MSU Extension PFAS Contamination in Agriculture

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 moment, we have not developed technology to clean PFAS out of the soil, so management strategies focus on planting crops that do not uptake high amounts of PFAS from the soil and switching to a clean water source.

Although the 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 and also how PFAS moves through our environment and is taken up into and interactions in crop and specific plant tissues.

Drinking Water

There are cost effective, practical options for removing PFAS contamination from drinking water. 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 

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.

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 MSU Extension for a confidential discussion of options.

Soil

At this time, there are no practical means of cost effectively reducing PFAS levels in agricultural soils. Strategies for growing crops on contaminated land right now include switching the contaminated crop that is being grown to one that is more likely to take up less PFAS. For example, corn kernels are less likely to incorporate PFAS, and so switching away from a hay crop that easily takes up PFAS to corn or other small grains is a viable strategy. Alternatively, the field could be switched to a different purpose other than crop production.

If animals are being held and are grazing on contaminated soils, there is some evidence that suggest PFAS can be taken up into the animal through multiple routes of exposure. In this situation, capping the soil with a barrier such as concrete, asphalt or rubber mats to reduce contact with contaminated soil may be helpful. MSU is currently undertaking this 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 that are found in plants is likely a result of uptake from contaminated irrigation water, soil, or both. If you took a sample that only involved feed or produce, and PFAS was detected, 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 the next mitigation steps.

If the animal feed is contaminated, it is best to stop feeding the animal this feed. 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 strategy is to use an alternative crop management strategy (for example, switch out a hay based diet for a corn based diet).

Perennial grasses and legumes tend to have a high potential to uptake PFAS from the soil readily. Therefore, grazing and harvesting grasses and legumes grown in contaminated soil are the highest contamination risk for animals.

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 are a more serious 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 the 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 guidelines for safe levels of PFAS in animal products intended for human consumption. Research into understanding of PFAS half-lives and elimination in the animals is evolving; farms with specific questions should reach out to MSU Extension for further discussion on your situation.