science

tldr:

Lead-associated mental health and personality differences were most pronounced for cohorts born from 1966 through 1986 (Generation X).

Conclusions

A significant burden of mental illness symptomatology and disadvantageous personality differences can be attributed to US children's exposure to lead over the past 75 years. Lead's potential contribution to psychiatry, medicine, and children's health may be larger than previously assumed.

The Romans managed to figure out that lead was bad for you. That didn't stop it from being used for the next 1500 years. Including in gasoline. And in paint.

https://www.epa.gov/archive/epa/aboutepa/lead-poisoning-historical-perspective.html

Up until recently, a lot of US plumbers used lead pipes in homes to bring drinking water to the faucet. Even if home lead plumbing is replaced, the pipes leading to the water meter may be lead.

https://www.epa.gov/ground-water-and-drinking-water/protect-your-tap-quick-check-lead-0

One might even say we’re leaders in our field

and an estimated 151 million excess mental disorders attributable to lead exposure.

Half of US is mentally sick?