As states work to limit the use of PFAS, one path for their spread is often overlooked: incineration of consumer waste, such as clothing, textiles, food packaging, paints, and electronics.
Regulatory agencies are paying some attention to the PFAS (per-and polyfluoroalkyl substances) waste stream, such as contaminated leachate from landfills. However, about 12% of the U.S. waste stream goes to the country’s 75 aging municipal solid waste incinerators, with minimal research on likely byproducts of burning PFAS-tainted trash.
Now “PFAS in air emissions and incineration are becoming more of a focus,” Lydia Jahl, a science and policy associate for the Green Science Policy Institute, told EHN.
Ingesting contaminated water and food pose the highest known risk for PFAS exposure, which is linked to multiple negative health outcomes including some cancers, reproductive problems, and birth defects. Airborne emissions from incinerators could be spreading PFAS significant distances, researchers warn, increasing the risk of contaminated water and soil downwind of facilities.
Research in Europe suggests waste incinerators are contributing to plumes of airborne PFAS pollution, but U.S. regulators are not yet tracking this threat.
Municipal waste incinerators only report hazardous air pollutants — like dioxin, mercury, and lead — to the U.S. Environmental Protection Agency (EPA) every three years, and PFAS compounds are not yet listed in this category. Some PFAS were recently added to the agency’s Toxic Release Inventory, which mandates annual reporting of how toxic compounds are managed, but researchers have noted that the initial PFAS reporting likely underestimates airborne emissions.
Dubbed “forever chemicals,” PFAS are notoriously long-lived due to strong carbon-fluorine bonds. EPA’s research suggests that these “chemicals are not really broken down at normal incinerator temperatures,” Tim Schroeder, a geologist at Bennington College in Vermont who has studied the movement of PFAS through local ecosystems, told EHN.
“Much is currently unknown” about how PFAS compounds behave during incineration, a spokesperson for the EPA’s Office of Research and Development wrote in an email to EHN, explaining that PFAS molecules at lower temperatures may not break apart or may decompose partially and recombine to form new PFAS.
A team of international scientists reached a similar conclusion in a recent study of fluoropolymers, a sub-class of PFAS, writing that “it is currently unclear whether typical municipal solid waste incinerators can safely destroy fluoropolymers without emissions of harmful PFAS and other problematic substances.”
The Solid Waste Association of North America has more confidence that incinerators “designed to manage non-hazardous waste are destroying most of the PFAS in municipal solid waste” based on the potential temperatures they can achieve, Jeremy O’Brien, SWANA’s director of applied research, told EHN. That premise, however, is not based on emissions testing or even continuous temperature monitoring at U.S. incinerators. “Further testing of actual emissions may be useful to better quantify potential health risks,” he added.
EPA has no field testing underway to determine what kinds or levels of PFAS may be emitted through municipal waste incineration, and “no timeline for testing,” but a spokesperson wrote that characterizing these emissions “remains an EPA priority.” Meanwhile, Europe has begun assessing potential public health and environmental risks from PFAS exposure linked to waste incineration.
Europe Finds “Alarming” Levels of PFAS Downwind of Incinerators
Testing incinerator emissions is complicated by the daunting number of PFAS compounds, upwards of 9,000. In Europe, researchers used bioassays [which detect compounds in living tissues or organs] to circumvent the challenges of chemically assessing stack emissions for all the potential PFAS in a study completed for Zero Waste Europe. Funded by the European Union, the research involved testing for PFAS and other pollutants in animal and plant cells at sites downwind of three waste incinerators.
Released in January, the studies found high levels of PFAS in chicken eggs and mosses near a waste incinerator in the Czech Republic. Downwind of an incinerator in Madrid, Spain, researcher Abel Arkenbout, a Dutch toxicologist from the ToxicoWatch Foundation, reported “alarming” PFAS levels in pine needles, 10 times greater than the reference sample.
Based on these findings and review of some not-yet-published studies, Arkenbout told EHN via email, “our hypothesis is that PFAS cannot be destroyed completely at temperatures used in Waste-to-Energy [municipal waste] incinerators.”
This biomonitoring work was the first such study done in Europe, but Xenia Trier, a chemicals, environment and human health expert with the Air Pollution, Environment and Health branch of the European Environment Agency, wrote EHN that “emissions of PFAS from waste facilities are on the radar in Europe, and there will likely be more research studies on this through national and EU funding.”
Airborne PFAS
If the European hypothesis that incinerators are emitting PFAS proves true, where do those molecules go?
Tracking the movement of PFAS emitted from industrial or incinerator stacks is a more “three-dimensional” challenge than following it downstream in a river flowing one way with two banks, explained Ralph Mead, a chemistry professor at University of North Carolina Wilmington (UNCW) and co-author of a recent study tracking how PFAS compounds settle out of the atmosphere.
The path and distance that airborne molecules travel depends on temperature, humidity, and wind speed, and when the compounds shift from a gas to a particle.
In a study done in Vermont, Schroeder of Bennington College found a downwind plume of PFAS dispersal that extended over roughly 125 square miles, including some sites 2,000 feet higher in elevation than the factory source. While both that study and the UNCW one assessed PFAS dispersion from manufacturing facilities, “it’s a logical extension,” Schroeder said, to assume similar transport patterns from incinerator stacks.
The North Carolina facility Mead studied is a Chemours (formerly DuPont) plant that produces a newer PFAS compound known as GenX, the chemical HFPO-DA, marketed as a safer replacement (despite old and recent research confirming that it poses similar health and environmental threats). EPA modeling there showed that 97.4% of the GenX emitted from the site traveled more than 93 miles.
‘Legacy’ forms of PFAS (manufactured prior to 2015) have been found at both poles due to atmospheric transport, and the GenX replacement — which EPA describes as “more mobile” and equally persistent — is now moving around the globe, even turning up in Arctic waters.
Atmospheric deposition is unquestionably one of the routes of PFAS contamination, Mead said, and it’s gaining attention. “From a scientific perspective, it’s fascinating. From an environmental health and human health perspective, it’s pretty scary.”
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