Tips for Taps Blog
Perfluoroalkyl substances–or PFAS as they are more commonly known–are fluorinated organic compounds that have had a tumultuous history. PFAS have been making headlines for several decades, but the true extent of their toxicity and prevalence has only recently come to the public spotlight. PFAS are incredibly useful in many products, but they are toxic and end up in our drinking water supplies. We turned to PFAS expert—Dr. Tom Bruton—for explanation, insight, and answers about these pervasive, persistent compounds.
SimpleLab: Tom, what is your background and area of focus?
Tom Bruton: My focus was as to whether in situ chemical oxidation is a viable treatment for PFAS in groundwater. We were trying to see if we could use chemical oxidants to break down PFAS, as they are very persistent pollutants. Unfortunately, they are also very resistant to most normal remediation–including bio-remediation, air stripping, and natural attenuation. None of these things tend to do much by way of treating PFAS contamination.
SL: What are PFAS and why are they an area of interest? What makes them particularly unique and how do they behave in the environment?
TB: The carbon-fluorine bond is the strongest bond in chemistry. Resistant to heat, oil, and water, PFAS make really good surfactants–and are subsequently useful. Their uses includes leather treatment, Teflon, structural fabrics, as well as many parts of cell-phones. They really are miracle materials, but the properties that make them so miraculous also make them problematic—resulting in their persistence in the environment and their surfactant nature. There is no known mechanism of environmental degradation [i.e. no sunlight, no bacteria, etc.]. They persist for geologic time and destroying them [in a lab] turns out to be expensive and hard.
SL: When did scientists begin studying PFAS and subsequently become concerned with PFAS contamination?
TB: Environmental scientists started studying them in the 1990s, as researchers started detecting them in the environment, across the globe. There were hints in the 1960s, as organofluorine chemicals were detected in blood bank samples from the Red Cross.
SL: What were some of the environmental scientists’ conclusions?
TB: Unfortunately, there were no straight or clear answers right away. However, things started to change around 2000. With the advancement of analytics with LC-MS [liquid chromatography–mass spectrometry], all of a sudden we could measure these things [PFAS] in the field. Scientists began finding them all over the world, even in places these compounds had no reason to pop up–indicating that they were persistent.
SL: Are there any uses that are of particular or immediate concern?
TB: In the past 5 years the use of firefighting foam has blown up as an issue because there are some places where this foam was used with incredibly high PFAS concentrations. Jennifer Field—an environmental and molecular toxicology professor at Oregon State University—examined military training firefighting areas. She found PFAS concentrations in groundwater in the Mg/L. [For reference, this is 6 orders of magnitude above what the EPA recommends]. There are many–100s if not 1000s–of military areas that have employed the same practices–although PFOS and PFOA [two subcategories of PFAS] have been phased out. What’s more is that these chemicals make there way off base and travel to other areas.
SL: How are PFAS bio-monitored?
TB: Normally, when we think about organic chemicals, we think about bioaccumulation and toxicity. PFAS behave uniquely. They don’t just partition into fat, they also partition into your blood, protein, and liver. This means that the traditional risk assessment models don’t accurately capture the risks. For bio-monitoring PFAS, they perform a blood test.
SL: There are two types of PFAS–long chain and short chain compounds. As long-chain PFAS have begun to be phased out, short chain compounds have been used as alternatives. Do the different types behave differently in the human body?
TB: The shorter chain PFAS are not as bio-accumulated quite like the long chain PFAS. As a result, they don’t stay in body as long, but they seem to have the same toxic mechanism. There is a hope that there is not time for these mechanisms to play out since the kidneys are able to filter them out.
SL: Can long chain PFAS be removed? Can short chain PFAS?
TB: GAC [granulated activated carbon] works relatively well–especially for the long chain compounds. But, GACs do not work as well on shorter chain PFAS.
SL: Any particularly notable legal cases or action related to PFAS contamination?
TB: There was a large lawsuit against DuPont in the early 2000s. The Washington Works Dupont plant had been making PFOAs there for decades. As a result, a lot of water was contaminated in the region. The lawsuit brought about a huge epidemiological study.
It subsequently produced the best series of studies of PFAS health studies and DuPont wound up settling for upwards of $600 million.
SL: What did this case entail? Why was it brought on and what did it conclude?
TB: It was a staggeringly large study. 69,000 people–all of whom received blood sampling and complete medical monitoring over about a dozen years. It was entirely paid for by Dupont. Two parties then studies studied the data and concluded a few things. High PFOA exposure can lead to: kidney and testicular cancer, thyroid disease, preeclampsia, high cholesterol, and ulcerative colitis.
SL: Was there any subsequent legislation or regulation resulting from the Dupont case?
TB: The Dupont studies established that at concentration 50 ppt [parts per trillion] results in the associated medical conditions.
SL: Legislation and regulation have been through a lot of drastic changes recently regarding PFAS recently? Is that unusual?
TB: Yes. As the level of concern rises, the government guideline levels around the world keep falling at unprecedented rates. It’s gone from 400 ppt, to 70 ppt, to 15 ppt. And, now Michigan is set to limit PFAS levels at just 5 ppt. The more we study them, the lower the levels of concern go and the extent of the contamination problem in the U.S. is only growing.
About Tom Bruton:
As a Science and Policy Fellow at the Green Science Policy Institute, Tom Bruton’s work focuses on the remediation of soil and groundwater contaminated with highly fluorinated chemicals. He holds a Ph.D. from the Department of Civil and Environmental Engineering from the University of California, Berkeley. He received both his bachelor’s and master’s degrees in Civil and Environmental Engineering from Iowa State University and Arizona State University, respectively.
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