Earlier quoted context omitted.
What has never made sense to me is that the IQ effects aren't equally visible across income/class groups, but we know there are millions of wealthy people living in old housing in Boston and NYC and Providence and so on. Lead levels in those houses must be just as high, right? But those kids aren't experiencing the same IQ effects. Surely this suggests that something else is a bigger factor?
Wealthy people are more likely to have good childcare (nannies, after school activities) where kids spend less time unsupervised and able to, for example, eat paint chips. For that matter, stuff like chipped paint is less likely to be left in a deteriorating state by more affluent owners.
Unemployed people don't need nannies, and they're the poorest. I think you're deliberately avoiding saying that poor people abuse their children, which is true. It's not much about affording anything.