Alligators along North Carolina's Cape Fear River have high blood levels of 14 toxic chemicals, along with signs of immune system damage, new research shows.
The study of levels of per- and polyfluoroalkyls (PFAS) in the reptiles' blood adds to concerns that the chemicals may cause genetic and immune system harm. Alligators are a sentinel species, providing advance warning about environmental risks to humans.
"Alligators rarely suffer from infections," said Scott Belcher, associate professor of biology at North Carolina State University.
"They do get wounds, but they normally heal quickly," he said in a university news release. "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."
PFAS are used in many everyday products. They keep food from sticking to cookware, make fabrics resistant to stains and improve effectiveness of firefighting foam, according to the U.S. National Institute of Environmental Health Sciences.
Belcher led the team that collected blood samples and did health evaluations on 49 alligators living along the Cape Fear River between 2018 and 2019.
They were compared to 26 alligators from Lake Waccamaw, about 30 miles away in the adjoining Lumber River basin in North Carolina.
The researchers looked at 23 PFAS and saw clear differences between types and levels in the two populations.
"We detected an average of 10 different PFAS in the Cape Fear River samples, compared to an average of five different PFAS in the Lake Waccamaw population," Belcher said.
In addition, blood levels of fluoroethers were higher in Cape Fear River alligators and much lower -- or not detected -- in the Lake Waccamaw gators.
Researchers said it was unusual to see the Cape Fear alligators with a number of unhealed or infected lesions.
A genetic analysis revealed that they had significantly higher levels of interferon-alpha (INF-α) responsive genes — 400 times higher than those of the Lake Waccamaw alligators, which also had much lower PFAS blood levels.
INF-α is a protein involved in stimulating immune response.
"The set of INF-α responsive genes we analyzed are normally involved with viral infections," Belcher said. "In humans, chronic [or long-term] high expression of this set of genes is an important indicator of autoimmune diseases, especially lupus."
PFAS exposure in humans is also linked with chronic autoimmune disorders such as ulcerative colitis and thyroid disease, he pointed out.
"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," Belcher said.
His team has collected data on the same alligators each year for five years and plan to continue monitoring their PFAS exposure and health in both habitats.
"Alligators are a sentinel species -- harbingers of dangers to human health," Belcher said. "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."
The findings were published Oct. 20 in Frontiers in Toxicology.
The U.S. Environmental Protection Agency has more on PFAS.
SOURCE: North Carolina State University, news release, Oct. 20, 2022