In Chicago, about 400,000 homes still get their tap water through lead service lines — pipes that connect individual homes to the main water line.
And nearly 70% of young children are getting exposed to lead from their home tap water, according to recent estimates published in JAMA Pediatrics. The study also finds that Black and Hispanic neighborhoods are more likely to have lead exposure, but less likely to be tested for lead.
"The concerning thing here is that [lead exposure] is happening at such a population level, and we don't know which houses have small levels of exposure and which ones have large levels," says study co-author Benjamin Huỳnh, assistant professor at the Johns Hopkins Bloomberg School of Public Health, though he notes that even low levels of lead can cause health problems.
Lead in the drinking water is still a problem in many parts of the U.S. This toxic metal has been banned from water pipes since 1986, but many homes were built before that. Lead exposure is especially high in Chicago, which has the most lead pipes out of any U.S. city, largely because the city code required the use of lead service lines until the year they were banned.
Huỳnh's estimates are based on lead detected in water samples drawn from homes. It's part of a free, voluntary testing program that the city of Chicago offers residents, but fewer than 10% of households have tested their water. "We [also] found that the people who took those tests are more likely to be in white neighborhoods, wealthier neighborhoods and also neighborhoods that are less likely to have lead in the first place," Huỳnh says.
To fill in the gaps, Huỳnh and his colleagues used a few different data sources — including demographics, health metrics and surveys on Chicagoans' main sources of drinking water. They crunched the data with the help of machine learning to predict levels of lead exposure via tap water across the city.
They estimate that about 1 in 5 children who live in homes with lead-contaminated tap water drink it as their primary source — likely leading to high levels of lead in their blood.
The results are no surprise to Elin Betanzo, president of Safe Water Engineering in Detroit. She consults with water utilities on lead, and she's analyzed Chicago's data independently.
"When it's hidden in our water and people don't have good information about lead in their water, they end up drinking it every day. That's when it really becomes a problem," Betanzo says.
Health dangers of lead
Lead is especially dangerous for young children. It can damage brains and nervous systems, cause learning and behavioral problems, and issues with hearing and speech development. In adults, lead exposure is associated with kidney damage, high blood pressure and cardiovascular problems.
And while experts say no level of lead is safe for children, cities like Chicago are still in compliance with federal laws. "The City of Chicago is working hard to ensure that Chicago's water continues to meet and exceed all standards set by the U.S. Environmental Protection Agency," the Chicago Department of Public Health wrote in a statement to NPR.
Many policymakers and safe water experts think that means the laws are too lenient. "The federal Lead and Copper Rule is a very weak regulation that does not do a good job of protecting public health," Betanzo says.
The Lead and Copper Rule — first issued by the EPA in 1991 — requires local water systems with over 15 parts per billion of lead in the water to initiate "corrosion control," adjusting the chemistry of the water so that it is less likely to leach metals from the pipes that carry it.
About 90% of cases where local water systems exceeded these limits never got reported to the federal government, according to EPA audits.
"This was probably the worst reported and enforced regulation in the history of the drinking water program," says Elizabeth Southerland, former director of the Office of Science and Technology in the Office of Water at EPA and a current member of the Environmental Protection Network.
Stricter lead limits are coming
Last fall, the Environmental Protection Agency proposed "Lead and Copper Rule Improvements," which would require most water systems to replace all their lead service lines over the next 10 years.
Under the proposed rule, however, Chicago would get an exemption because it simply has too many lead pipes. The EPA considers it "technically possible" for water systems to replace up to 10,000 lead service lines a year, which means Chicago would still be allowed to have lead pipes for the next 40 to 50 years.
"That's decades. That's generations of children and adults consuming lead contaminated water," says Chakena Perry, a senior policy advocate with the Natural Resources Defense Council based in the Chicagoland area. "It's incomprehensible to tell a resident that they need to wait that long for safe drinking water."
The EPA is expected to finalize the "Lead and Copper Rule Improvements" by late October 2024.
For Benjamin Huỳnh, the researcher at Johns Hopkins, the issue got personal a few weeks ago. He grew up in Chicago, and his parents still live there. About a month ago, a water main near his parents' home burst. Disruptions to a main pipe, and the process of repairing it, can cause lead to surge in the water. Huỳnh suspects that's why his mom had symptoms consistent with lead poisoning after drinking it.
Huỳnh helped his parents test the water — and the city called them quickly, saying they'd replace their lead pipes for free. "I know this, because I'm an expert on this. So I can tell my parents 'This isn't safe. You have to go and get this changed out,'" he says. "But this is happening all over the city."
In the short term, Huỳnh would like to see the city provide lead water filters and encourage water quality testing for everyone with a lead service line. And then get all those pipes replaced as quickly as possible.
For now, his parents are drinking bottled water.
And Huỳnh is sitting with the fact that he probably drank a lot of leaded water growing up. Still, he says, previous generations were exposed to high amounts of lead in gasoline and paint. "I think the generations before me had way more lead exposure when they were kids," he says, "It's my hope that generations after us will have even less lead exposure."
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