March 2023
By Joel Tallaksen and John Larson, Renewable Energy Scientists at the WCROC
An emerging issue in agriculture is the discovery that a group of chemicals referred to as ‘forever chemicals’ is being found at low levels in food produced on some farms in America. At present, these long-lasting chemicals have been seen in only a few farms with heavy groundwater contamination. The concern is that these chemicals bioaccumulate, meaning that soil, water, crops and animals build up higher concentrations over time because the chemicals stay in food produced. As people are at the top of the food chain, we would likely accumulate the highest concentrations.
The full health impacts of these ‘forever chemicals’ or more technically, per- and polyfluorinated alkyl substances (PFAS), are not well understood. The PFAS chemical family has over 5000 different specific chemicals. These man-made chemicals are relatively new, but are being found in very low concentrations in human and wildlife blood samples globally. Each of these has the potential to affect human health differently. Therefore, it is uncertain how serious a health threat these chemicals pose.
Pioneered by Dupont and 3M, major production of PFAS began in the 1970s. The PFAS family of chemicals has unique properties that make things coated with it slippery. Common uses include products like Teflon, Scotchgaurd, and paper coatings. PFAS is also used in firefighting foam to fight flammable liquid fires at airports and other locations. A portion of the PFAS chemicals from these products have made their way into the environment over time.
The primary areas where contamination has occurred are near industrial sites handling PFAS, airports where firefighting foam is used, landfills with groundwater contamination, and in application of municipal sewage bio-solids. In Minnesota, testing by the Pollution Control Agency found that groundwater at almost all closed landfills tested had detectable PFAS levels. About half of closed Minnesota landfills have groundwater with PFAS above drinking water guidelines. Several were hundreds of times over the permissible level for PFAS in state guidelines. Since many of these were in rural locations, they do have the potential to impact agriculture.
Bio-solid fertilizer application is another potential source of PFAS contamination in Agriculture. Bio-solids are typically the composted waste from human sewage treatment plants. The PFAS bio-accumulates in the sewage treatment system and follows the bio-solid fertilizer product to farm fields where it is applied. Studies have shown that elevated PFAS concentrations are noticeable years after bio-solid fertilizer application. This is especially a problem where industrial wastewater is part of municipal sewage. Regular yearly applications of highly contaminated biosolids can result in land that is too contaminated to farm. This has shut down some dairies in Maine, where the milk was too contaminated for consumption. Contamination by PFAS substances in wastewater, landfill leachate, and groundwater prompted the Maine Legislature to adopt strict regulations.
While we are seeing PFAS contamination in our environment and it is an issue serious at a hand-full of farms across the nation, it is an open question whether it is a major long-term problem for the agricultural sector as a whole. Typical concentrations of PFAS are very, very low, often measured in parts per trillion. The concentration needed to cause health impacts are not known. However, the Current EPA acceptable concentrations have been lowered since 2016 as more information has become available on PFAS substances.
The larger issue is that these chemicals can remain in the environment for more than 2000 years and bio-accumulate in humans. Many US and European chemical manufacturers are starting to limit their PFAS production and use, either by choice, for liability reasons, or because they are being banned in a state/country. However, the question is whether PFAS will continue to bioaccumulate and lead to health impacts.
The agricultural sector must take into account that consumers are concerned about the food they purchase. Even if health impacts are not seen from food that contains low levels of PFAS, most consumers would prefer to purchase food that did not have PFAS chemicals. Therefore, it is critical for farmers to follow this issue and understand the potential for PFAS contamination on their farms.
As part of an effort to better understand the issues of PFAS and agriculture, the University of Minnesota, West Central Research and Outreach Center has recently started gathering available data from across the country to identify how Minnesota’s agricultural sector may be impacted by PFAS contamination issues and how they can be mitigated. This work is funded by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).