By Jared Strong, Iowa Capital Dispatch
Treated drinking water that goes to homes, businesses and schools in parts of West Des Moines contains tiny amounts of toxic, synthetic chemicals that have been linked to certain cancers.
Those contaminations were discovered in recent weeks by the Iowa Department of Natural Resources. The state agency seeks to assess the prevalence in drinking water of perfluoroalkyl and polyfluoroalkyl substances — commonly referred to as PFAS, or “forever chemicals” because they persist indefinitely in the environment.
The DNR is testing water in at least 59 cities at their sources and after treatment for human consumption. West Des Moines, the sixth-largest city in the state with a population of about 68,700, was the only city to have detectable levels of two prominent PFAS in its treated drinking water, according to early results obtained by Iowa Capital Dispatch. Des Moines’ treated water did not have them.
The chemicals have been commonly used in nonstick cookware and stain-resistant clothes and furniture. Groundwater contaminations in Iowa have been previously identified near airports, which have used firefighting foams that have the chemicals. Certain manufacturing plants and landfills are also sources of environmental contaminations.
“Overall, on a statewide basis, the risk is very low,” Roger Bruner, supervisor of the DNR’s water quality bureau, said in October before the testing.
But concerns about the chemicals have grown in recent years as researchers have shown they cause cancers and are widely distributed in the environment. The vast majority of people in the United States are believed to have detectable amounts of the chemicals in their bodies, and a recent study also found traces of the chemicals in rural creeks and rivers throughout Iowa.
Based on the recent DNR test results, at least three of West Des Moines Water Works’ groundwater wells have the two most-studied PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). It’s unclear why the wells have the chemicals, Bruner said.
“The department’s surveillance sampling program is not designed to identify source area(s),” he said.
The two chemicals were detected in concentrations of 2.9 and 2.4 parts per trillion, respectively, in West Des Moines’ treated drinking water. Their concentrations were as high as 29 and 16 parts per trillion in the wells.
That is well below the current federal health advisory levels of 70 parts per trillion for drinking water, however the U.S. Environmental Protection Agency has indicated it plans to revise the safety levels next year based on new research that suggests the safety threshold should be more restrictive. The chemicals have been shown to accumulate in people’s bodies over time.
“We’re talking about parts per trillion,” said Christina Murphy, general manager of West Des Moines Water Works. “People describe it as a drop in an Olympic-size pool. We’re talking about incredibly tiny amounts of a contaminant.”
Contaminated well shut down
Murphy said she first learned of the DNR’s test results about two weeks ago and had planned to notify water customers after the DNR published the results on its website, which Bruner expected to happen later this week.
West Des Moines Water Works shut down the well with the highest amount of PFAS contamination, Murphy said, but it’s unclear what effect that had on the treated water. There has been no further testing of that water, she said, and there are 18 other wells that were not part of the initial tests.
An investigation into the source of contamination is underway, and Water Works will test its treated water for PFAS every three months, Murphy said. There are methods to filter out the contaminants, but the water utility has no plans to implement them unless PFAS concentrations spike or federal advisory levels are significantly reduced.
“You could drink water that’s 70 parts per trillion your entire life and not see any effects from PFAS,” Murphy said, based on the EPA’s current health advisory. “We would love for water to be free of everything, but that’s not our reality. We treat water so it’s safe to drink.”
But David Cwiertny, director of the Center for Health Effects of Environmental Contamination at the University of Iowa, cautioned that further testing is needed to fully understand the scope of the problem in West Des Moines. He reviewed the data obtained by Capital Dispatch.
“This is just a snapshot,” Cwiertny said. “It’s one sample at one point in time. It only tells us that it’s there. How high can it get? How low does it get?”
Water from West Des Moines wells are treated and pumped to most of the residential areas of the city. About 30% of the city’s water is provided by Des Moines Water Works, which goes to customers south of the Raccoon River and in the far west and northwest parts of the city, Murphy said. Des Moines water is used as a supplemental source elsewhere during peak water demands in the summer.
Previous tests in 2014 did not reveal the presence of PFAS in West Des Moines water, but those tests were not as sensitive, Murphy said. Consequently, it’s difficult to say how long they have been in the water.
Shifting safety guidance
New data and analyses “indicate that negative health effects may occur at much lower levels of exposure to PFOA and PFOS than previously understood and that PFOA is a likely carcinogen,” the EPA said in November. “EPA will not wait to take action to protect the public from PFAS exposure.”
Some states have set their own more-restrictive health guidelines for PFAS contamination. In 2020, Michigan set limits of 8 and 16 parts per trillion for PFOA and PFOS in drinking water.
In July, the California Environmental Protection Agency suggested that PFOA should be limited in drinking water to .007 parts per trillion because of its risk for kidney cancer.
The EPA anticipates updating its PFAS health advisories in fall 2022. It is still assessing the toxicity of several other related chemicals that were also found in water supplies in Iowa. One of them, perfluorobutyrate, a breakdown product of PFAS, was widely detected in water sources and treated water by the recent DNR tests. But research has found its effects on people are less potent, and in 2017 the Minnesota Department of Health set a safety threshold of 7,000 parts per trillion for drinking water.
A water source for Iowa City also had detectable amounts of PFOS — at 2.4 parts per trillion in the Iowa City Sand Pit — but the chemical was not detected in the city’s treated water.