Mitigation

Strategies for Dealing with Contamination

If you have reason to suspect PFAS contamination on your farm, there are steps you can take to manage the risk. At the present time, there are no cost effective technology to remove or destroy PFAS in the soil on a large scale, so management strategies focus on planting crops that do not uptake high amounts of PFAS from the soil, growing ornamental crops and switching to a clean water source. 

Because of the lack of clarity around what level of PFAS is harmful in agriculture products, it can be difficult to know when and how to take action. This section attempts to provide some guidance, but this guidance is limited by the gaps in our current knowledge related to thresholds that contribute to PFAS toxicity, how PFAS moves through our environment, and how it is taken up and distributed into crops and specific plant tissues. 

Drinking Water

There are cost effective, practical options for removing PFAS contamination from drinking water on a household scale. The most effective water filters that reduce PFAS are reverse osmosis (RO) systems and granular activated carbon (GAC) filter systems. There are different types of water filters that are NSF/ANSI 53 certified for reducing PFOA and PFOS and reverse osmosis systems that are NSF/ANSI 58 certified to reduce PFOA and PFOS in drinking water.  Learn more about filters for drinking water at: https://www.michigan.gov/pfasresponse/drinking-water/filters  

On a large scale, such as providing animal drinking water for a large dairy farm, these solutions are cost restrictive. In the absence of site-specific information, it would be prudent to assume that the PFAS levels in drinking water for animals should be at the same acceptable level as for humans to protect the food supply. 

Irrigation Water

At this time, there are no practical mitigation options for irrigation wells that are drawing large amounts of surface or ground water contaminated with PFAS. Switching water sources or using a well that draws from a different aquifer should be considered. Contact Faith Cullens-Nobis at MSU Extension for a confidential discussion of options. 

Soil

At this time, there are no cost effective solutions for reducing PFAS levels in agricultural soils through removal or destruction. Strategies for growing crops on contaminated land  focus on switching the contaminated crop that is being grown to one that is less likely to take up PFAS. For example, corn kernels are less likely to accumulate PFAS then the leaves of the plant are, so utilizing a contaminated field for corn grain instead of corn silage is a viable strategy. Alternatively, the field could be switched to a different purpose other than crop production, such as cut flowers, landscaping plants or solar panels. 

If animals are being held and/or are grazing on contaminated soils, there is evidence that PFAS can be taken into the animal through crop consumption and/or inadvertent soil consumption. MSU is currently undertaking research to better understand the best mitigation strategy for this type of situation. Before making drastic changes to your farming practice and/or animal husbandry, it is recommended to work confidentially with MSU Extension to understand your options. 

Plants

Elevated PFAS levels found in plants are likely a result of uptake from contaminated irrigation water, soil, or both. If there are laboratory results showing contamination in animal feed or produce, it would be prudent to follow up with testing of soil and irrigation water to determine the source of the contamination. This will provide information on steps towards mitigation. 

If the feed is contaminated, stop feeding the animal this feed if at all possible. However, if this option is not manageable, a potential strategy would be to dilute affected feed with “clean” feed, thereby lowering the overall PFAS concentration that livestock are consuming. Another long-term strategy may be to use an alternative crop feeding strategy (for example, switch out a hay-based diet for a corn-based diet). 

Perennial grasses tend to have a high potential to uptake PFAS from the soil readily, therefore, grazing and harvesting grasses grown in contaminated soil are a high contamination risk for animals. Annuals, such as oats, and alfalfa have been shown to accumulate less PFAS than perennial grasses.  

There is research indicating that PFAS accumulate more in the roots and leaves of the plant (Ghisi et al., 2019). Additionally, several studies have shown that first cutting of grasses and legumes contain less PFAS then second cutting, presumably because of a higher leaf to stem ratio (Ghisi et al., 2019). Corn grain has a lower potential of PFAS uptake, so corn harvested as grain, snaplage, or high moisture ear corn will have much lower levels of PFAS than corn silage. 

Contaminated produce products presents a problem because there is a direct route to human consumption. At this time, there are no guidelines for safe levels of PFAS in products intended for human consumption. However, we issue the same advice to human consumption that we do for animal feed and water; eliminate the source of contamination (provide clean water and soil). These strategies will likely require modification of farming practices, crop selection, field selection, irrigation source, harvest approaches, etc. 

Animals

If water, soil and/or feed sampling has indicated PFAS contamination on your farm, the best strategy for animal product production is to provide clean feed and water as quickly as possible (see strategies above). There are no federal guidelines for safe levels of PFAS in animal products intended for human consumption. Animals will depurate accumulated PFAS over time, however there is a large variation based on specie, stage of growth and production, age, and contamination levels. Research into understanding of PFAS half-lives and elimination in the animals is evolving; farms with questions should reach out to Faith Cullens-Nobis with MSU Extension for further discussion on your situation.