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• Posted June 21, 2023

PFAS 'Forever Chemicals' Found in Blood of Pet Dogs, Horses

New research on horses and dogs found elevated levels of PFAS “forever chemicals,” establishing horses as sentinel species.

Sentinel species provide advance warning of a danger to people.

The work also advanced knowledge about PFAS exposure and liver and kidney function in these animals. PFAS stands for per-and polyfluoroalkyl substances, a group of chemicals used in plastics and grease- and water-resistant materials. They're a health concern because they don't break down in the environment and are found in soil and water sources.

“Horses have not previously been used to monitor PFAS exposure,” said first author Kylie Rock, a postdoctoral researcher at North Carolina State University. “But they may provide critical information about routes of exposure from the outdoor environment when they reside in close proximity to known contamination sources.”

In the new study, researchers detected elevated PFAS levels in the blood of 31 pet dogs and 32 horses from Grays Creek, N.C., including dogs that drank only bottled water.

The study was conducted at the request of residents concerned about their pets' well-being. Their homes used wells that state inspectors had determined to contain PFAS.

Animals each had a general veterinary health check, as well as blood tests to screen for 33 PFAS chemicals. The chemicals were chosen based on compounds present in the Cape Fear River basin and the availability of standards to analyze them.

In all, 20 different PFAS were found in the animals. Each had at least one. And more than half had at least 12 of the 20 detected PFAS.

Found in the highest concentrations in dogs was PFOS, which was used for years in industrial and commercial products.

The perfluorosulfonic acid PFHxS was found in dogs, but not in horses. It's a surfactant used in consumer products and firefighting foams.

Some ether-containing PFAS including the toxic chemical HFPO-DA (also known as GenX), were detected only in animals that drank well water.

In dogs who drank well water, researchers found concentrations of two chemicals -- PFOS and PFHxS -- that were similar to those of children in the Wilmington GenX exposure study. (In 2017, residents of Wilmington, N.C., learned that GenX had been in their water supply for decades.)

The new study suggests that pet dogs could be an important indicator of exposure to PFAS.

Dogs who drank bottled water had different types of PFAS in their blood. These dogs had 16 of the 20 PFAS detected in the study.

Horses had higher concentrations of Nafion byproduct 2 (NBP2), suggesting that they may have been grazing on grass contaminated with PFAS.

The animals also had changes in diagnostic biomarkers used to assess liver and kidney dysfunction. In humans, these two organ systems are primary targets of PFAS toxicity.

“While the exposures that we found were generally low, we did see differences in concentration and composition for animals that live indoors versus outside,” said co-author Scott Belcher, an associate professor of biology at NC State.

“The fact that some of the concentrations in dogs are similar to those in children reinforces the fact that dogs are important in-home sentinels for these contaminants,” Belcher said in a university news release. “And the fact that PFAS is still present in animals that don't drink well water points to other sources of contamination within homes, such as household dust or food.”

Study findings were published June 21 in Environmental Science and Technology.

More information

The U.S. Centers for Disease Control and Prevention has more on PFAS.

SOURCE: North Carolina State University, news release, June 21, 2023