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MPART investigation yields new data on PFAS

The Michigan PFAS Action Response Team's (MPART) effort to eliminate PFAS contamination in municipal wastewater biosolids and investigate historical land application sites across the state has led the Michigan Department of Health and Human Services (MDHHS) and the Michigan Department of Agriculture and Rural Development (MDARD) to issue a consumption advisory regarding beef from a farm in Livingston County.

The MPART investigation yielded new data supporting the need for additional national research into the agricultural use of biosolids containing high levels of per- and polyfluoroalkyl substances (PFAS) that can result in these chemicals being absorbed by crops and used as animal feed.

Although the farm's beef results didn't fit current USDA criteria for a recall or market withdrawal, MDHHS determined that prolonged consumption of the beef from this farm could increase PFOS levels in the human body. MPART agencies MDHHS and MDARD shared these results with the farmer and, out of an abundance of caution, are helping the farm notify customers. MDHHS is also offering the farmer financial assistance to reimburse customers who purchased this beef. The farmer is cooperating with state agencies and has removed the farm's stocks of beef and impacted cattle from commerce.

PFAS are a group of man-made chemicals used in thousands of applications globally, including firefighting foam, food packaging and many other consumer and industrial applications. They do not breakdown easily in the environment and are known to accumulate in the tissues of living organisms. Associated health effects include reduced fertility, high blood pressure in pregnant women, higher cholesterol and developing certain types of cancer.

Building on research conducted in other states on dairy cattle exposed to high levels of PFAS-contaminated water, MPART scientists with the Michigan Department of Environment, Great Lakes, and Energy (EGLE) and the Michigan Department of Agriculture and Rural Development (MDARD) collected data showing a PFAS compound known as perfluorooctane sulfonic acid (PFOS) can also bioaccumulate in the meat of beef cattle that exclusively received feed grown in fields fertilized with industrially impacted biosolids containing high concentrations of PFAS.

Under an interim strategy launched in 2021, Michigan began prohibiting the land application of industrially impacted biosolids containing more than 150 parts per billion (ppb) of PFOS and now requires testing of biosolids before land application.

"Michigan's pioneering work to trace PFAS in wastewater back to industrial facilities provided us with the data we needed to halt the land application of heavily impacted biosolids until the sources of PFAS in wastewater were addressed," said MPART Executive Director Abigail Hendershott. "This data also provided us with the information to further investigate how this legacy contamination can cycle through the ecosystem. Our team focused their investigation on a small farm in Livingston County that had unknowingly applied industrially impacted, PFAS-containing biosolids from the City of Wixom to fields used to grow feed and provide pasture for beef cattle being sold direct-to-customers locally."

The farm investigation stems from the 2018 discovery of high levels of a PFOS in the wastewater handled by the City of Wixom wastewater treatment plant in Oakland County. Treated wastewater samples leaving the plant contained 269 parts per trillion (ppt) PFOS and the biosolids material created during the treatment process contained 2,150 ppb of PFOS. This contamination was traced back to a chrome plating facility served by the plant. EGLE and the City of Wixom worked with the plating facility to install carbon filtration technology which reduced PFOS discharges by 99 percent.

Based on the high levels of PFOS in the Wixom treatment plant's biosolids, MPART researchers selected it along with several other wastewater treatment plants across the state for a 2019 study of the environmental impacts of the agricultural use of PFAS-containing biosolids.

In 2019, EGLE tested soil and water at several farm fields which unknowingly received PFAS-containing biosolids from the City of Wixom. EGLE also installed monitoring wells at one location and continued to test groundwater and residential well water throughout 2020 and 2021.

In March of 2021 MPART received data from a shallow groundwater monitoring well at the Livingston County farm showing an exceedance of the state's groundwater criteria for another PFAS compound known as perfluorooctanoic acid (PFOA). This led to a residential well sampling effort near the farm that yielded no testing results above Michigan's drinking water standards.

MPART, also in 2019, collected sorghum plants, haylage and corn silage from the farmer grown on fields at the farm. The fields were exclusively used to grow feed and serve as a pasture for beef cattle. MPART scientists then embarked on a two-year effort involving the US Food and Drug Administration (FDA), and a private laboratory to develop a crop processing method and to adapt a laboratory method to test for PFAS in crops since no standard methods existed.

In addition, MPART scientists consulted with the FDA about the interpretation of the data showing PFAS in crop samples collected from the Livingston County farm which received the largest and most frequent applications of the Wixom treatment plants biosolids. As a result, MDARD developed a risk assessment model to predict the uptake of PFAS by livestock that had grazed on and received feed from the same fields, which indicated the potential for PFAS to be present in the meat.

Because there are no state or federal standards for PFAS in crops and meat, MPART briefed the farmer on the crop findings in November 2021 and received permission to test manure and additional soil on the farm in December 2021. These tests found levels of PFAS in the manure and levels of PFAS in the soil consistent with the 2019 data.

Since the MDARD model had not been widely performed and actual beef samples were needed to verify the modeling, the farmer also gave permission for frozen beef cuts to be analyzed in December 2021. The beef cuts were tested in January at the USDA Food Safety Inspection Service (FSIS) laboratory and the analysis found an average PFOS level of 1.9 ppb in the beef. These results were lower than USDA's current health screening value and lower than beef samples previously tested in other states.

"Although the farm's beef results didn't fit current USDA criteria for action, the MPART agencies agreed that consumers should know, so we've shared these results with the farmer and are helping the farm notify customers and providing financial assistance," Hendershott said. "Based on MPART's statewide investigation over the past four years into industrially impacted biosolids, we believe it is a rare occurrence here in Michigan unlikely to be repeated because of EGLE's aggressive reduction of PFAS sources to municipal wastewater treatment plants (WWTPs) and biosolids. With the current required testing of WWTP's and biosolids, industrially impacted biosolids will be identified before any application to fields is made. Having said that, our food supply is global, and we need help at a national level on testing and standards to protect the public from the unknown risks of PFAS entering the food chain."

In addition to its pioneering work to understand the presence of PFAS in biosolids, MPART continues to work to identify and eliminate pathways for PFAS to enter Michigan's water sources.

Launched in February 2018, EGLE's Industrial Pretreatment Program (IPP) initiative was developed to evaluate the potential for PFAS from industrial sources to pass through municipal wastewater treatment plants and enter drinking water sources in the state.  Data collected over a two-year period showed 46 percent of the state's 96 municipal wastewater plants with an IPP did not have any significant industrial sources of PFAS while 23 percent were processing PFAS containing wastewater but the treated wastewater leveling the plant were below state water quality values. PFAS containing industrial wastewater was discovered entering 31 percent of these 96 treatment plants which resulted in the treated wastewater leaving the plant to exceed state water quality values. Through reduction efforts at industrial sources, currently 92 percent of municipal wastewater plants with an IPP are meeting the state water quality values.

Also in the fall of 2018, EGLE conducted a statewide study of 42 wastewater treatment plants to evaluate the presence of PFAS in their intake and discharge waters, and the associated biosolids generated during processing. In addition, EGLE screened 29 land application sites to further the understanding of the potential environmental impacts from the biosolids.

In the absence of federal standards, EGLE in 2021 launched an Interim Biosolids Strategy requiring sampling and evaluation of biosolids prior to land application. The strategy was designed to prevent future land applications of industrially impacted biosolids and continue to drive down PFAS concentrations wastewater plant biosolids as quickly as possible.

In addition to the state's IPP initiative, Michigan recently completed the nation's largest effort to collect and safely dispose of PFAS-containing firefighting foam that has been tied to contamination of drinking water near airports and military bases. Firefighting foam from a military base has been tied to milk contamination in other states. MPART is also active in testing fish and deer to protect people from PFAS contamination in these game species.

EGLE's IPP reports can be found here:

Caption: Soil sampling effort in December 2021 at the Livingston County farm.