Critical Oversight: EPA’s Latest PFAS Guidelines Neglect Key Drivers of Water Contamination, According to a New Study

Earlier this year, the US Environmental Protection Agency (EPA) introduced proposed maximum allowable levels for six PFAS (per- and polyfluoroalkyl substances) in drinking water. These chemicals, commonly known as forever chemicals, have raised concerns due to their persistent nature. However, the draft standards presented by the EPA fail to address half of the PFAS compounds found in contaminated sites throughout the country.

A study conducted by a team led by the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has shed light on this issue. The findings, published in the journal Environmental Science & Technology, emphasize that the EPA’s proposed standards overlook a significant portion of the PFAS problem.

PFAS are prevalent in various products, including fire retardant foams, and have been accumulating in the environment since their initial invention by Dupont in the 1930s. Their widespread production by 3M since the 1950s has only contributed further to their environmental presence. Exposure to certain PFAS compounds has been linked to a range of health risks such as cancer, immune suppression, diabetes, and low infant birth weight.

PFAS compounds exist in two forms: precursor compounds and terminal compounds. The majority of monitored PFAS compounds fall into the terminal category. The EPA’s draft drinking water regulations solely focus on six terminal compounds, which are resistant to degradation under normal environmental conditions. Precursor compounds can undergo transformation into terminal forms through biological or environmental processes. Although numerous precursor compounds exist, most of them are not routinely monitored, and none are currently subject to regulation.

The United States military, as the largest global user of fire-retardant foams containing PFAS known as AFFF (aqueous film forming foam), plays a significant role in this issue. Military bases across the US and around the world have utilized AFFF, containing high levels of PFAS, for fire training drills and firefighting purposes for several decades. Consequently, AFFF usage stands as one of the primary sources of PFAS contamination in drinking water.

“Many PFAS precursors present in AFFF are difficult to measure,” remarks senior author Elsie Sunderland.

This new study “shows that they are slowly transforming into PFAS of health concern at AFFF-contaminated sites and contributing to downstream contamination.”

A significant portion of PFAS (per- and polyfluoroalkyl substances) found at military sites comprises precursors that are not accounted for in standard analytical methods. Researchers from Harvard, utilizing a method developed in the Sunderland lab, have addressed this gap by capturing all AFFF (aqueous film-forming foam) precursors. Their study focused on the contamination of two newly regulated PFAS chemicals, perfluorohexane sulfonate (PFHxS) and perfluorobutane sulfonate (PFBS), at a military base located on Cape Cod, Massachusetts.

The findings indicate that microbial precursor biotransformation in the soil sustains the presence of these contaminants in the groundwater. These precursors remain in the soil and gradually seep into the groundwater as terminal compounds, reaching concentrations thousands of times higher than the safe levels established by the EPA. The researchers used a computer model and field data to project that, in the absence of remediation efforts, widespread PFAS contamination of drinking water supplies near military facilities will persist for centuries.

Despite the potential risks to human health posed by existing aquifer contamination in the vicinity, a significant portion of PFAS compounds still resides in the soil surrounding these polluted areas. This underscores the urgent requirement for advancements in remediation technology that can effectively eliminate both precursor and terminal compounds. Since current regulations primarily target terminal compounds, the effectiveness of existing remediation techniques in addressing precursors remains uncertain.

In light of their findings, the researchers concluded that elevated PFAS exposure downstream from over 300 U.S. military facilities that employed fire-fighting foams may endure for centuries.

“The role of PFAS precursors in sustaining hazardous levels of contamination at Joint Base Cape Cod raises concern about whether exposure risks are underestimated near hundreds of other sites where they are not measured,” comments first author Bridger Ruyle.

The deadline for the public comment period on the Environmental Protection Agency’s (EPA) draft regulation for PFAS in drinking water is May 30. While this marks a positive step forward, it’s important to acknowledge that there are thousands of different PFAS chemical structures, with several hundred already found in the environment, as pointed out by Sunderland.

Additionally, in a recently published study in Environmental Science & Technology, Sunderland’s research group demonstrated that the presence of military fire training areas in a watershed can serve as a reliable indicator of PFAS contamination in the local community’s drinking water supply.

However, it is crucial to note that certain groups face a higher risk than others. A forthcoming publication by the Sunderland lab reveals significant sociodemographic disparities in PFAS exposure and proximity to PFAS sources across the country.

Image Credit: Michael Salerno