It's only 3 IQ points, 1/5 of a standard deviation so not really massive. Of course there are much bigger effects on IQ such as the factors that cause low income children, and people in poor countries to have low IQs which swamp the lead effect.

I imagine frequency and budget of renovations in older housing influences the degree of lead exposure from paint. Poorer neighborhoods may have housing units with largely original (or old enough to contain lead) paint, whereas richer neighborhoods would have a larger proportion of high quality renovations which would eliminate some of the lead paint

If you have money, and it’s your house then you get the old paint stripped when you repaint. If you are buying a home, and there is lead paint, then you negotiate down on the price to compensate for removal.

Landlords of shitty apartments or houses just slap a new coat of the cheapest possible paint over the old.

99.99% of the time there is zero cost reduction due to the presence of lead paint in a normally maintained home. All old homes have it or are assumed to have it.

Stripping is uncommon and can't remove all lead paint from porous surfaces anyway -- like concrete blocks, walls, or ledges.

Landlords use a special lead blocker paint if required to pass inspections. Otherwise -- who knows.

That doesn’t explain it though because lead paint covered by regular paint is quite safe unless your children eat chunks of the wall (quite possible).

Eating chunks of intact wall is unlikely, but surfaces like window sills are very risky because they constantly flake. That’s the nuance of lead mitigation. You can be completely compliant and safe for children with some lead paint on intact walls.

Any tenant can force their landlord to remove lead in those high risk areas (at landlords expense!) if there’s a young child but few renters know about this option.

Not true. Abatement is required. That is not the same as removal. Lead blocker paint or otherwise taking the surface out of contact is usual solution.

I don’t see what was untrue. Abatement still leaves lead paint on the walls. It’s a misconception that lead compliance means “no lead in house”.

Most realtors in Boston don’t bring up lead. There’s a big culture of don’t ask don’t tell.

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.

Just as a matter of common sense and gut-check plausibility, what are we talking about when we talk about "eating paint chips?" Does eating a couple flakes lower your IQ in a measurable way? Seems very unlikely. What are we talking about, then? Do we imagine kids to be shoveling paint chips into their mouth day after day? Surely that's a pretty small number of children (if it's any), nowhere near enough to suggest generational, cohort-level effects. So what is it that we really think is happening here?

My personal experience as a landlord: kids putting their mouths on rails and banisters that are at the level of their mouths. Vivid memories of kids standing around just hanging out on the deck (pre-Internet obviously) with their mouth on the rail. "Does eating a couple flakes lower your IQ in a measurable way? Seems very unlikely." Like asking about the effect of a little second-hand smoke. Probably not a measurable effect, but many people would not be consoled by the inability of the data to register an effect.

It's not just chips, but also dust. Regardless, it has enough effect for the CDC to have a page about it:

https://www.cdc.gov/nceh/lead/prevention/sources/paint.htm

The study in the OP also specifically calls it out:

>Our estimates, based on leaded gasoline consumption, may also have underpredicted high-lead exposures owing to leaded paints and pipes, which tend to aggregate within particular communities (e.g., those with high rates of homes with lead service lines and lead paint in disrepair).

It's from dust on surfaces, toys, and hand to mouth. All toddlers should be tested. There is no surety! Any soils or dust could be contaminated from the heyday of leaded gasoline and paint.

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.

That's because there's this quite "sticky" situation of not every human being being the same. Nobody likes to talk about it and you get shunned or imprisoned for even thinking about it, but the world has actually groups of people with varying levels of intelligence.