We’ve known for decades that ingesting lead is a very bad thing. It’s been linked to increased risk of dozens of disease states. The risk was so significant that lead based paint and painting have been outlawed.

NPR is reporting today about yet another study focusing on children and lead exposure.

The study followed 560 people in New Zealand beginning in the 1970’s and running through today. They tested IQ and blood lead levels when the subjects were 11 years old and again at 38.

As expected, the participants in the study who had low blood levels as children had an adult IQ that was as high as when they were kids.

However, Reuben says, children who experienced higher lead exposures “saw their intellectual abilities decline from their baseline starting point” as time wore on.

And, he adds, “people who saw that decline also experienced downward social mobility.”

This isn’t the first time lead has been linked to cognitive impairments. This study from 2011 saw similar results to the one NPR is reporting on. Further, this study found children with autism had significantly higher levels of lead (and other toxic heavy metals) in their blood.

This research is particularly troubling in the face of the continued drinking water crisis in Flint.