Many Chicago children exposed to lead in tap water, study estimates

Researchers at Stanford Medicine and Johns Hopkins University estimate that some 129,000 children younger than 6 in Chicago have elevated levels of the neurotoxin in their blood due to lead pipes.

- By John Sanford

Children exposed to high levels of lead in drinking water can suffer learning difficulties and developmental delays.
Emily Moskal

About two-thirds of children younger than 6 years old in Chicago are exposed to lead in their drinking water, according to researchers at Stanford Medicine and the Johns Hopkins Bloomberg School of Public Health.

The researchers developed artificial-intelligence models that made citywide estimates of the number of children under 6 living in homes with lead-contaminated drinking water. They also used simulation models to estimate the increase in the children’s blood lead levels from drinking that water. The findings were extrapolated from census data and 38,385 household lead tests collected from 2016 to 2023.

“After 150 days of exposure, our models projected that the amount of lead in their blood was around twice as high as it would have been if there hadn’t been lead in the water,” said Benjamin Huynh, PhD, assistant professor of environmental health and engineering at Johns Hopkins.

Of roughly 191,000 children younger than 6 in Chicago, about 121,000 were exposed to lead-contaminated tap water, the study estimates. The researchers determined that Black and Hispanic children were more likely than white children to live in homes where the water contained lead.

A paper describing the study was published March 18 in JAMA Pediatrics. Huynh, who began the research as a postdoctoral scholar at Stanford Medicine, is the lead author. The senior author is Mathew Kiang, ScD, assistant professor of epidemiology and population health at Stanford Medicine.

The Environmental Protection Agency has determined that no amount of lead in drinking water is safe; the metal is a potent neurotoxin and increases the risk of heart and kidney disease. For young children, inhalation or ingestion of lead can cause learning difficulties and developmental delays. Children younger than 6 are especially vulnerable, according to the Centers for Disease Control and Prevention Children. Lead exposure also increases the risk of miscarriage and premature birth.

Mathew Kiang

Still, it wasn’t until 1986 that the federal government banned the installation of lead pipes in public water systems and residential plumbing. In Chicago, lead water pipes were mandated until that year, and there are still an estimated 400,000 lead service lines in place — the most of any city nationwide, the researchers say. A service line is a water pipe connecting a home or building from a municipal water line.

Incremental progress

The city government is making an effort to replace all lead service lines within its jurisdiction, but progress has been slow: Only 280 lead pipes were replaced by the city from 2020 to 2022.

The city provides free lead-testing kits, but many residents are likely unaware of the program, Huynh said. Census blocks — small geographic areas designated by the U.S. Census Bureau — with majority white populations had higher testing rates, whereas blocks with mostly Black or Hispanic populations had lower testing rates, the study said. A 10-percentage-point increase in census-block-level Black and Hispanic populations was associated with a 4% and 11% increase in lead exposure, respectively, the study said.

In November, the EPA announced a $336 million loan to help the city remove 30,000 lead water pipes. It also proposed phasing out all lead water lines nationwide within the next 10 years but gave Chicago an additional 30 years to complete the job, based on the calculation that no more than 10,000 lead service lines could be replaced there annually, Huynh said. “I think there’s a real conversation to be had in terms of what that means,” he said. “Should we really be waiting 40 years as lead continues to contaminate tap water?”

A large-scale intervention will be required to address the problem, Kiang said.

“It’s not going to get done through individual action alone,” he said. “I think the models we’ve developed could help the government prioritize neighborhoods with lots of kids who are exposed to lead-contaminated water.”

About Stanford Medicine

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