[otakucode]

There should be much better results than simply one single nation for that... China in particular should be extremely indicative. While the US 'banned' leaded gasoline and it took decades to actually phase out its use, China banned it and within 18 months use stopped entirely. While the US saw gradual declines, China should see a precipitous drop. It does make me wonder about places like parts of Africa which seem to have economic disparity driving violence right alongside nations which are stupendously poor (the poorest in the world) but which are very peaceful and have some of the lowest violent crime rates in the world as they lack economic disparity (everyone is similarly impoverished). Does the poor nation not use leaded gasoline or have other sources of lead? What happened in Europe with regards to leaded gasoline? Does Indonesia still use leaded gas? If looking for consequences of human nature, it's always a mistake to omit any culture.

I know that hookworm played a significantly role in the US south, and after its eradication things improved every single year since. Hookworm is still a major problem in most of Africa, though. Infection with hookworm in childhood results in permanent IQ loss, regardless of whether it is later treated, the damage remains.

My personal opinion is that we should not necessarily expect the actual monetary scale of the difference to accurately predict the magnitude of the violent crime. Most likely, the economic disparity is a proxy for something else that does not scale the same as the monetary values do. Namely control. Economic disparity always coexists with a small group exerting control upon a larger one to extract the value they create and take it for themselves. Humans always respond negatively to control - both being controlled and exerting control on others. They react pretty predictably, too. They assert control over themselves and their own bodies, then seek to establish status by being seen as dominant in their peer group, then seek to establish an alternative power hierarchy from the overaching order, then engage in plays for dominance between those alternative hierarchies (gangs), then eventually the gangs merge and become an army who goes to war against the overarching order. It happens in families, in schools, in prisons, in militaries, in nations, everywhere. Different scales, and different manifestations, but control is a poison to humans.

[emj]

The Hookworm program seems to have been more about education and sanitation than eradication, and apparently it has come back in the poorer areas of the US not quite the infections rates as earlier though. I couldn't find support for the IQ claim, but I guess it's always an issue if you are host to a parasite.

https://en.wikipedia.org/wiki/Rockefeller_Sanitary_Commissio... https://www.npr.org/sections/goatsandsoda/2017/09/12/5503876...