Federal Health Study on Drinking Water Contaminants Calls Into Question Safety of Nation’s Drinking Water Supply
By Laurel Schaider, Union of Concerned Scientists
On a late June evening in a high school auditorium in Exeter, NH, dozens of people stepped up to the microphone to tell EPA about contaminated drinking water in their communities. They described unexplained illnesses in their families, expressed frustration about inadequate government response, and shared their guilt and fear about their children’s exposures to toxics and the possible long-term effects. “Years before becoming pregnant, I was educating people on how to eliminate environmental toxics from their personal care products and food. That’s why this was so devastating,” said Alayna Davis, co-founder of a local community group called Testing for Pease. “I could not prevent this water from contaminating my son’s body.”
This event was the first in a series of community listening sessions that EPA will host nationwide on a class of chemicals called PFASs, or per- and polyfluoroalkyl substances—toxic chemicals that, in recent years, have been detected in drinking water supplies across the country serving millions of Americans. A new federal report on PFAS health effects suggests that drinking water guidelines developed by EPA are not protective enough and should be lower. Scientists, environmental organizations, and community groups are urging the agency to take strong steps to address the problem. How the agency will respond is unclear at this point. What we do know, however, is that regardless of EPA action, the problem will not go away anytime soon unless we reduce our reliance on these chemicals and invest in safer alternatives.
A wake-up call
PFASs are ubiquitous. They’re used in stain-repellent furniture and carpets, waterproof clothing, nonstick cookware, and even some fast food packaging and dental floss. They can also end up in drinking water through waste released from chemical manufacturing sites as well as military bases and airports where PFAS-containing firefighting foams have been used. Due to their extreme persistence, these chemicals have been dubbed “forever chemicals.” PFASs are found in all of our bodies, and have been linked to cancers, developmental and reproductive toxicity, thyroid disease, immune system toxicity, and other effects.
In May, there was public outcry over efforts by the White House and EPA to delay the release of a federal health study on PFASs. The study was conducted by the Agency for Toxic Substances and Disease Registry (ATSDR), part of the U.S. Centers for Disease Control and Prevention (CDC). According to internal EPA emails obtained by the Union of Concerned Scientists, officials were looking to avoid a “public relations nightmare.” Advocacy groups circulated online petitions and launched social media campaigns, pressing the government to release the report. On June 20, after much anticipation and controversy, ATSDR finally released a draft of the study, which found health risks associated with exposure to PFASs at levels much lower than the threshold levels estimated by EPA.
Weighing the evidence
Weighing in at 852 pages, the report is a comprehensive review of dozens of published studies on the toxicity of PFASs in humans and laboratory animals. While there are at least 4,700 PFASs on the global market, the report looked at just 14 types—ones the CDC monitors in the general population. Of these, ATSDR found it only had enough information on four—PFOA, PFOS, PFHxS, and PFNA—to generate what are called minimal risk levels, or MRLs.
An MRL is essentially a measure of how much of a chemical a person can be exposed to each day without it causing health effects. MRLs encompass exposures from all sources, including drinking water, food, and consumer products. To calculate an MRL, scientists identify the lowest levels of exposure shown to cause harmful effects in humans or laboratory animals. They further reduce these levels by building in various safety factors to ensure that MRLs are protective for even the most vulnerable populations, such as pregnant women and children.
Safety in numbers
What got the attention of EPA officials earlier this year was that ATSDR’s new MRLs for PFOA and PFOS (the two most prevalent PFASs) are 6.7 and 10 times lower, respectively, than comparable values developed by EPA, which are known as reference doses (RfDs).
Although MRLs and RfDs are more or less the same thing, in this case, there were some differences in the way the two agencies generated their numbers. For PFOS, ATSDR and EPA both based their values on the same study that showed developmental effects in rats. However, in calculating its MRL, ATSDR lowered its value by a factor of 10 to account for additional studies showing effects on the immune system at low levels of exposure. In the case of PFOA, ATSDR and EPA relied on different studies altogether for their calculations.
What does this mean for our drinking water?
In May 2016, EPA issued a non-enforceable drinking water health advisory of 70 parts per trillion (ppt) for PFOA and PFOS, individually or combined. Dozens of public water supplies across the U.S. scrambled to meet this new advisory by shutting off polluted water sources and installing new treatment. For instance, on Cape Cod, where I have been studying unregulated drinking water contaminants including PFASs since 2010, the Hyannis Water System issued a temporary do-not-drink advisory to its customers. It has since spent millions of dollars to install large carbon filters to remove PFOS and PFOA from polluted wells.
The EPA develops its drinking water health advisories based on its RfDs, and includes assumptions about how much water people drink and how much of people’s exposure comes from other sources. Using the same methods and assumptions as EPA, when we translate ATSDR’s MRLs into drinking water guidelines, we get equivalent levels in drinking water of 7 ppt for PFOS and 11 ppt for PFOA—7 to 10 times lower than EPA’s. These values are also similar to those developed by New Jersey’s Drinking Water Quality Institute, which recommends limits of 13 ppt for PFOS and 14 ppt for PFOA.
What’s next?
The public comment period for ATSDR’s report ends on August 20, and anyone can submit comments online. Meanwhile, back in New Hampshire, officials from EPA’s Washington DC and Boston offices have pledged to take action on PFASs in drinking water. Following a federal PFAS summit in May, EPA identified four areas for future action, including developing enforceable drinking water standards and groundwater cleanup recommendations to speed up remediation at contaminated sites.
These are good first steps. EPA should also consider ATSDR’s recent report and additional evidence of health effects at low levels of exposure. For instance, a study led by Harvard researcher Philippe Grandjean concluded that drinking water guidelines for PFOS and PFOA should be closer to 1 ppt based on immune system effects in children. In addition, studies in laboratory animals have found that low levels of PFOA exposure can impair mammary gland development. This is concerning because research shows that altered mammary gland development may increase breast cancer susceptibility later in life.
While PFOS and PFOA have received the most attention, it’s important to remember that PFASs are a broad group of chemicals, each with its own unique structure but united in their persistence. Although manufacturers have moved away from PFOS and PFOA, new alternative PFASs have emerged to fill their place, and these too raise concerns about effects in the environment and in people. Efforts to limit PFASs as a class rather than one at a time, such as Washington State’s recent ban on PFASs in food packaging and firefighting foam, are an important step in the right direction. Residents of affected communities across the U.S. are demanding action, and EPA needs to follow up on its promises by taking strong steps to protect public health.