Interview by Holli Cederholm
Per- and poly-fluoroalkyl substances (PFAS), or forever chemicals as they’re often referred to, are not new. And neither is the contamination of land, water, food and even human bodies by these persistent chemicals. PFAS, distinguished by incredibly strong carbon-fluorine bonds that do not easily degrade in the environment, were invented in the 1930s and were adopted by industry starting mid-century. 3M, known today for producing 60,000-plus products including adhesives, personal protective equipment and insulating materials, started mass-manufacturing PFOA (perfluorooctanoic acid) in 1947. In 1951, the chemical giant DuPont embraced PFOA in a low-friction, non-stick coating for pots and pans marketed under the trade name Teflon. A decade later, PFOA and PFOS (perfluorooctane sulfonic acid), became key ingredients in aqueous film-forming foam (AFFF), which has been used for firefighting at civilian airports and military bases around the globe.
The PFAS acronym has grown to encompass thousands of chemicals — 5,000 to 10,000, depending on who’s counting — that exist in a range of everyday items, including grease-resistant food packaging, waterproof clothing and stain-repellent furniture.
With the widespread adoption of PFAS by manufacturers across myriad industries, coupled with these chemicals’ inability to be readily broken down, it may not be surprising that over time PFAS have become a source of environmental contamination. PFAS can enter soil, water and air during both production and use of materials containing the chemicals.
Studies of occupationally exposed workers conducted in the 1970s reported PFAS in blood samples. More recent studies indicate some level of PFAS contamination worldwide, with samples confirming PFAS in the blood of humans and animals across the globe (including polar bears and beluga whales in the Arctic). PFAS have also been detected in various food products and the environment.
Exposure to some PFAS compounds, at certain levels, is linked to a range of health issues, including increased cholesterol levels, changes in liver enzymes, decreased birth weight, thyroid disease, increased risk of high blood pressure in pregnant women, and increased risk of kidney or testicular cancer. Of particular concern is that these chemicals may build up, or bioaccumulate, over time.
PFAS production — and contamination — continues today. Some of the most widely researched PFAS, including the long-chain chemicals PFOA and PFOS, are being cycled out in the United States due to known dangers (PFOA was designated to be “possibly carcinogenic” by the Environmental Protection Agency). However, these compounds are still being manufactured elsewhere and can be imported. And short-chain PFAS formulations are replacing phased-out chemicals, despite limited health research.
The issue of PFAS contamination in Maine entered public consciousness in 2016 when an Arundel-based dairy farm tested for PFAS and the results indicated incredibly high levels. Then in 2021, organic farmers in Unity, Maine, conducted private testing of well water after learning that municipal sludge was spread on the farm by a previous owner. Their results, which indicated that the water had PFAS levels 400 times more than the state’s interim drinking water standard, sent a shockwave through Maine’s agricultural community. Since then, at least 12 farms have paused sales of products in acts of radical transparency, given that there are no federal thresholds for PFAS in food at this time.
To learn more about the nature of PFAS and PFAS contamination in Maine, I interviewed Caleb Goossen, MOFGA’s organic crops and conservation specialist. The following Q&A has been edited for length and clarity.
Question: PFAS are commonly referred to as “forever chemicals.” Do PFAS really last forever? In our bodies? In the environment?
Answer: It is important to start off by saying I am sharing my current best understanding, and I am still learning more about PFAS every day. It seems that every PFAS-related question leads to more questions.
In our bodies, breakdown of PFAS compounds is very limited, if it occurs at all. The primary way most of these compounds leave our bodies is via urine, where the compounds likely re-enter the environment again as contaminants, mostly unchanged. Unfortunately, PFOA and PFOS, two specific PFAS compounds that are among the most widely recognized as human health concerns, leave our bodies at a very slow rate, which means that repeated intake of small amounts can build up in the body over time, faster than the compounds are eliminated.
To understand why decomposition rarely happens to PFAS compounds in the environment, you have to look at their signature characteristic: as defined by the Maine state legislature, they have at least one fully fluorinated carbon atom in their molecular structure. Carbon-fluorine bonds are the strongest known to organic chemistry. The bond’s strength is directly related to the amount of energy that would be required to break apart the carbon and fluorine atoms. The soil and/or water microbes that we typically rely on to decompose organic compounds into their constituent parts would need to invest so much energy into breaking those bonds that they wouldn’t get much of an energy gain from doing so — if any.
This is why remediation using bacteria and/or fungi (called bioremediation) is considered unlikely to be economically feasible on large scales. Bacteria and fungi are not likely to deliberately “attack” and breakdown PFAS molecules because of the strength of the carbon-fluorine bond, especially if they can find other organic compounds to use as energy sources. We would expect farm soil to have lots of organic molecules that would give microbes more “juice for the squeeze” in terms of energy return on investment than PFAS compounds.
Plants have been shown to take up PFAS from contaminated soil and water. However, the largest hurdle (of several) presented by phytoremediation is the question of what would be done with the now PFAS-contaminated plant tissue that would result from what would likely be many very lengthy and large-scale phytoremediation projects. The PFAS compounds are almost entirely unchanged by the plants, and the plant tissue itself could become a source of contamination.
While PFAS in our bodies, or in soil, look to be very difficult to remove, one bright spot is that many PFAS compounds can effectively be filtered from drinking water with carbon filtration and/or reverse osmosis filtration (though filtration systems need to be professionally planned and maintained for specific PFAS contamination situations).
Q: PFAS contamination of Maine farmland has been making headlines over the past several months. When and how did land and water in Maine come to be contaminated with PFAS?
A: Ultimately, all PFAS compounds are human-made, and thus synthesized by the chemical industry. From there, they either have entered commerce as a final product (e.g., aqueous film- forming foam) or gone to other manufacturing facilities to be incorporated into products (e.g., waterproof cosmetics, construction materials, ski wax, etc). There have been instances of high levels of contamination occurring at manufacturing sites where PFAS are either created or incorporated into a product. Atmospheric deposition can contaminate soils to “background levels.” PFAS compounds are all water soluble, and PFAS-contaminated water can flow anywhere the water flows, above or below ground, and bring PFAS with it. Manufacturing waste or post-consumer waste containing PFAS can end up in landfills, and has been found to escape as leachate, contaminating water.
And finally, PFAS contamination enters our own wastewater streams, either directly as PFAS-containing personal care products being washed off of our bodies and down the drain, or passing through our bodies and going down the drain as human waste. That now-contaminated wastewater ends up in septic tanks or municipal wastewater treatment systems where it may be combined with commercial and/or industrial solid and liquid wastes. Any PFAS contamination that passes through human wastewater into septic systems can then continue to move into the environment as PFAS-containing water effluent exiting the system’s leach field, or as PFAS-containing septage that is periodically removed from the tank. Similarly, municipal wastewater systems can export PFAS into the environment in the form of treated effluent water containing PFAS and in the form of PFAS-containing sewage sludge.
The contamination pathway garnering the most attention in Maine stems from the relatively recent realization that biosolids applied to agricultural land previously often contained PFAS. In some concerning instances, applications consisted of very highly contaminated biosolids which included industrial wastewater, though other concerning examples of contaminated soil arose simply from a prolonged history of sludge application. Even if the land-applied materials in question had PFAS levels below the higher end of the contamination spectrum, the recalcitrant nature of these chemicals means that they can build up in the soil over time.
Septage or sewage sludge that met Environmental Protection Agency (EPA) and Maine Department of Environmental Protection (DEP) biosolid guidelines was allowed to be applied to land in Maine as a soil conditioner and fertilizer, or may be sent to landfill disposal, before or after incineration. Since implementation, National Organic Program (NOP) rules have prohibited the use of biosolids on certified organic farms. Historically, concerns around the land application of biosolids have focused primarily on the risk potential of microbial or heavy metal contamination from the material, and EPA and Maine DEP rules have reflected those concerns. As a better understanding of the scope and scale of PFAS contamination in sludge emerged, the Maine DEP created PFAS screening thresholds, designed to prevent groundwater contamination. However, LD 1911 passed both the Maine House and Senate, and when signed by Gov. Mills, the law will prohibit all land application of biosolids derived from human waste.
Q: With the media attention, it’s easy to think that this issue is specific to Maine — and widespread amongst the state’s organic farms. Is that the case?
A: Unfortunately, PFAS contamination of soil and water occurs globally. Many locations probably “only” have background levels of contamination in soils with some localized sites of higher contamination, but the threats from contaminated drinking water sources are increasingly being recognized and may affect huge swaths of the world’s population to some degree. The extent of “in-between” levels of contamination of agricultural soils is not well known yet.
PFAS contamination from biosolids application is not widespread among Maine’s organic farms, and there’s little reason to expect organic farms to be more likely to be contaminated than any other farm. As I mentioned, the NOP rules forbid the use of biosolids in certified organic agriculture, but most of the contaminated land of greatest concern received biosolids applications before being used for organic farming — in some cases multiple landowners prior to the current stewards. NOP rules require a three-year transition period with only organic practices allowed, before land can be used to raise organic crops/animals, which is very effective in providing time for the breakdown and decomposition of most unallowed synthetic agricultural inputs. The PFAS compounds of greatest concern (i.e., PFOA and PFOS) are not intentional agricultural inputs, but instead are the result of unforeseen environmental contamination, and do not break down within many human lifespans, let alone three years of transition to organic production. It bears repeating that conventional farmers that chose to spread biosolids, did so with assurances of the practice’s safety, and never knew about, nor wanted, the PFAS contamination that came with the material. These chemicals are currently contaminating the home drinking wells of some conventional and organic farmers alike.
In many cases, current levels of farm soil contamination are likely to be some small amount lower than in prior decades because of removal through runoff, leaching and off-farm export of products. As contamination is discovered and addressed, Maine’s food system is already becoming safer in regards to PFAS. Maine is becoming the best-evaluated state for PFAS contamination risks in the country.
Q: Who should test, and how should they go about doing it? Are the recommendations and levels of perceived risk different for homeowners vs. gardeners vs. farmers? For example, is plugging an address into the septage and sludge site map enough to rule out potential contamination?
A: The Environmental and Groundwater Analysis Database (EGAD) Septage and Sludge Sites map created and hosted by Maine DEP is the best tool to begin investigating potential PFAS contamination risk, but it must be remembered what that map is and what it is not. The map only shows sites where “class B” biosolids spreading licenses were granted, when applicable records are available. Not every site on the map ended up receiving biosolids, and there may be some instances where biosolids were spread but records were not well maintained. There are a few other wrinkles; the amount of PFAS contamination at any site is going to be a product of the PFAS concentration in the biosolids that were spread and the amount of those biosolids spread there in total. Some locations have a relatively high amount of contamination from only one or two years of spreading of very highly contaminated biosolids (such as those which were combined with manufacturing waste from a facility that applied PFAS coatings), while some locations may have relatively low contamination levels from many more years of applications of biosolids that had a much lower concentration of PFAS contamination. The other big wrinkle is that only class B biosolids required a spreading license in recognition of concerns about the potential for the presence of bacterial pathogens. “Class A” biosolids were treated in some form or another (commercial composting, lime stabilization, etc.) to reduce the presence of bacterial pathogens, and their land application did not require licensing — therefore there is likely very little location data to guide us in figuring out how widely they were spread, or in what quantities.
It is very difficult to talk about testing needs in a general way, as they can vary quite a bit on a case by case basis, but for the average household the greatest health risk is likely that of contaminated drinking water. If you’re on municipal water, you can simply inquire about PFAS testing of the overall system, but for those of us on home wells self-testing is possible if done carefully to prevent sample contamination. (More information can be found on the Maine DEP’s factsheet “PFAS Sampling for Homeowners.”) A well water test that shows PFAS contamination is a good indication of potential soil contamination in the surrounding area, and you should contact the Maine DEP as soon as possible to inform their investigation as well as for information to mitigate your own exposure risk. If you get test results showing well water contamination, or have other reasons to suspect soil contamination on land you use to produce food, you may want to consider soil testing. Other reasons to suspect soil contamination on your own land would include knowledge of prior land application of biosolids or compost made from biosolids.
Q: As a follow-up, should growers who have brought in farm and garden inputs over the years be concerned about those as potential sources of contamination? I’m thinking specifically about hay and livestock feed, as well as compost and potting soil.
A: Many years of repeated applications of manure or manure-based compost from a highly contaminated farm, or from your own animals fed hay from a highly contaminated farm, may present some risk as well. At the time of this interview, the state is expected to release guidance later this year to homeowners for collecting their own soil test sample, though anyone anticipating needing more than one sample is encouraged to contact a professional to help evaluate the best path forward for efficient sampling without cross contamination.
Q: How concerned should people be about PFAS contamination of food? I’ve read that eating a diverse diet helps reduce risk, as different parts of plants, as well as different animals, concentrate PFAS differently.
A: It is difficult to generalize advice about PFAS contamination concerns, as PFAS exposure risks are variable and highly situational, and individuals’ risk tolerances will be different. Additionally, research is still ongoing. Everyone is likely to be exposed to at least some PFAS compounds everyday, from multiple sources. Two of the best studied PFAS compounds in regards to human health (PFOA and PFOS) have been found at significantly lower levels in the blood of average Americans than they were 30 years ago. Though low-level exposure to these specific compounds will likely continue for a long time because they are circulating in the world and are not easily destroyed, this is a promising sign that the phasing out of these compounds from most production in the country is helping to lower our exposure to them. There are likely to be discrete instances of higher exposures to these compounds however, including sites where sludge was land-applied in the ‘80s and ‘90s when these specific compounds were more commonly in production. The move away from PFOA and PFOS in products has not meant a move away from PFAS chemistries, however, and many manufacturers have simply switched to different PFAS compounds. Some are expected to be of lower risk, but many of these compounds have not been studied at all in regards to human health. The state of Maine has taken a precautionary approach to regulate PFAS; all PFAS compounds intentionally added to products must be declared to Maine DEP by January 2023, and new products containing PFAS cannot be sold in the state as of 2030, with exemptions to be made for unavoidable uses for health, safety or the functioning of society, which the MDEP will determine in the future. Because Maine is regulating the entire class of PFAS compounds, our PFAS exposure is expected to be greatly reduced moving beyond 2030.
In instances of discrete higher levels of contamination (industrially contaminated communities and/or areas immediately surrounding a contaminated farm), the exposure pathway of greatest concern for most people (other than fluorochemical plant workers) is thought to be drinking water. Following that is a diet that consists largely of leafy crops or livestock that is fed leafy crops (e.g., pasture, hay, whole plant corn silage) that were grown either on heavily contaminated soil or with heavily contaminated irrigation water. Another possible exposure pathway could be highly contaminated soil itself, depending upon how much an individual may be inhaling and ingesting it.
For the general population that is not living in an area with specific higher levels of contamination, having a diverse diet from a range of sources is likely going to reduce the food pathway exposure risk. Other possible pathways include food packaging, personal care products, and household dust — all of which can sometimes contain surprisingly high levels of PFAS (but also may have little or none). Children may have a higher risk of exposure due to their proximity to PFAS-containing substances (such as carpeting, dust and soil) and hand-to-mouth behavior.
Q: Farmers and other land stewards are on the frontlines of this issue. Do you have any recommendations for how to support them at this time?
A: The topic of PFAS contamination has been all-encompassing, overwhelming and exhausting for the affected farmers, land stewards and the folks who work for and with them. While most will understand consumers’ individual concerns and want to answer questions, I strongly encourage you to first seek out their websites, newsletters or social media to see any public statements or updates they have already made, which may answer your question(s).
Caleb Goossen, Ph.D., is MOFGA’s organic crop and conservation specialist. You can contact him at [email protected].