The 2016 water crisis in Flint, Michigan, was a story of failure: the failure of bureaucrats, whose malfeasance may have cost human lives; the failure of our aging infrastructure; the failure of austerity, which led to the prioritization of money over lives. And it was a failure that had enormous public-health consequences.
In 2014 through 2015, Genesee County, where Flint is located, had the nation's third-largest recorded outbreak of Legionnaire's disease, a severe form of pneumonia that people catch by inhaling microscopic droplets of water contaminated with legionella bacteria. Eighty-seven Genesee County residents fell ill; 12 of them died.
Scientists and officials are now asking whether the outbreak is indeed connected to officials' neglect of the Flint water system. Nick Lyon, the head of Michigan's health department, is facing charges of involuntary manslaughter; prosecutors say he knew about the rash of disease cases around Flint, but failed to act. Meanwhile, the state has argued that the outbreak was caused by the hospital where many people were treated. Now, a new study offers fresh evidence that the water was, for the most part, to blame.
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For the study, a team of scientists from universities in Colorado and Michigan analyzed measurements of free chlorine in the tap water in Flint and in nearby, unaffected cities, before and after Flint switched to a cheaper source of water. Because officials didn't put in proper controls to deal with the new source's more corrosive nature, lead leached from the city's pipes into people's drinking water, creating a public-health emergency that eventually captured nationwide attention. Meanwhile, scientists also think that the lack of corrosion control in Flint altered the water chemistry so that more chlorine than usual was needed to keep legionella bacteria from flourishing.
Before Flint officials switched water sources, free chlorine levels throughout the city were steady, the Colorado-Michigan team found. After, they varied wildly. At one location, they fell to lower levels for weeks on end. At another, they spiked and plunged over time. And during periods of lower chlorine levels, Flint neighborhoods were much more likely to report that a resident had contracted Legionnaire's disease, even though chlorine levels tended to be within what's typically recommended for tap water, the scientists found. For every additional unit of free chlorine a Flint neighborhood had in its water, it was 70 percent less likely to have a Legionnaire's case. Meanwhile, before the water change—as well as after officials switched back to their original source, the Detroit Water and Sewage Department, in October of 2015—Flint's Legionnaire's disease rates fell to low levels, matching those of neighboring cities.
The scientists tried controlling for cases in which people seem to have contracted Legionnaire's disease by staying in a local hospital where many Legionnaire's victims were treated. The hospital cases weren't enough to account for the close relationship between the chlorine levels in Flint residents' water and whether they caught Legionnaire's, the scientists write in their paper, published today in the Proceedings of the National Academy of Sciences. Just how many of Flint's Legionnaire's cases did officials cause with their treatment of the water? About 80 percent, the paper finds.