Alligators exposed to ‘forever chemicals’ show autoimmune impacts: study

Alligators exposed to “forever chemicals” in North Carolina’s Cape Fear River may be experiencing adverse clinical and autoimmune effects, a new study has found. 

In addition to showing genetic indicators for immune system impacts, the animals had many unhealed or infected lesions, according to the study, published on Thursday in Frontiers in Toxicology. 

“Alligators rarely suffer from infections,” Scott Belcher, an associate professor of biology at North Carolina State University, said in a statement. 

“They do get wounds, but they normally heal quickly,” he continued.

From 2018 to 2019, Belcher and his colleagues took blood samples and conducted health evaluations on 49 alligators living along the Cape Fear River. 

They found that the animals had elevated levels of 14 different types of so-called forever chemicals, also known as per- and polyfluoroalkyl substances (PFAS).

There are thousands of types of PFAS — artificial compounds that can persist for decades in the environment and are linked to many illnesses, such as thyroid disease, testicular cancer and kidney cancer. 

Notorious for their presence in jet fuel, firefighting foam and industrial discharge, PFAS are also key ingredients in a variety of household items, such as non-stick pans, cosmetics and waterproof apparel. 

The Cape Fear River basin has long been contaminated by PFAS, as multiple industries have discharged the substances into the waterway for years. 

The basin, located in central and coastal North Carolina, covers more than 9,300 square miles of waterways that service about 5.2 million residents, according to the study. 

Upstream contamination in the Cape Fear largely has come from fluorochemical production, manufacturing, wastewater treatment discharges and the use of firefighting foams, the authors noted. 

As Belcher and his team studied the alligators that inhabit the river, they said they detected an average of 10 different types of PFAS in the animals’ blood samples. 

They compared these findings to a reference population of 26 alligators from Lake Waccamaw, in the adjoining Lumber River basin, where they observed an average of five different types of PFAS, according to the study. 

As they moved downstream from Wilmington — where much of the industrial sources are situated – the researchers said they saw that overall PFAS concentrations decreased.

But their most unusual observation, according to the authors, was the number of unhealed lesions on the alligators that they observed. 

“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,” Belcher said.

The scientists then conducted a genetic analysis, which revealed elevated levels of genes that are responsive to an immune protein called interferon-alpha. These levels were 400 times higher than those of the Lake Waccamaw alligators, according to the study. 

The set of interferon-alpha responsive genes that the researchers identified in the alligators are typically involved in viral infections, Belcher explained. In humans, high expression of these genes is an important indicator of autoimmune diseases, such as lupus, he continued. 

Already, some PFAS exposures in humans have been connected to chronic autoimmune disorders like ulcerative colitis and thyroid disease, Belcher noted. 

Equipped with multiple years of sampling data on the alligators, the researchers said they are in a good position to continue tracking PFAS exposure and health changes in both individual alligators and larger populations 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,” he added.