A recent study published in Environmental Toxicology and Chemistry by Oxford University Press highlights a surprising resilience among tree swallow populations in the United States, despite high levels of exposure to “forever” chemicals. These per- and polyfluoroalkyl substances (PFAS), known for their persistence in the environment, have not adversely affected the reproductive health of these birds, according to the research findings.
Manufactured materials containing PFAS are a global environmental concern. These chemicals enter ecosystems through discharges from manufacturing plants, firefighting activities, and wastewater treatment plants. Common consumer products, such as stain-resistant fabrics, nonstick cookware, and food packaging, also contribute to their prevalence. Despite their durability and resistance to environmental breakdown, the ecological impact of these substances remains largely unexplored.
Understanding the Impact of ‘Forever’ Chemicals
PFAS have been detected in various environmental components, including soil, water, plants, animals, and humans across all continents. While these chemicals are linked to serious health issues like cancers and reproductive problems in humans, their effects on wildlife are not well understood. Laboratory research has explored chemical exposure in animals, but the impact on wild populations is less clear due to the scarcity of field studies, which are often costly and time-consuming.
In this study, researchers assessed chemical levels in the tissues and diet of tree swallows, a migratory bird native to North America, across sites with varying contamination histories. The study aimed to determine the relationship between chemical exposure and the birds’ reproductive success.
Field Study Insights
The research was conducted at several military bases and other sites, including Willow Grove, Pennsylvania; Lakehurst, New Jersey; Camp Springs, Maryland; Chesapeake Beach, Maryland; Laurel, Maryland; Ashumet Pond, Massachusetts; Lake Elmo, Minnesota; Grey Cloud Island, Minnesota; Gibson City, Illinois; and Scanlon, Minnesota. The findings revealed higher concentrations of PFAS at sites treated with firefighting foams and those near urban areas.
Particularly high concentrations of the forever chemical perfluorohexane sulfonate were found near Cottage Grove, Minnesota, due to manufacturing plant residues and waste disposal, as well as other household and industrial sources from the Minneapolis/St. Paul metropolitan area.
Resilience in the Face of Contamination
Despite varying levels of exposure to these chemicals, the study found no statistically significant association between chemical exposure and reproductive outcomes, such as hatching success or the ability of chicks to reach fledging. The health of the bird chicks appeared unaffected by the levels of chemical exposure, suggesting a remarkable resilience among these populations.
“Tree swallows, despite high exposure to PFAS, showed no adverse reproductive effects, highlighting a potential resilience or adaptability in these birds,” the study concludes.
The paper, titled “Tree Swallows as Indicators of Per- and Polyfluoroalkyl Substance (PFAS) Exposure and Effects at Selected Department of Defense Sites along the East Coast and at Sites with Other PFAS Sources in the Upper Midwest, USA,” is available for further reading at https://doi.org/10.1093/etojnl/vgaf207.
Implications and Future Research
The findings offer a glimmer of hope in understanding the ecological impact of PFAS, suggesting that some wildlife may possess mechanisms to withstand chemical exposure. However, the study underscores the need for further research to explore the long-term effects of these substances on different species and ecosystems.
Christine M. Custer, a leading researcher from the US Geological Survey’s Upper Midwest Environmental Sciences Center, emphasizes the importance of continued investigation into the ecological effects of PFAS. “While this study provides valuable insights, it is crucial to expand our understanding of how these chemicals affect various species over time,” she notes.
As the scientific community continues to unravel the mysteries surrounding PFAS, the resilience of tree swallows offers a unique perspective on the potential adaptability of wildlife in polluted environments. Future studies may uncover more about the mechanisms that enable certain species to thrive amidst chemical challenges, ultimately guiding conservation efforts and policy decisions.
