MSU Extension Agriculture

What are PFAS?

Per- and polyfluoroalkyl substances (PFAS) are a group of human-made chemicals that were designed to repel oil and water, for temperature resistance and friction reduction for a plethora of consumer and industrial products. Some examples of these products include coatings for various textiles, paper products and cookware, along with use in firefighting foams and insecticides. Chemicals in the PFAS family were created in the 1940s and may now include between 5,000 to 10,000 different chemical structures. Two of the most commonly recognized and concerning PFAS are perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), which were voluntarily phased out of production starting in the early 2000s.  

Due to the strength of the chemical bonds between fluorine and carbon in these chemicals, PFAS have an extremely long half-life, hence the name “forever chemicals”. Destruction of PFAS chemicals requires combustion at extreme temperatures ranging from 1,472 to 2,012  degrees Farenheit. Because PFAS do not breakdown easily, they accumulate in the environment (i.e., air vapor and particulates, soil, water/rain, plants, animals, and humans; Figure 1). Thus, the food supply is one of many ways that can spread PFAS to humans. The Centers for Disease Control and Prevention National Health and Nutrition Examination Survey reported that PFAS has been found in 98% of human blood serum samples collected, while the PFAS levels have been declining since 1999 (Figure 2). More recently, negative human health impacts including liver cancer, increased cholesterol, and thyroid disease have been associated with PFAS. Ongoing research is continuing to monitor human populations in locations contaminated with high levels of PFAS to determine the subsequent health effects. The U.S. Food and Drug Administration (FDA)  and Michigan State University Extension PFAS contamination response website have more information on PFAS.

PFAS in Michigan

An interactive map of PFAS sites in the state of Michigan shows that it is the leading state in recognized PFAS contamination sites as shown in this interactive map of the United States. This may be influenced by the amount of PFAS testing that has occurred in those locations to monitor and gain a better understanding of PFAS contamination within the state. To combat the ongoing concerns with PFAS contamination, the Michigan PFAS Action Response Team (MPART) was created with members from seven agencies (Michigan Department of Environment, Great Lakes, and Energy (EGLE); Michigan Department of Health and Human Services (MDHHS); Michigan Department of Agriculture and Rural Development (MDARD); Michigan Department of Natural Resources; Michigan Department of Transportation; Michigan Department of Licensing and Regulatory Affairs; and Michigan Department of Military and Veterans Affairs). The Michigan State University Center for PFAS Research has been established to quantify and communicate PFAS risks, and mitigate their impacts on human health, agriculture and natural resources in a collaborative effort with MPART.

PFAS and cattle

In January of 2022, as the result of an MPART investigation into the contamination of municipal wastewater biosolids (sludge) with PFAS, MDHHS and MDARD issued a consumption advisory regarding beef from a Livingston County beef farm. The beef was found to contain 1.9 parts per billion (ppb) PFOS, which is less than the level that warrants a recall from the U.S. Department of Agriculture (USDA). This is an unfortunate and emotional occurrence for the Livingston County beef farmer who has experienced business disruption because he was unaware of the contaminated status of the municipal wastewater biosolids that were applied to his crop fields. Municipal wastewater biosolids are often applied to crop fields as a source of fertilizer. Due to the application of municipal wastewater biosolids contaminated with PFAS, the crops (e.g., sorghum, haylage, and corn silage) produced for livestock feed also became contaminated with PFAS. The consumption of the PFAS contaminated feed then exposed the beef cattle to relatively high levels of PFAS. In 2021, EGLE began requiring PFAS testing and restricting municipal wastewater biosolids land application with PFOS levels greater than 150 ppb to mitigate futures issues from arising.

Reporting of dairy and beef cattle farms impacted by the contamination of PFAS from other states have been found from PFAS containing products and municipal wastewater biosolid application to crop fields. If you suspect your soil, water, feed, or cattle products (i.e., beef or milk) to be contaminated with PFAS you can submit and pay for sample testing. Laboratories that provide PFAS testing can be found on the EGLE “PFAS Drinking Water Rules” website.

Research conducted by USDA Food Safety and Inspection Service (FSIS) with two different PFAS (PFOA and PFOS) in beef cattle demonstrated different absorption and excretion rates. When administered a large one-time dose (1.0 mg/kg body weight) of PFOA, it was absorbed rapidly and excreted primarily in the urine within nine days by the Angus steers used for this study. However, PFOS behaves differently in the body of cattle and when given a large one-time dose (8.0 mg/kg body weight) of PFOS, it was primarily stored in the blood plasma, liver, bile and kidney of Angus steers and excreted in the feces. Interestingly, PFOS redistributes itself multiple times and binds differently in the body of cattle before eventually being excreted. The estimated half-life, or time necessary to reduce to half of the initial value, of PFOS in the blood plasma was 116 days. A follow-up study with Angus steers given a small one-time dose and heifers given a large one-time dose agreed with cattle having blood plasma half-lives of 120 and 106 days. The half-life of PFOS in other tissues was 385 days for the kidney, 165 days for various muscles, 116 days for the liver, 141 days for bone, and 36 to 41 days for fat from Angus steers and heifers.

In another study conducted in Australia, Belted Galloway heifers and cows had previously consumed water contaminated with various PFAS (PFOS = 30 μg/L or ppb). The resulting blood serum half-life of PFOS was 76 days, which is much less than the FSIS studies that administered a much larger one-time dose. The half-lives of other tissues were also less for the liver (116 days), kidney (87 days), and muscle (77 days). The reasoning for the differences between the different experiments is uncertain but could be due to differences in PFAS dosing concentration and time exposed to PFAS. Therefore, these factors may impact the excretion rate of PFAS in cattle.

Current regulations regarding PFAS

In June 2022, the Environmental Protection Agency set interim drinking water health advisories of 0.004 parts per trillion (ppt) for PFOA and of 0.02 ppt for PFOS. However, the current quantification level to ensure reliable and consistent laboratory results, also known as the minimal reporting level, are greater with 2 ppt for PFOA and 4 ppt PFOS.

USDA FSIS started including PFAS testing in their regulated products in 2020 for beef and added pork, catfish, and chicken in 2021. Laboratory procedures allow for screening, confirmation, and concentration determination at levels of 0.5 to 125 ppb for most PFAS. Residue sampling results for 2020 or 2021 have not yet been published by FSIS.  

In the most recent 2021 total diet study conducted by the FDA, three out of 92 food samples were found to have detectable levels of PFAS. Across 5 data sets since 2019, less than 2% (10 out of 532) food samples have shown detectable levels of PFAS. At this time the FDA states that there is not any scientific evidence present to people from consuming any particular food based on PFAS contamination.

There are seven PFAS compounds regulated by EGLE under the “Michigan Safe Drinking Water Act” with established maximum contaminant levels of 8 ppt for PFOA and 16 ppt for PFOS found in drinking and ground water. Additionally, EGLE has set water quality values for surface water intended for drinking of 66 ppt for PFOA and 11 ppt for PFOS, while surface water not intended for drinking has values of 170 ppt for PFOA and 12 ppt for PFOS. The less stringent values for surface water set by EGLE are recognized as the concentration of PFAS that will not adversely impact aquatic life, recreational activities, and fish consumption. These levels may change based on the recently updated EPA levels.

Removal and potential impact on agriculture

Forever chemicals are nearly impossible to remove from the environment. Some research indicates that granulated activated carbon and reverse osmosis followed by nanofiltration may be effective methods of removing PFAS from water. Researching and developing additional methods for remediation will be critical to managing PFAS. Finding methods that are plausible for large scale contamination, including agricultural land will be difficult. Any currently available funding to compensate farmers that are impacted by PFAS contamination of land or livestock may be limited. Although PFAS contamination may be localized and more concentrated at certain sites, it is found everywhere and in nearly everyone. Becoming aware of the impacts of PFAS is important for all farmers. Expect more focused and randomized testing of land, water and meat products to occur in Michigan and nationally.   

A version of this story was initially published in the fall 2022 issue of  Michigan Cattleman’s Magazine.