Estimated read time: 5.5 minutes
Ocean Sewage Alliance co-hosted a panel with our partners at the Nature Conservancy (TNC) to answer questions about PFAS and PFOS. Our panel included a journalist, a chemist, an environmental microbiologist, and a representative from a utility that takes municipal biosolids (aka our poop) and turns it into fertilizer for commercial use.
PFAS and PFOS are per- and polyfluorinated substances, known collectively as PFAS or forever chemicals. They are called forever chemicals because they form very strong bonds at the molecular level, allowing them to stay around for a very long time (possibly forever) and even accumulate in the environment and our bodies.
Forever chemicals get into our poop and the waste stream in a few ways. They are in the water we drink, many of the household products we use every day, and our food is packaged in them. PFAS are also in industrial waste — think manufacturing, construction, and flame retardants — that often ends up in a landfill. The leachate, or toxic liquid that seeps from that landfill, is piped to the wastewater treatment plant, combining with our toilet waste.
We asked our expert panel tough questions. Here are the top four.
Why should we care about PFAS in biosolids?
Answer: We heard the word ‘ubiquitous’ a lot our webinar. In short, PFAS and PFOS are everywhere. The concern about biosolid contamination has come from several news articles and a recent report issued by EPA. Maine recently banned the application of biosolids because of concerns about PFAS contamination and accumulation in agricultural soil.
Dr. Kris Hansen said, “My group [at 3M] and I were credited with discovering the global contamination of PFAS and PFOS specifically, which was our 1st compound. We characterized a large handful of fluorochemicals that are present in over 98% of the population in the US. We also developed methods to look at PFAS exposure in the environment, in critters, in river water, in soil.”
Dr Ian Pepper spoke about PFAS in biosolids, stating, “PFAS are so ubiquitous that they inevitably end up in wastewater and, ultimately, in biosolids.”
Dr. Bryn Nelson remarked, “I don't think that many people understand that PFAS are literally on the food wrappers of the food they eat.”
What are the human health concerns about PFAS?
Answer: Because these chemicals do not break down easily. They stay in our environment and in our bodies. About fifteen of them are known carcinogens, meaning they are known to cause cancer in humans.
Dr. Kris Hansen said “I am not a toxicologist or a physician or an epidemiologist. And so my knowledge comes just from a lot of exposure and a lot of reading and a lot of listening to smart people.” She continued, “While it's true that there may be some members of the PFAS class that are not toxic. There certainly are some classes — compounds that are toxic — and the vast majority have not been studied.”
She continued, “Of those, say 15 that we've studied extensively, have a number of health effects related to the immune system, suppressing an immune response, especially in children. Thyroid disease, heart disease, via high cholesterol, kidney and testicular cancer issues associated with it's the GI Tract.”
“The second is because these compounds are ubiquitous. We're not really concerned about the health effects on a healthy, middle-aged person. We're talking about the health effects on pregnant people, infants, people with cancer, elderly people, and people with autoimmune diseases.”
Are municipal waste biosolids safe to use as fertilizer?
Answer: Yes, as long as the biosolids are not contaminated with industrial waste.
Our panelist stressed that industrial waste is a major source of contamination, sometimes with levels of PFAS that are several magnitudes, 100 and 1000 times higher than in typical municipal waste. The panelists stressed that they were most concerned with industrial waste and industrial contamination.
Dr. Ian Pepper has conducted long-term soil studies on agricultural fields fertilized with biosolids. He looked at the amount of PFAS in the soils (incidence) and if the PFAS can leach or be absorbed into the crops on the field (mobility). Dr. Pepper said, “We looked at incidence and mobility of PFAS at land application sites, known land application sites where we had the life history of biosolid loadings. Going back to 1984, we took copious soil samples, looked at incidents and mobility, found that incidence and mobility were both low.”
Chris Peot said, ”You get as much PFAS from rainfall on a farm field in Maryland as you would from our biosolids. So it's just further evidence that it's [PFAS] ubiquitous in our society.” He continued, “There's a couple of studies out there that I have showing that household dust has 10 times the PFAS than [the biosolid fertilizer product we produce from municipal waste].”
What should we do now?
Answer: Stop PFAS at the source. All of our panelists agreed that PFAS production needs to be regulated immediately, and the focus should be on the companies that continue to make PFAS.
Dr. Bryn Nelson said, “There's been a lack of attention to upstream industrial sources. News features often start in the middle of the story as if PFAS just sort of magically fell from the sky into wastewater streams. We know that's not the case.”
Dr. Kris Hansen said ”as someone who lives very close to a fluorochemical manufacturing facility, and seeing the compounds that are manufactured there show up in the fields and on the snow, and everywhere else we just need to stop producing these chemicals and stop using them in the products that that we surround ourselves with. That's the biggest message that I have is source control.”
Chris Peot added,” We could insist on labeling requirements so that people understand what they're buying.”
If consumers knew the PFAS levels in each product they’re buying, then they might be less inclined to purchase them. Consider several years ago when BPA, or bisphenol A, a chemical used to make polycarbonate plastic, was found to have negative health effects because the chemical would leach into the water stored in that plastic bottle. Now, store shelves are filled with reusable water bottles with stickers showing that they are BPA free.
Ultimately, we learned that the problem isn’t the biosolids themselves. Nor is it a lack of due diligence from municipal utilities in following regulations and navigating the best treatment. Instead, the risk lies with industrial waste sources. We do want to avoid using biosolids produced from industrially contaminated wastewater streams. And, the alternatives for sludge disposal are just as bad. Those options are: burning it, which blasts toxins into the air; or, burying it, which occupies limited space in landfills and adds to the already toxic leachate. However, recovering valuable nutrients like phosphorus and nitrogen from municipal wastewater sludge for agricultural use has a long history of safe and beneficial application.
Ending PFAS/PFOS production — and strictly regulating and monitoring industrial wastewater — is the only way to safeguard our health and food system.
About the Panelists
Kris Hansen, Savanna Science Consulting & former 3M scientist
Kris is an independent consultant at Savanna Science specializing in industrial pollutants in the environment as well as industry's tactics to manufacture doubt about the state of their knowledge. Kris was formerly technical lead in method development and characterization of 3M's PFAS chemicals in the environment. Her experiences at 3M were documented by journalist Sharon Lerner in May 2024 in The New Yorker and on ProPublica.
Bryn Nelson, Science Writer & Author
Bryn is the author of "Flush: The Remarkable Science of an Unlikely Treasure," about the science and hidden value of poop. After receiving his doctorate in microbiology from the University of Washington, he transitioned to science writing and has been a science, medical and environmental journalist for the past 25 years. Nelson has written for Newsday, The New York Times, Scientific American, Nature, The BMJ, WIRED, and many other publications. He has visited numerous wastewater treatment plants while on vacation, and calls Seattle home.
Chris Peot, Director of Resource Recovery, DC Water
Chris is an environmental engineer with more than twenty five years experience in wastewater treatment, residuals reuse, and recycling. His work experience includes operations manager for a 1200 ton/day, implementation of the Bloom product and marketing plan, development for new biosolids reuse options, development of a nationally recognized research program, design/construction inspection/permitting work, and development of an award winning EMS program. In recent years, Chris has also focused on green energy development, carbon footprint modeling, and renewable energy credits.
Ian Pepper, Professor of Microbiology, University of Arizona
Ian is a Regents Professor at the University of Arizona. He is also Director of the University of Arizona Water & Environmental Technology Center (WET), and Director of the Water and Energy Sustainable Technology Center (WEST). He is an environmental microbiologist whose research has focused on soil and water quality and land application of biosolids. He is the author or co-author of nine textbooks; 40 book chapters; and over 250 peer-review journal articles.
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