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SciLine Interviewed: Dr. Jamie DeWitt, an associate professor of pharmacology and toxicology at East Carolina University. She discussed what is known about the health effects of PFAS exposure; and the lack of consensus on what level of exposure is “safe.”
Interview with SciLine
What are PFAS?
JAMIE DEWITT: PFAS is actually an acronym for a class of close to 10,000 individual substances that are defined as per- and polyfluoroalkyl substances. They are used in a phenomenal amount of products and processes, mostly as surfactants or as raw materials for agents that confer nonstick, stain-, grease- and water-repellent properties.
What is known about the health effects of PFAS exposure, and how have scientists learned about these effects?
JAMIE DEWITT: So when we ask questions about what exposure to PFAS does to human health, we do throw – do so through several lines of inquiry. One way is by performing epidemiological studies of people who have been exposed through their jobs, where they live or even through everyday activities, and then asking, is their exposure linked to health effects? Another way that we can ask questions about the potential effects of PFAS exposure on human health is by performing studies with laboratory models. And through these studies with laboratory models, we can ask questions about individual PFAS and very specific types of health effects, such as effects on the immune system or effects on development or effects on the heart, for example. And when we tie all this information together, we start to develop an overall picture of what health effects really look like following PFAS exposure.
Most of what we know about the toxicity of PFAS comes from the study of a fairly small number of PFAS known as perfluoroalkyl acids, or PFAAs. These include PFAS like PFOA or PFOS, which most people have probably heard of. And from studies of people and studies of experimental models, we now have pretty good evidence linking PFAS exposure to high cholesterol, a suppressed immune system, effects on development, effects on liver health, effects on thyroid function and other endocrine functions, effects on pregnancy and people’s ability to get pregnant, as well as some effects on ulcerative colitis or autoimmune endpoints. Emerging data suggests that there might be a whole bunch of other health effects, which is one reason we call PFAS multisystem toxicants.
Who is most at risk of being harmed by PFAS?
JAMIE DEWITT: So people are pretty concerned about PFAS now because if you look at some of the information about where they’re being found, they’re being found almost everywhere. I undoubtedly have PFAS in my body. And some estimates indicate that close to 99% of people in the U.S. have one or more PFAS in their body. But who’s most at risk from exposure? Well, we know people with levels from occupational exposure may have higher risk of health effects. People living in areas with higher environmental contamination may have an increased risk of health effects. But there also may be individuals who are slightly more susceptible because they’re very young or very old or have compromised immune systems. We’re still trying to figure out who the most sensitive people are. But it looks as if those with high exposure and those who are developing, such as infants and children, seem to be more sensitive to the health effects of PFAS.
What level of exposure to PFAS is safe?
JAMIE DEWITT: Really, the question is what level of exposure is acceptable? Right now the U.S. EPA has said that a combined concentration of PFOA and PFOS of 70 parts per trillion in drinking water, if you’re exposed to that amount over the duration of your life, that’s not anticipated to be associated with any adverse health effects. Some states have come up with lower concentrations in drinking water, such as six parts per trillion or 13 parts per trillion for individual PFAS. Some organizations have said one part per trillionaire or 0.1 part per trillion. Really, what it comes down to is that a very, very low level of PFAS is what should – we should be striving for in the environment and in our bodies, and that would be acceptable. But really, the safe level is zero. We shouldn’t be exposed to PFAS at all.
How are PFAS chemicals regulated?
JAMIE DEWITT: Here in the United States, we don’t have federal regulations for PFAS in drinking water, for example, at this time. Some individual states here in the United States have established maximum contaminant levels for certain PFAS in drinking water. In other words, that level should not be exceeded because a level above that level is considered to be with potential health risks. Some countries have proposed regulations, and the U.S. EPA is supposedly considering establishing a nationwide maximum contaminant level for PFAS in drinking water. But right now in the United States, there really are no regulations, at least in drinking water.
How do you think PFAS should be regulated?
JAMIE DEWITT: If we evaluate PFAS one by one by one and regulate them one by one by one, and let’s say it takes three to five years to really, thoroughly evaluate one individual PFAS, multiply that by 10,000, and that’s how long it would take us to evaluate each and every PFAS. And so an appropriate approach would be to manage them as a class. We have enough information on the persistence, on the bioaccumulation potential and on the toxicity of a large number of PFAS that makes us confident we can regulate them as a class. And to minimize the potential economic impacts from regulating PFAS as a class, we could apply a concept known as the essential-use concept to start to phase out those PFAS that are not essential for various use categories. Do PFAS need to be in ski waxes? Do PFAS need to be in cosmetics? Do PFAS need to be in turnout gear for firefighters? If the answer, unequivocally, is yes, then that’s essential, and essential means necessary for the health, safety or functioning of society.
What can be done to reduce the amount of PFAS being produced?
JAMIE DEWITT: To reduce the amount of PFAS that are being produced, society really has to ask what uses of PFAS are essential for the health, safety and functioning of society. This is known as the essential-use concept, and it was really developed under the Montreal Protocol for ozone-depleting substances. If we applied this type of thinking to PFAS, we could start to phase out those PFAS that are not essential for particular uses and start to reduce the overall amount of PFAS being produced. We also have to understand that when we do phase out PFAS in one part of the world, another part of the world may pick up production. So we as a society on a global level, need to work better together to ensure that the burden of exposure and production isn’t shifted to other countries and that we work together to phase out unessential uses of PFAS.
What do you personally do to prevent exposure to PFAS?
JAMIE DEWITT: In terms of what I do personally to prevent my exposure to PFAS, when I work with them in the laboratory, I make sure to wear appropriate personal protective equipment. And we also do everything possible in the laboratory to minimize how much PFAS waste we produce because I know that that PFAS waste may have an impact on somebody else downstream from me in another part of the environment from me. I also try to educate myself about where my water comes from. I know that my water comes from the Tar River, and I can look up information for my utility company about the last time they measured PFAS in water from the Tar River. So I can find out what PFAS and what amounts are in my drinking water. I also try to educate myself about companies that have really made a commitment to phase PFAS out of their products and processes, and I try to purchase products from those companies so that I can support their environmental stewardship and their moves towards sustainability.
I also work with organizations to help to educate people about sources of PFAS, how we can manage PFAS, their toxicity and how we can phase out nonessential uses of PFAS. In my home, for example, I don’t have a special kind of filter because I know that the water that I drink contains fairly low levels of PFAS. But if I wanted to install a filter, I would look up information about the types of filters that might be useful. A really nice study came out of Duke University and North Carolina State University that asked questions about specific point-of-use filters – or filters that you can screw into your faucet – that people could use in their homes. And they found that reverse-osmosis filters do a really good job of filtering out at least the PFAS that they evaluated in their paper. So I might consider installing a reverse-osmosis filter, but they can be quite expensive. So if you don’t have the funds to do so, you might want to consider another more affordable type of filter, at least to help reduce some PFAS.
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