Early results of a new study show liquid captured at landfills contained the highest levels of PFAS among liquid wastes sampled statewide in Wisconsin.
Since 2023, researchers at the University of Wisconsin-Madison have been collecting and analyzing samples from four waste materials that could be potential sources of PFAS in groundwater, which provides drinking water to two-thirds of state residents. It’s also a source of drinking water for around 800,000 private wells.
They collected nearly 50 samples from septage, wastewater, landfill liquid known as leachate and biosolids or sewage sludge that’s spread on farm fields. Researchers shared their findings during a recent meeting of the state’s Groundwater Coordinating Council, as well as with WPR.
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Kaitlyn Gruber, a fifth-year Ph.D. student at UW-Madison and the study’s lead author, said the identities and locations of facilities sampled are confidential under agreements reached with study partners. She said samples collected from 16 landfills, including six that remain open, showed total PFAS levels between 878 to 36,600 parts per trillion.
“Currently, the (Environmental Protection Agency) does not require any monitoring or reporting for PFAS in landfill solid waste or leachates,” Gruber told the council.
The EPA has established drinking water standards for PFAS, but no federal or state limits exist for the chemicals in groundwater. Wisconsin health officials have recommended PFAS standards in groundwater that mirror federal limits released last year, which include limits for two of the most widely studied chemicals at 4 parts per trillion.
PFAS, short for per-and polyfluoroalkyl substances, are a group of thousands of synthetic chemicals that have been linked to serious health risks that include kidney and testicular cancer. The so-called forever chemicals don’t break down easily in the environment.
Researchers say the study’s preliminary results are in line with other studies on landfill leachate, which is formed when rainwater filters through wastes. The EPA has found PFAS levels of up to 125,000 parts per trillion in municipal solid waste. One part per trillion is equal to a droplet of water in 20 Olympic-sized swimming pools, meaning even small amounts of PFAS can significantly affect human health.
One of the study’s goals was to conduct a forensic analysis of PFAS to pinpoint potential sources of contamination.
“Originally we were thinking maybe all landfill leachates could have a similar amount of the same PFAS, but it really wasn’t the case in this study,” Gruber said.
Gruber worked on the project with Christy Remucal, professor of civil and environmental engineering at UW-Madison.
“Overall, we found quite a bit of variability in both concentrations and the types of PFAS that were detected,” Remucal said.
Gruber said the findings may help lawmakers and state regulators make decisions about handling of different wastes.
“This leachate is pumped out of the landfill and then brought to a treatment plant” for further treatment, Remucal said.
The Wisconsin Department of Natural Resources does not bar disposal of PFAS waste at the state’s solid waste disposal facilities, Gruber said. They aren’t required to accept waste containing the chemicals either. State regulations require liners for landfills in Wisconsin to contain and collect leachate.
The study’s early findings also show PFAS levels in eight septage samples and seven samples of wastewater flowing into municipal treatment plants ranged between 30 and roughly 250 parts per trillion.
Researchers also examined biosolids, or sewage sludge, that are spread on farm fields as a nutrient-rich alternative to fertilizer. WPR previously reported the material is applied to more than half a million acres statewide each year.
Remucal said most sludge samples from municipal wastewater treatment plants had relatively low PFAS concentrations.
“In Wisconsin, there are limits on what can be land-applied, and there was only one of the 17 samples that exceeded those recommendations,” Remucal said.
Most levels ranged around 30 parts per billion, but one sample showed total PFAS concentrations of more than 1,300 parts per billion. The DNR’s interim strategy for biosolids dictates that the agency shouldn’t approve new land applications sites when combined levels of PFOA and PFOS exceed 150 parts per billion in order to limit risks to human health and the environment.
Researchers also found that the 33 chemicals detected in samples represent just a fraction of the extractable organic fluorine found within them. That organic fluorine is an indicator of other PFAS or fluorinated chemicals that aren’t currently identified through testing.
They hope to figure out the identity of other chemicals through further analysis, and the final results of their study will be released in the next few months.
Editor’s note: Language in this story has been updated to clarify that liquid tested in the study was captured by landfills.
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