Drinking water that is drawn from the Mississippi River by three Iowa cities has toxic chemicals that persist indefinitely in the environment, according to test results released this week by the Iowa Department of Natural Resources.
Burlington, Davenport and Keokuk drinking water that goes to a combined total of more than 183,000 residents contains trace amounts of perfluoroalkyl and polyfluoroalkyl substances — commonly known as PFAS or “forever chemicals.”
The DNR tests of the water are part of the department’s survey of dozens of community water supplies across the state in recent months. Previously published tests found PFAS in Ames, Sioux City, Rock Valley and West Des Moines water.
The new data also show the presence of PFAS in other Mississippi River towns of Camanche and Muscatine, but they draw water from wells.
The tests revealed combined concentrations of two prominent PFAS — perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) — of fewer than 10 parts per trillion, which is well below the current federal safety threshold of 70 parts per trillion. However, it was the first time the DNR tests found the chemicals in notable concentrations in a major river, where large amounts of water can hide contaminations.
“There’s a huge dilution factor,” said Shane Johnson, general manager of Burlington Municipal Waterworks.
Tests of Burlington water found combined PFAS concentrations of 6.5 parts per trillion in the raw water that is drawn from the Mississippi and slightly higher concentrations of 7.2 parts per trillion in its treated water. The city will test its water every three months to monitor the contaminant levels.
The precise sources of contamination are unclear because the river drains such a large area upstream, including parts of Illinois, Minnesota and Wisconsin.
“You don’t know what’s above you,” Johnson said. “You don’t know who’s dumping what in there.”
In 2018, the state of Minnesota reached an $850 million settlement with 3M Company — a major manufacturer of the chemicals that have been used to make non-stick and stain-resistant coatings for a variety of household items. The case involved the contamination of about 150 square miles of groundwater near the Mississippi and one of its tributaries, according to the Minneapolis Star Tribune.
No other tests of municipal water supplies in Iowa along the river were planned as part of the DNR’s recent survey, said Corey McCoid, a supervisor of the DNR’s Water Supply Operations Section. He said the tests are not meant to determine sources of contamination, but that upstream industrial facilities and wastewater plants are likely contributors.
McCoid said tests of Illinois cities along the Mississippi have yielded similar results.
David Cwiertny, director of the Center for Health Effects of Environmental Contamination at the University of Iowa, reviewed Iowa’s results and was troubled by the consistency of the contamination of a large river, as measured in cities that are many miles apart.
“This suggests that the Mississippi River, at least along the 100-mile plus stretch between Davenport down to Keokuk, contains a mixture of PFAS chemicals, and any other community in that area using the Mississippi as a water supply could be vulnerable to PFAS exposure,” Cwiertny said. “Given the size of the Mississippi River, at those concentrations, we are talking on the order of kilograms of PFAS chemicals per day being discharged down the Mississippi.”
He said the test results further illustrate the pervasiveness of PFAS in the environment. Researchers have been unable to determine how long it takes the chemicals to degrade naturally, and they have a tendency to accumulate in people’s bodies. Research has shown the chemicals can cause cancers and other ailments when ingested by people.
The U.S. Centers for Disease Control and Prevention has found that the vast majority of Americans have detectable amounts of PFAS in their blood.
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