A new study led by the North Carolina State University has found that alligators in the Cape Fear River had elevated levels of 14 different per- and polyfluoroalkyl (PFAS) chemicals in their blood serum, together with genetic and clinical indicators of immune system disruption. These findings add to the growing body of evidence that exposure to PFAS can have adverse effects on immunity.
The scientists collected blood samples and performed health evaluations on 49 alligators living along the Cape Fear River between 2018 and 2019, and compared the results to a reference population of 26 alligators from Lake Waccamaw, located in the adjoining Lumber River basin.
“We looked at 23 different PFAS and saw clear differences between both types and levels of PFAS in the two populations,” said study senior author Scott Belcher, an associate professor of Biology at NC State University. “We detected an average of ten different PFAS in the Cape Fear River samples, compared to an average of five different PFAS in the Lake Waccamaw population.”
“Additionally, blood concentrations of fluoroethers such as Nafion byproduct 2 were present at higher concentrations in alligators from the Cape Fear River basin, whereas these levels were much lower – or not detected – in alligators from Lake Waccamaw. Our data showed that as we moved downstream from Wilmington to Bald Head Island, overall PFAS concentrations decreased.”
However, the most surprising finding was that alligators from the Cape Fear River had several unhealed or infected lesions. “Alligators rarely suffer from infections,” Professor Belcher explained. “They do get wounds, but they normally heal quickly. Seeing infected lesions that weren’t healing properly was concerning and led us to look more closely at the connections between PFAS exposure and changes in the immune systems of the alligators.”
A qRT-PCR genetic analysis revealed significantly high levels of interferon-alpha (INF-α) responsive genes in these alligators – nearly 400 times higher than those of the Lake Waccamaw alligators that had lower PFAS concentrations in their blood serum. These genes are involved in stimulating immune responses, particularly in relation to viral infections. According to the researchers, in humans, chronic high expression of these genes is an indication of autoimmune diseases, such as lupus. “When we see elevated expression of INF-α in these alligators, then, it tells us that something in these alligators’ immune responses is being disrupted,” Professor Belcher said.
“Alligators are a sentinel species – harbingers of dangers to human health. Seeing these associations between PFAS exposure and disrupted immune function in the Cape Fear River alligators supports connections between adverse human and animal health effects and PFAS exposure,” he concluded.
The study is published in the journal Frontiers in Toxicology.
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