.
I do wish we would talk more about the lead poisoning that still occurs. We are now stuck in the phase where reduction requires updating privately owned infrastructure. It is incredibly hard to get political movement on that type of lead mitigation, and pretty much guarantees that lead poisoning is a problem exclusive to the poorest children.
The amount of lead a child gets from living in an old apartment with some lead-based paint is minimal compared to the amount of lead that every single child used to breathe in as a result of leaded gasoline. You might think me a hideous monster who does not care about children but people who are absolutist about lead abatement are ignoring the side effects of abatement.
NYC for example has a program to remove lead from apartments that test positive for lead based paint. Now any building built before 1970 or so 100% is going to have some lead-based paint. What New York will do is come into your old turn of the century apartment, remove 100% of window and door frames and moldings and plaster and replace them all with brand new garbage. So there goes any character that your apartment used to have. Oh and they will also replace your old wooden windows with brand new white vinyl monstrosities. This is using a sledge hammer to crush a mosquito that's come to rest on a Ming vase.
I know whereof I speak here. My 1 year old niece lives in such an apartment in Brooklyn and her parents had a heated debate about whether or not to go through with this insanity. I believe they decided it was not worth it.
Sorry, this is a subject near and dear to my heart. All across the country old windows with character have been replaced by flat, ugly, white plastic garbage that will fall apart in 10 years or so, partially in the name of lead abatement. Almost no one seems to have have noticed and no one seems to care. But I do.
https://www.doh.wa.gov/YouandYourFamily/HealthyHome/Contaminants/lead/commonsources
Leaded paint is not the only source of lead poisoning.
It's because conservatives think having an anger management disorder makes them clever, any disagreement is an existential threat and they're entitled to blind obedience from all others.
Grandmother effect. Typically this refers do damage done to the cells that will eventually develop in to eggs while a woman is in the womb. I don't think lead works that way. Instead, high lead = high crime areas means families living in those areas also have to deal with the crime levels. Not to mention the damage mass incarceration does to families.
So, lead is not involved in the last N years, that has to be other, yet to be determined reasons, but for the M years prior, the answer is lead, lead, and lead.
As Kevin has pointed out repeatedly, there are underlyng causes of crime=- poverty, guns, misogyny, drugs, simple human greed and meanness= the problem is explaining the huge increase in crime that started in the 1960s and abated in the 1990s and 2000s.
No Edit function-Grrr.
When you pump gigantic quantities of a potent neurotoxin into the air, you're likely to get a lot of damaged brains and a resulting increasing in behavioral issues, crime included, caused by said poisoning.
When you're no longer doing this the effect is going to cease.
Doesn't seem all that complicated, actually.
I think spending more on childcare and education will do a lot. Also promoting the heck about birth control will help a lot.
Frickin evangelicals are demon spawn in regards to sex education and birth control.
Also Fox news is the worst.
I heard a Chicago Public Radio interview a few years ago with a psychologist focusing on mental health, family backgrounds and other factors prevalent in jail populations. (wish I remembered his name) His opinion was that fetal alcohol syndrome was associated with an astounding fraction of offenders. Other researchers play this down more saying it is a correlation to other family background issues, not causation. Check out https://pubmed.ncbi.nlm.nih.gov/19731365/
Yet I NEVER see discussed as something we can address as a society. Maybe the groupthink is "we tried prohibiting alcohol, then repealed that--don't discuss the harms, just have another drink and don't tread on that alcoholic pregnant neighbor's constitutional rights"
But the lead rate continued to decline well into the 2000s, as the graph that Drum used to post alongside these updates shows. Why is the threshold of lead quantities for detectable effects on crime drawn such that it those effects end in 2010, right when the correlation between (lagged) lead and crime breaks down? Seems like ad hoc reasoning of a classically ptolemaic sort. There was no prediction by Drum or anyone else ahead of time that the correlation between (lagged) lead and crime was going to break in 2010, they just started arguing that after the graphs started to diverge.