Per- and polyfluoroalkyl substances (PFAS), commonly referred to as forever chemicals, are persistent pollutants with significant environmental and health risks. Unlike many other substances, PFAS do not naturally degrade and can persist in the environment for centuries. Given their extensive use across industries and potential toxicity, concerns have been raised about their long-term impact on ecosystems and human health.
A recent study conducted by Harvard University found that unmonitored PFAS can accumulate and remain in the environment for extended periods, reinforcing the urgency of addressing this issue.
Earlier this year, the United States Environmental Protection Agency (EPA) proposed provisional regulations to establish maximum allowable levels for six PFAS in drinking water. However, these regulations only cover half of the PFAS compounds found at pollution sites throughout the country.
Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) discovered this information and published their findings in the journal Environmental Science & Technology.
PFAS are present in various products, including fire retardant foams, and have been accumulating in the environment since their inception by Dupont in the 1930s, followed by widespread manufacturing by 3M in the 1950s. 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 and terminal forms. Most of the PFAS compounds monitored so far are terminal compounds, which do not degrade naturally in the environment. The EPA’s draft drinking water rules address six terminal compounds. However, precursor compounds can undergo transformation through biological or environmental processes and become terminal forms. There are numerous precursor compounds, most of which are not routinely monitored or regulated.
The largest global user of fire-retardant foams containing PFAS, known as AFFF (aqueous film forming foam), is the U.S. military. For decades, military bases across the United States and worldwide have utilized AFFF containing high levels of PFAS for fire training drills and firefighting. Consequently, AFFF use represents a major source of PFAS contamination in drinking water.
According to Elsie Sunderland, the senior author of the study and a professor at SEAS, “Many PFAS precursors present in AFFF are difficult to measure. This work shows that they are slowly transforming into PFAS of health concern at AFFF-contaminated sites and contributing to downstream contamination.”
Standard analytical methods often overlook the PFAS precursors found at military sites. To address this, the Harvard team employed a method developed in the Sunderland lab that captures all precursors in AFFF. Using this approach, they modeled the expected duration and contribution of precursors to groundwater contamination at a military base on Cape Cod, Massachusetts. The study revealed that microbial precursor biotransformation in the soil sustains the contamination of two newly regulated PFAS chemicals (perfluorohexane sulfonate: PFHxS and perfluorobutane sulfonate: PFBS). These precursors remain in the soil and subsequently leach into groundwater, resulting in terminal form concentrations thousands of times higher than the safe levels established by the EPA.
Based on computer modeling and field data, the researchers projected that without remediation, widespread PFAS contamination of drinking water supplies near military facilities could persist for centuries. Despite potential risks to human health from nearby aquifers, the majority of PFAS remains in the surrounding soils. This highlights the urgent need for remediation technologies capable of effectively addressing both terminal and precursor compounds. Current technologies primarily target terminal compounds, and their efficacy in remediating precursors remains uncertain.
The researchers concluded that elevated PFAS exposures downstream of over 300 U.S. military facilities that employed fire-fighting foams could similarly endure for centuries. This raises concerns about potential underestimation of exposure risks in areas where PFAS levels are not measured, as pointed out by Bridger Ruyle, the first author of the study and a former doctoral student in Sunderland’s lab.
The public comment period for the EPA’s draft PFAS drinking water regulation closed on May 30. While a step in the right direction, it is crucial to note that there are thousands of PFAS chemical structures, and several hundred have already been detected in the environment, underscoring the need for continued research and action, according to Sunderland.
In a related study published in Environmental Science & Technology, Sunderland’s group demonstrated that the number of military fire training areas within a watershed serves as a reliable predictor of PFAS contamination in community water supplies. The study also uncovered significant sociodemographic disparities in PFAS exposures and proximity to PFAS sources across the country.
References:
- “Centurial Persistence of Forever Chemicals at Military Fire Training Sites” by Bridger J. Ruyle, Colin P. Thackray, Craig M. Butt, Denis R. LeBlanc, Andrea K. Tokranov, Chad D. Vecitis, and Elsie M. Sunderland, 15 May 2023, Environmental Science & Technology. DOI: 10.1021/acs.est.3c00675
- “Sociodemographic Factors Are Associated with the Abundance of PFAS Sources and Detection in U.S. Community Water Systems” by Jahred M. Liddie, Laurel A. Schaider, and Elsie M. Sunderland, 15 May 2023, Environmental Science & Technology. DOI: 10.1021/acs.est.2c07255
The study received funding from the Department of Defense Strategic Environmental Research and Development Program and the U.S. National Institute for Environmental Health Sciences Superfund Research Program. Additional support was provided by the U.S. Geological Survey Toxic Substances Hydrology Program.
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Frequently Asked Questions (FAQs) about PFAS contamination
What are PFAS and why are they a concern?
PFAS, also known as per- and polyfluoroalkyl substances, are a group of persistent pollutants that pose significant environmental and health risks. They are called “forever chemicals” because they do not break down naturally and can persist in the environment for centuries. Their widespread use in various industries, coupled with their potential toxicity, has raised serious concerns about their long-term impact on ecosystems and human health.
What did the recent study by Harvard reveal about PFAS contamination?
The study conducted by Harvard found that unmonitored PFAS can accumulate and persist in the environment for centuries. It highlighted the need to address the oversight in EPA’s PFAS rules by identifying a key contaminant source that was not covered by the proposed regulations. This research underscores the urgency of addressing PFAS contamination and developing effective remediation technologies.
How do PFAS contamination and drinking water relate to each other?
PFAS contamination poses a risk to drinking water supplies, especially near military facilities that have historically used fire-fighting foams containing PFAS. These foams are a significant source of PFAS contamination in groundwater. The study revealed that without remediation, widespread PFAS contamination of drinking water supplies near military bases could persist for centuries, emphasizing the need for robust measures to ensure drinking water safety.
Are there health risks associated with PFAS exposure?
Yes, exposure to certain PFAS compounds has been linked to various health risks, including cancer, immune suppression, diabetes, and low infant birth weight. The potential long-term health effects of PFAS exposure are a cause for concern and highlight the importance of addressing and minimizing exposure to these harmful substances.
What are the limitations of the EPA’s current PFAS regulations?
The EPA’s draft drinking water rules for PFAS focus primarily on six terminal compounds that do not degrade naturally. However, the study revealed that there are many precursor compounds, most of which are not routinely monitored or regulated. These precursors can transform into terminal forms, contributing to contamination. The current regulations overlook these precursors, emphasizing the need for comprehensive regulation and remediation technologies that can address both precursor and terminal forms of PFAS.
How can we address PFAS contamination and its long-term effects?
Addressing PFAS contamination requires a multi-faceted approach. It involves implementing stricter regulations and monitoring for a broader range of PFAS compounds, including precursors. Additionally, developing and implementing effective remediation technologies capable of cleaning up both precursor and terminal forms of PFAS is crucial. Continued research, public awareness, and collaboration between government, scientific institutions, and communities are essential to mitigate the long-term effects of PFAS contamination.
More about PFAS contamination
- Study on PFAS Contamination and Persistence – Read the full study conducted by Harvard on the centurial persistence of PFAS at military fire training sites.
- Environmental Science & Technology Journal – Access the journal where the findings of the Harvard study and related research on PFAS were published.
