A research team out of NC State University is studying the effects of PFAS on the long-term health of alligators in the Cape Fear River Basin. The study is entering its sixth year and has collected samples from hundreds of alligators in North Carolina, including ones in Wilmington, Bald Head Island and Lake Waccamaw.
"The thing that will surprise people is alligators are no dummies," Scott Belcher, a researcher in the study and biology professor at NC State. "They recognize us now. And they're getting harder and harder to sample from because they see us coming and they know it's us."
For 5 years now, Belcher and a team of fellow researchers and undergraduates have been collecting blood samples and taking measurements of alligators in southeastern North Carolina — often taking samples from the same alligators.
"They can recognize my truck at Lake Waccamaw," he said.
To find and snag the alligators, the team will either drive or walk along the water. When they spot one, they cast a 8-10ft long surf rod aimed at the alligator's shoulder. They use a barbless hook so it could be easily removed from the skin. Once they hook an alligator, they reel it in close.
"It's sort of like fighting a a big fish," Belcher said.
Then while the alligator is still in the water, the team grabs a dog snare and loops it around its head and yank it up on shore. Someone else on the team quickly sits on the back of the alligator and tapes its mouth. From here, they quickly collect a blood sample, measure its length, and record its sex and any injuries they see. Belcher says their average time from catch to release is about 15 minutes.
The study started as a way to understand the long-term health effects of PFAS, per- and polyfluoroalkyl substances.
"When you think about PFAS, it's not one chemical. It's thousands of chemicals, and the vast majority know absolutely nothing about," Belcher said. "We don't know their identity. We don't know their toxicity.
PFAS chemicals are used in industrial manufacturing to make nonstick pans, raincoats, food wrappings, firefighting foams and all kinds of stain-proof coatings.
"So these are really resistance and that's why they're so attractive for so many," Belcher said. "Applications are because they are resistant to heat and mechanical breakdown, and they have a lot of usefulness."
What makes PFAS chemicals remarkably durable are their fluorinated carbon chains — a string of fluorine atoms paired with carbon, which together makes one of the strongest bonds in nature. Belcher says alligators make good research subjects because they have similar stages of development as humans.
Alligators live to between 60 and 70 years of age and they start reproducing around the age of 16. Because they live to a similar age as humans and live in the same areas, Belcher says they could serve as a record of how ingesting these chemicals affects the body over time.
"It's the idea of the canary in the coal mine," he said. "Many of our alligators were caught right in downtown Wilmington and at Greenfield Lake, so they are sharing the same environment. But they may also have certain characteristics that allow us to see any adverse effects that maybe we can't tease out from human populations."
The team compared two populations of alligators: one set within the Cape Fear River Basin and another at Lake Waccamaw, which is just outside the basin. The Cape Fear River Basin is known to have high levels of PFAS in its water because of years of pollution from manufacturers along the Cape Fear River — most notably the Chemours Plant in Fayetteville. Belcher’s team went in with a wholistic approach to see how PFAS affects alligators, but they quickly noticed that many of the alligators in the Cape Fear River Basin had long-lasting wounds. Belcher says that’s unusual for alligators.
"The first thing that we noticed was these unhealed lesions, which is very strange for alligators. Their immune system that responds to bacteria and viruses is really active, and that's why they can survive in these swampy environments."
Alligators, like humans, frequently get wounds, but their ability to heal goes beyond. Alligators typically heal quickly after, say, a limb is tore off. But Belcher and his team started seeing higher proportions of alligators with infected wounds in the Cape Fear River Basin. This prompted them to look into how PFAS affects the immune system, which shares many similarities with the our own immune system.
"Alligators and humans are far apart, but we share a lot of the same components of our immune system," he said.
After running some blood tests, the NC State team found that the alligators in the Cape Fear River Basin had a more active innate immune system.
The innate immune system is the immune response you are born with — it repairs cuts, protects against foreign invaders and kills bacteria. This is different than your adaptive immune system, which changes over time to combat new viruses — think of vaccines.
The researchers saw infected wounds because the innate immune response was running more often and more intensely. This type of deregulated immune response, in humans, contributes to a wide range of auto-immune diseases, like sepsis. This finding is consistent with previous studies on PFAS, which find the chemical class is linked to a slower immune system, liver damage, some cancers and decreased fertility.
Belcher and his team will resume their 6th year of field studies by mid-Spring.
