Dive Brief:

• U.S. landfills containing municipal solid waste are releasing certain kinds of per- and polyfluoroalkyl substances into the air in amounts comparable to the release of PFAS chemicals via liquid, or leachate, according to a study published in Environmental Science & Technology.
• The study, released in November, is the most comprehensive look yet at real-world PFAS emissions stemming from landfill gas. The study's authors sampled 30 municipal solid waste landfills across 17 states in a range of climates to understand on a deeper level how airborne PFAS behaves in landfills exposed to different rainfall patterns, waste compositions and other variables. 
• More research could help determine the persistence of airborne PFAS downwind of landfills. That could in turn inform public health concerns about exposure to the potentially toxic chemicals for landfill workers and the general public.

Dive Insight:

There are a variety of pathways by which PFAS find their way into and out of a landfill. Scientists have developed more than 4,000 variations of the class of chemicals used in an array of manufacturing processes, including in the production of consumer goods. Those goods break down in a landfill over time, releasing toxic chemicals like PFAS as they degrade. 

Researchers have found that certain kinds of PFAS chemicals are drawn to water in a landfill and become part of the facility's leachate. That leachate is usually either treated on site or sent to a wastewater treatment plant for processing, but most facilities aren’t yet able to destroy PFAS in the liquid. Current research suggests that roughly 600 kilograms of PFAS chemicals are released through landfill leachate annually in the U.S., and may cause public health issues if they enter drinking water at significant concentrations.

Landfills are releasing an estimated 836 kilograms of PFAS annually through their gas, the new study determined. The kinds of PFAS chemicals researchers found in landfill gas commonly stem from grease-proofing agents used in pizza boxes and other food packaging. Those chemicals, known as fluorotelomer alcohols, can transform into PFOA in the environment. 

PFOA is a form of PFAS known for decades to be toxic to human health. It was phased out as a chemical commonly used in manufacturing, but continues to show up in the environment because it can take hundreds of years to break down. Last year, the EPA designated PFOA and a similar form of PFAS as hazardous substances and published drinking water limits for the chemicals for the first time; the latter move has been limited slightly by the Trump administration. Those rules are now forcing facility operators to find ways to mitigate and destroy the chemicals where possible.

The new study shows the difficulty of finding and mitigating pathways through which the chemicals can find their way into the environment, said lead author Florentino De la Cruz, an assistant professor at the University of North Florida. 

The possibility of destroying or sequestering these compounds, meanwhile, continues to be an emerging field of study. The U.S. Department of Defense is preparing to present the results of 10 pilot projects demonstrating various destruction technologies for the chemicals, with participating companies hinting at positive results. The department has also partnered with the U.S. EPA to test incineration destruction capabilities at multiple sites. A test with Clean Harbors' hazardous waste incinerator returned promising results, while another pilot with a Reworld municipal solid waste incinerator remains under study.

Those studies are investigating a potential pathway to destroy PFAS-contaminated substances, while the new landfill study is focused on incidental releases.

It’s unclear how far airborne PFAS chemicals travel after they exit the landfill. Researchers found some variability among the landfills’ releases that they're hoping to better understand. De la Cruz said several new studies grew out of this survey, including a look at whether existing landfill gas collection and control systems destroy or alter PFAS chemicals. Such systems may include flaring or energy generation, either through the production of pipeline-quality natural gas or electricity.

The latest study included collaborators from the University of North Florida, North Carolina State University and Oregon State University.