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Tree Swallows Near U.S. Military Bases Carry Alarming Levels of Toxic 'Forever Chemicals'
16 Oct
Summary
- Tree swallows near U.S. military bases have 40 times higher PFAS levels than other environments
- PFAS chemicals can bioaccumulate up the food chain, impacting wildlife and humans
- Experts warn of widespread PFAS contamination from military use of firefighting foam

According to a study published in 2023, tree swallows living near U.S. military bases are carrying significantly higher levels of PFAS chemicals compared to those in other environments. PFAS, also known as 'forever chemicals', are a group of synthetic compounds that have been linked to a range of health issues, including cancer.
The researchers, led by the U.S. Geological Survey, tested eggs, nestlings, and the insects consumed by tree swallows at 10 locations across the Mid-Atlantic and Upper Midwest regions. They found that the total PFAS levels in samples from the military sites were 40 times higher than in other areas.
Experts say this is concerning as PFAS can bioaccumulate, meaning they can build up in the bodies of living organisms and move up the food chain. This raises the risk of exposure for wildlife and potentially for humans who consume contaminated food sources.
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"PFAS exposure has many different health risks in people. PFAS exposure has been linked to different types of cancer, high cholesterol, reduced immune system functions, low birth weight, liver damage, thyroid disease, and other health effects," warned Jamie DeWitt, director of the Environmental Health Sciences Center at Oregon State University.
The high PFAS levels in the tree swallows are largely attributed to the use of aqueous film-forming foam (AFFF) at military bases, which contains high concentrations of these chemicals. The foam can leach into the surrounding soil and water, contaminating the environment.
While the study did not find immediate impacts on the health of the tree swallows, experts caution that the widespread presence of PFAS in the environment is a serious concern that requires urgent action to address the contamination at its source.