The Maine Center for Disease Control and Prevention (Maine CDC), in collaboration with scientists from Maine's Department of Agriculture, Conservation and Forestry and the Environment Protection Authority Victoria (EPA Victoria) in Australia recently published a scientific article in Toxics about per- and polyfluoroalkyl substances (PFAS). This study advances the ability to predict the transfer of PFAS from soil to livestock feed and then to beef cattle. The multi-year study demonstrates how the model can be used to help farmers modify management practices and reduce PFAS levels in beef products. This better enables farmers to meet health-based guidelines despite contaminated soils. These findings are valuable in helping Maine beef farmers manage PFAS contamination on impacted land.
PFAS are a large family of synthetic chemicals often referred to as "forever chemicals" due to their persistence in the environment and tendency to accumulate in living organisms. These compounds are commonly found in wastewater and have been detected in soils at Maine farms with a history of wastewater sludge (biosolids) application. Food products such as beef can become contaminated when cattle consume feed grown on PFAS-contaminated land.
A Dynamic Model for Understanding PFAS Accumulation in Beef Cattle
A beef cow on a Maine farm
EPA Victoria previously developed a model that can simulate how much of two PFAS compounds accumulate in beef cattle as they grow and are exposed to PFAS throughout their lifetime. Unique characteristics about this model:
- It looks specifically at the two PFAS called perfluorooctane sulfonic acid (PFOS) and perfluorohexane sulfonic acid (PFHxS).
- It simulates daily exposure and growth of the cows. This can therefore account for variability in exposure due to differences between farm fields where contaminated feed or water may be sourced.
Enhancing the Model: Adding PFDA and Validating at a Maine Farm
Using new data collected at Maine farms, Maine CDC toxicologists worked with EPA Victoria to enhance the model by incorporating an additional PFAS, perfluorodecanoic acid (PFDA), which had been detected in soil and beef products. The updated model was validated for use on farms where PFAS exposure occurs primarily through soil contaminated from historical land-spreading of biosolids. Other models had previously focused on contaminated drinking water from nearby use of firefighting foam.
DHHS PFAS Toxicologist Barbara Astmann taking a sample from a hay bale in a field
The Maine CDC applied the new model to a farm in central Maine and compared model predictions to PFOS and PFDA concentrations measured in beef cattle. Results demonstrated that the model accurately predicted PFOS and PFDA levels in beef cattle during periods of accumulation and depuration of these PFAS from animal tissues.
A Tool to Help Farmers Reduce Contamination in Meat and Remain Profitable
The Maine CDC and other co-authors of the study utilized the model to simulate potential changes to current farm management practices at the study farm. Management practices tested included altering the timing of when feed from fields with higher soil PFAS levels was fed to cattle relative to slaughter dates. This simulation helped to identify farm management practices that could reduce PFAS levels in meat while still allowing the farmer to use hay harvested from contaminated soils.