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Childhood lead exposure linked to lower IQ in adults across socioeconomic status

Mar 28, 2017

Switching Flint to water from the Flint River had devastating effects for residents, particularly its children. 

Dr. Mona Hanna-Attisha first sounded that alarm in the summer of 2015. Her tests proved that after Flint switched the source of its drinking water, blood lead levels in Flint kids skyrocketed.

And that was later confirmed by a CDC analysis. It found that children who drank Flint water had a 50% higher risk of dangerously elevated blood lead levels than before the switch.

That analysis couldn't say exactly how many kids were affected, or what their futures hold.

A study published today in the Journal of the American Medical Association may hold some answers. Researchers from Duke University studied childhood lead exposure and adult outcomes.

Aaron Reuben, a doctoral student in clinical neuropsychology at Duke, is the principal investigator and author of the study, which started more than 40 years ago in New Zealand. Reuben joined Stateside to explain the study's findings. 

But first, why New Zealand?

According to Reuben, New Zealand had some of the highest lead and gasoline levels of anywhere in the world. That meant a small town of about 150,000 people in the South Island had higher-than-expected lead exposure levels. Most of the exposure was due to exhaust from car tailpipes. 

Adults exposed to this high level of lead as children had lower IQ and often took a step down the socioeconomic ladder (relative to their parents), the study found.

Subjects were compared with peers, with each other and with themselves. The study was able to examine each child before and after lead exposure. 

Among the study's subjects, lead exposure was not higher among people who started out lower on the socioeconomic ladder.

"That was the unique thing about this group of people," Reuben said. "In most places, we know lead burden tends to be borne a lot more by lower income communities. Partly when lead was in gasoline, that was people who lived near busy roads, highways, but also people who lived near lead-emitting industrial sites and also people in older homes with lead paint and lead pipes."

Reuben said the way the city in New Zealand was designed, there weren't very many big roads and neighborhoods were, for the most part, equally dense. While there was some variation in lead exposure, research showed it wasn't based on socio-economic status.

Listen to the full interview above to learn why Reuben said there is great need for long-term funding and support for populations exposed to lead.

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