PFAS, Part 1: What are PFAS?
This is the first in a series of four (or more) articles exploring PFAS chemicals, their presence in our drinking water and soil, and implications for gardeners and foragers.
What are PFAS?
The October 3, 2021 episode of Last Week Tonight hosted by John Oliver put local PFAS contamination on my radar. I’d previously thought of PFAS (per-and polyfluoroalkyl substances) as “the Teflon chemical.” These substances are used to make products that resist grease, stains, heat, and water, and many of these products are found in American households. Examples include stain-resistant and waterproof clothing, fire-resistant furniture, food packaging, non-stick cooking surfaces, adhesives, and electrical wire insulation (CDC). They’re used in firefighting foam at military bases and airports, plus a range of industrial processes that may result in PFAS release into water or air.
As we’ll discuss in a later article, the conventional agricultural practice of spreading biosolids (composted sewage) on farm fields also exposes us to PFAS through the food and water supply.
According to the Agency for Toxic Substances and Disease Registry (ATSDR), exposure to PFAS has been linked to increased cholesterol levels, changes in liver enzymes, birth defects and infant birth weight changes, impaired immune function, increased risk of kidney and testicular cancer, increased risk of high blood pressure and preeclampsia, and more (2022).
Oliver points out that “you don’t actually have to live in a town where PFAS are dumped, or work in a factory that makes them, to be affected…PFAS last a long time, so if they sink into the groundwater or are released into the air, they can travel. And they can bioaccumulate, meaning they build up in your body over time.” The United States Environmental Protection Agency (EPA) confirms that PFAS resist decomposition and are persistent in the environment. They note that PFAS are “found in the blood of people and animals all over the world and are present at low levels in a variety of food products and in the environment. PFAS are found in water, air, fish, and soil at locations across the nation and the globe” (EPA, April 28, 2022).
Oliver puts it this way: “A CDC study has found that C8 [PFAS] is now in the blood of 99.7% of Americans. Meaning, at the very least, Vin Diesel and I finally have something in common.”
Exposure levels
Though this ATSDR resource references studies of PFAS exposure at higher levels, it’s important to note that exposure at extremely low levels can cause harmful changes in the body. In June 2022, the EPA made a major update to its Lifetime Health Advisory for PFAS exposure—from 70 parts per trillion (ppt) for PFOA and PFOS (EPA, 2016) to .004 ppt for PFOA and .02 ppt for PFOS (EPA, June 2022). These are temporary recommendations until the PFAS National Primary Drinking Water Regulation hopefully takes effect in the next few years.
In 2020, a peer-reviewed study by scientists with the Environmental Working Group (EWG) estimated that the drinking water of over 200 million Americans may contain 1 ppt PFAS or higher—over half of us (EWG). Since the EPA’s new health advisory levels are 50-250 times lower than 1 ppt, a significantly greater number of us may be exposed to unsafe levels. According to Olga Naidenko, Ph.D., who coauthored the study, “PFAS are likely detectable in all major water supplies in the U.S., almost certainly in all that use surface water” (EWG).
Photo of our vegetable garden includes beds of onions, cabbage, brussels sprouts, squash, lettuce, swiss chard, and a short bean trellis. A weeping willow is visible in the background.
PFAS Regulation
The EPA notes that there are “thousands of PFAS with potentially varying effects and toxicity levels, yet most studies focus on a limited number of better known PFAS compounds” (EPA, March 16). In other words, hundreds or thousands of PFAS substances have been used without proper safety testing. As Norah MacKendrick suggests in her book Better Safe than Sorry, US chemical regulations should be based on a precautionary principle, where chemicals are assumed to be unsafe until proven safe. Under the 1976 Toxic Substances Control Act, US regulations operate in the opposite fashion: chemicals are allowed to be used in products, industrial processes, and more without proof of their safety. Testing is only required once there is ample evidence that the chemical may be harmful—at which point, the chemical has likely been present in our homes and environment for years. The burden of the consequences is placed on the public—including the task of proving that a particular chemical is responsible for harmful effects. This is difficult to achieve when myriad variables and chemicals are at play in any body or community.
MacKendrick notes "a disturbing but familiar pattern in the U.S. retail landscape: a food or product is assumed to be safe, evidence emerges that associates it with health problems, this evidence is disputed, and the product is left on the market, leaving consumers to figure out what to do” (p. 2).
Though Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS), two of the most widely studied and utilized PFAS, have been banned in the US production, they’ve been replaced by similar chemicals. GenX chemicals have replaced PFOA, and perfluorobutane sulfonate (PFBS) is standing in for PFOS (EPA June 2022, p. 1). The EPA notes these general differences between PFOA/PFOS and these newer chemicals:
“GenX chemicals have similar persistence in the environment as longer chain PFAS, such as PFOA and PFOS. They are also more mobile than longer chain PFAS, leading to the potential to result in exposure at greater distances than legacy PFAS in off-site transport or in ground water. GenX chemicals do not appear to accumulate as much in humans as longer chain PFAS, such as PFOA and PFOS” (EPA 2021).
These newer chemicals have also been linked to health issues and/or generally haven’t been thoroughly studied. The EPA notes that “GenX chemicals have been linked to health effects on the liver, the kidney, the immune system, and developmental effects, as well as cancer. PFBS has been linked to health effects on the thyroid, reproductive system, development, and kidney” (EPA June 2022, p. 2). Though scientists have collected data on PFOA and PFOS from studies of humans who have been exposed, recommended exposure limits for GenX and PFBS are based on animal studies (p. 2)—likely because they haven’t been around long enough to generate sufficient data on effects in humans. The EPA also notes that there isn’t enough data to understand why these chemicals have these negative effects (EPA Oct 2021, p. 2).
A wooden bean trellis in our garden supports bean plants with bright red flowers.
The EPA offers these “Final Health Advisory” recommended exposure limits for GenX chemicals and PFBS:
GenX chemicals = 10 ppt
PFBS = 2,000 ppt (EPA June 2022, p. 2)
This means that the health advisory limits for these newer chemicals are hundreds of thousands of times higher than the EPA’s updated limits for PFOA and PFOS. I’m not a chemist, and I’ll direct readers to this set of EPA Fact Sheets and documents on GenX chemicals for folks who wish to learn more. It’s possible that GenX and PFBS chemicals are actually less problematic at low levels than PFOA and PFOS. However, knowing that these newer chemicals have not been adequately tested for safety, I wonder whether these advisory levels are instead indicative of the dearth of research, or the weight of corporate demand for these types of chemicals for their products and industrial processes.
The EPA also notes that these GenX exposure limits don’t take into account the possible effects of GenX chemicals and PFBS in combination with other PFAS (EPA 2021), which is likely widespread. Setting recommended safety levels of GenX chemicals without this data is inevitably a shot in the dark.
It’s important to note that EPA health advisories are “nonenforceable and non-regulatory” (EPA June 2022, p. 1). Rather than influencing companies to change their production practices and applying pressure to use safer chemicals, these advisories are intended to “provide technical information to states agencies and other public health officials on health effects, analytical methods, and treatment technologies associated with drinking water contamination” (p. 1). In other words, these advisories help communities understand that PFAS exposure is occurring and is a problem so we can attempt to remediate the contamination ourselves.
The EPA intends to publish a National Drinking Water Regulation for PFOA and PFOS by the end of 2022, and they expect a final ruling on this regulation by the end of 2023. You can learn more and stay up to date here.
……
After watching the Last Week Tonight segment on PFAS, I clicked over to the Environmental Working Group’s (EWG) PFAS Contamination in the US map referenced in the show. The map pins two PFAS contamination sites in western NY. One is in the Niagara Falls area, and the other is in Gerry—the town I live in. I was surprised to find that the Gerry site is right around the corner from my home—less than two miles away.
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Sources:
Agency for Toxic Substances and Disease Registry. “What are the Health Effects of PFAS?” Webpage. Updated July 5, 2022.
Centers for Disease Control. “Per- and Polyfluorinated Substances (PFAS) Factsheet.” Webpage. Last reviewed May 2, 2022.
Environmental Working Group (EWG). “Study: More Than 200 Million Americans Could Have Toxic PFAS in Their Drinking Water.” October 14, 2020. Webpage.
Last Week Tonight, Season 8, Episode 25. October 3, 2021. View episode. Transcript.
MacKendrick, Norah. Better Safe than Sorry. University of California Press, 2018. p. 2.
US Environmental Protection Agency (EPA). “Fact Sheet: Drinking Water Health Advisories for PFAS: Fact Sheet for Communities.” June 2022. Webpage.
US Environmental Protection Agency (EPA). “Fact Sheet: PFOA and PFOS Drinking Water Health Advisories.” November 2016. Webpage.
US Environmental Protection Agency (EPA). “Human Health Toxicity Assessments for GenX Chemicals.” Webpage. Updated January 13, 2022.
US Environmental Protection Agency (EPA). “Our Current Understanding of the Human Health and Environmental Risks of PFAS.” Webpage. Updated March 16, 2022.
US Environmental Protection Agency (EPA). “Per- and Polyfluoroalkyl Substances (PFAS).” Webpage. Updated June 16, 2022.
US Environmental Protection Agency (EPA). “PFAS Explained.” Webpage. Updated April 28, 2022.
US Environmental Protection Agency (EPA). “Technical Fact Sheet: Human Health Toxicity Assessment for GenX Chemicals.” October 2021. Webpage.
