The Flint, MI, water crisis is already one of the greatest man-made environmental catastrophes in U.S. history, and now the Chicago Tribune has identified 200 communities in Illinois with lead levels that exceed the federal safety standards. In total, the affected public water systems service more than 800,000 Illinois residents, including many in the Chicago area.

But state officials say those shocking numbers aren’t quite as disturbing as they appear. The Chicago Tribune pored over state data and determined that 200 public water systems have had at least one lead test that exceeded the federal limits during one year or more since 2004.

in fact, some Illinois towns rely on water that regularly contains alarming levels of lead. Locally, the Tribune reports that “Berwyn and Forest View in Cook County, York Township in DuPage County, Barrington and Volo in Lake County, and Marengo and Richmond in McHenry County” also surpassed recommended safe levels of lead. Not only that, but “Testing by those water systems found more than 15 parts per billion of lead in the tap water of at least 10 percent of the homes tested, highlighting the lingering danger from lead pipes and plumbing installed during the past century.”

The Environmental Protection Agency has been criticized for its slow and reactive handling of the Flint water crisis, and now the agency is urging local communities to respond quickly to elevated levels of lead, even if it means supplying residents with bottled water indefinitely.

How Does Lead Get in Our Drinking Water?

For decades the United States has been the largest producer of chemical products in the world. The industry was valued at $770 billion in 2012, and today there are more than 84,000 chemicals on the market, many of which are largely unregulated.

In a 2010 hearing before the U.S. Senate Subcommittee on Superfund, Toxics and Environmental Health, former Senator Frank Lautenberg said that this lack of oversight turns kids into “guinea pigs in an uncontrolled experiment.”

“Everything from our cars to the cell phones we all have in our pockets are made with chemicals,” EPA Administrator Lisa Jackson said at the hearing. “A child born in America today will grow up exposed to more chemicals than any other generation in our history.”

It’s no wonder many parents have turned into “chemophobes,” who try and limit their children’s exposure to chemicals. But the dangers of lead are well known. Lead poisoning is an incurable disease that can cause developmental delays, learning problems, fatigue, hearing loss, and is associated with a higher risk of violent crime.

In the past, lead was commonly used in household paints and pipes, some of which are still in use today. That means that even if a public water system doesn’t contain lead pipes, a home’s internal plumbing could release lead into the water.

In Flint, chemicals in the water supply corroded lead pipes, releasing it into the drinking water. According to the EPA, there is no safe level of lead, and lead pipes may need to be replaced entirely.

To learn more about lead in Chicago homes, read this 2013 EPA study on Chicago’s aging water system.