cows in field

Assessing PFAS Contamination on Dairy Farms in Maine

By Rick Kersbergen, Extension Professor, U of Maine Cooperative Extension, Sustainable Dairy and Forage Systems This article is reprinted with permission

It is hard to escape the news about PFAS contaminated soils, crops, and milk in Maine. For dairy farmers, whose land was often utilized for the legal spreading of biosolids, the scrutiny, frequent accusations, and worry can be overwhelming. As we move closer to another cropping season, there are some steps you can do to minimize the impact of PFAS contaminated soils on your crops and the subsequent milk your cows produce.

The best place to start is to learn more about PFAS in Maine. To do that, a group of service providers and crop consultants put together this guide: Guide to Investigating PFAS Risk on Your Farm: The complete version can be found at this link:

Maine CDC, Maine DEP, Department of Agriculture Conservation and Forestry, Cooperative Extension and MOFGA have been investigating forage crop uptake on two dairy farms in Maine to get a better understanding of the potential for contaminated soils to impact the levels of PFOS in milk (PFOS is the PFAS we find most prevalent in milk). While this research is preliminary, we have been able to use the information and data to alter the cropping practices on one farm to reduce the level of PFOS to acceptable levels so they can ship milk again.

What has been discovered?

Forage grasses and legumes tend to have a high potential to uptake PFAS from the soil and therefore from a crop management perspective grasses and legumes grown in contaminated soil have the highest risk as a potential contamination source for milk.

Corn silage has a lower potential to uptake PFAS and hence has a lower potential to contaminate milk

Corn grain has an even lower potential, so corn harvested as grain, snaplage or high moisture ear corn will have much lower levels of PFAS than corn silage

Although not quantified, the potential for soil contamination or dirt in your forages harvested from contaminated fields will increase the risk for contaminated milk.

We have found a lot of variation in uptake levels of PFAS into plants, and this is an area that needs further investigation.

What should you do as a concerned dairy farmer?

Evaluate the potential for contamination of soils on your farm and the acres you lease for forage crop production. Review the history of the fields and look for biosolid applications. Maine DEP is using historical records of licenses and volume of materials to prioritize what fields they will sample first this spring and focus on what they label “Tier 1” sites. The map on the EGAD Septage and Sludge Sites page may help you locate what fields and licenses were recorded.

For fields that have a history of biosolid applications, consider the following forage crop production and harvest changes for 2022.

Consider testing the suspect field soils for PFAS levels. If the suspect fields are near your well, consider getting that tested as well. The testing is expensive, and the sample collection process must be done carefully. There are several private consultants that have been testing this past summer. Additionally, as indicated before, Maine DEP will be testing priority sites. Additional funding for testing may become available through MDACF and several non-profit organizations.

If you find or suspect the potential of higher than background levels in the soil and it is currently producing a perennial forage (grass/legume), consider rotating that field into corn silage. If soils are highly contaminated, even corn silage could also result in contaminated milk, so knowing the levels in the field may help you decide to go to suggestion #3.

If you feel that you have the potential to do so, plant the field to corn, and harvest the crop as either snaplage, high moisture ear corn or even corn grain. Our research has shown that minor amounts of PFAS are taken into the grain portion of the plant. Snaplage can be easily harvested and stored in bunker silos, so the investment in moving to this harvest and storage method would only require the use of a snapper head on your chopper and good bunker silo management.

If the suspect field does remain in a perennial forage, make sure you reduce the potential for soil contamination by raising your mower and making sure that rakes, tedders, and pick-up heads are set high to eliminate soil contact.

If you are grazing the contaminated fields, do not allow the fields to become over-grazed, as that too will contribute to soil contaminated ingestion of feed and lead to high levels of PFOS in milk. The general recommendation would be to not use contaminated fields for grazing since the transfer from soil to feed to milk will be high.

Some farms have discussed harvesting the contaminated feed and using it for feeding heifers or dry cows. This is not a solution to the problem and should be avoided. By monitoring fresh heifers at one of the dairy farms we have been working with, we have found that while the heifers were on clean feed for 8-10 months after being fed contaminated feed (both milk when they were calves and forage), their milk contained high levels of PFOS when they first freshened!

The research group will be continuing to investigate the transfer factors for forage crops this coming season so we can continue to make better forage crop harvest decisions to minimize risk.

There are some safety nets for dairy producers if your milk is considered adulterated by PFOS. The Dairy Indemnity Payment Program (DIPP) is a temporary option, especially if there is a way to depurate your herd. While stressful, we have successfully done that with one dairy herd in Maine this past year. While these contaminants are considered “forever chemicals”, they are not forever in your cows, and they can again produce quality milk once they are on non-contaminated feed. Many state and non-profit organizations are organizing additional relief programs that will soon become available.

Feel free to reach out with questions as you plan for this coming season. Knowing your soil levels will help decide the best course of action. The current situation is stressful for everyone involved. Your farm may need to think about forage budgeting and feed requirements moving forward to make sure your herd size will fit the available forage you can safely harvest this coming season.

Knowing and evaluating all your options is the best path forward.

Rick Kersbergen can be reached by email,, or by phone, 207.342.5971