We’ve known for decades that high blood lead levels can lead to lasting learning disabilities and physical health issues.
But now, a new study indicates that even the slightest change of lead in the bloodstream can dramatically impact a child’s educational outcome.
Researchers examined whether housing remediation programs in Rhode Island that removed lead from the home could reduce children's blood lead levels and improve their performances on standardized tests. They were particularly interested in examining the effectiveness of the remediation programs, as the way in which individual homes were targeted varied and implementation statewide operated on a number of different timelines.
Their findings suggested small changes in lead exposure could have significant effects in both directions. Kids who had just a small increase of lead in their bloodstream (just one microgram, so jumping from 3.1 µg/dL to 4.1 µg/dL, for example), also had reading comprehension skills fall by an entire point.
Similarly, a child’s math skills were negatively impacted as well — the study found the probability of a child lacking proficiency in math increased by 2.1 percentage points.
But for kids whose blood lead levels decreased by a microgram, the study found they performed better on standardized tests and the likelihood of being deficient in reading and math fell.
In other words: A slight increase of lead in blood widens the education gap, but a slight decrease narrows it.
Anna Aizer, one of the study’s authors, has been researching lead exposure for years. In a conversation we had back in February, she told me that disadvantaged children are much more likely to live in older housing and have a higher exposure to lead, which is why comparing the educational outcomes of children with high and low levels of lead in the blood is complicated.
“You can’t just compare the educational outcomes of high and low lead levels,” said Aizer. “It’s complicated to parse out the effect of poverty or race on test scores, but controlling for that, we found that lead still impacts test scores, particularly in the bottom distribution of test scores.”