Not that I understand why they picked 23 year delay (median age of criminals?), but you'll note that crime is 2.5x higher in 2011 as 1963 but lead is less than half.
23 years was the point of strongest correlation, of course. The difference between the divorce rate and the lead is that they actually have theories for why the lead exposure leads to crime, and that the correlations hold true even when you move past the graph I showed.
They've seen that 23 year delay through varying dates for introduction, phase out, and amount of leaded gasoline used, by region.
I agree about it still being elevated, but there's a reason I said 'tied to', not 'exclusively caused by'. There's a lot of other things we need to 'fix' to get our crime down even further. Personally, I'd say 'end the war on drugs' would probably help get us down to the levels seen in the '30s. And who knows, there may be another environmental factor as bad as TEL introduced around the same time that we haven't figured out yet.
One other factor might be like tracking the number of cases of autism - you look at the numbers recorded in the '30s and today, it looks like we have orders of magnitude more of them. But today we diagnose it much quicker, and much more mild cases of it are counted. So you'd have to compare '30s 'Autism' with '00s 'Severe Autism' or such to get a better comparison. Then it'll still be elevated, just not as much (older parents is probably partly to blame).
I swear, I'm joking. Actually, I have few doubts that lead does play some role in health and/or criminality, but without significantly better proof, it's tenuous at best. While smoking gun charts are nice, with good science rarely that neat and tidy. If a report tells you what you want to hear, look very closely for the lack of rigor because it's likely junk at worst and poorly executed at best.
Like I said, the graph is neat and tidy, but there's a lot more to the actual research tying the two together.
