Perfluorinated compounds found in African crocodiles, American alligators

August 25, 2016

American alligators and South African crocodiles populate waterways a third of the globe apart, and yet both have detectable levels of long-lived industrial and household compounds for nonstick coatings in their blood, according to two studies from researchers at the Hollings Marine Laboratory in Charleston, South Carolina, and its affiliated institutions, which include the National Institute of Standards and Technology.

Production of some compounds in this family of environmentally persistent chemicals--associated with liver toxicity, reduced fertility and a variety of other health problems in studies of people and animals--has been phased out in the United States and many other nations. Yet all blood plasma samples drawn from 125 American alligators across 12 sites in Florida and South Carolina contained at least six of the 15 perfluorinated alkyl acids (PFAAs) that were tracked in the alligator study.

The two studies are first-of-their-kind examinations of PFAA levels in "sentinel" reptile species, especially useful for investigating the impacts of long-lived chemicals in the environment. PFAAs have been used in products that include water-repellent clothes, stain repellents, waxes, nonstick pans and fire-suppressing foams.

In alligators, plasma levels of perfluorooctane sulfonate (PFOS) ranged from 1,360 to 452,000 parts per trillion. In May 2016, the Environmental Protection Agency issued a drinking-water health advisory for PFOS and another PFAA, recommending a maximum exposure level of 70 parts per trillion for one of the PFAAs or the sum of the two. High PFOS levels reported for alligators at several sites may suggest the need to test drinking water for contamination at those locations, according to the researchers.

In a separate study, researchers report that all samples drawn from 45 crocodiles at five sites in and around South Africa's Kruger National Park contained detectable levels of four PFAAs, often in different combinations with other of the 15 fluorinated organic compounds tracked. Present in all plasma samples, PFOS levels ranged from 776 to 118,000 parts per trillion.

"Alligators and crocodiles play a dominant role in their ecosystems," said Jacqueline Bangma, of the Medical University of South Carolina in Charleston. "Similar to humans, they are long-lived top predators. They stay in a select territory--waterways where runoff from human activities accumulates-- and their PFAA burden increases through the consumption of fish."

To date, field studies of PFAA levels and health effects in reptiles have been few, focusing mostly on sea turtles. Across studies of animals--from rats to frogs to marine mammals--plasma levels, time required to eliminate PFAAs from the body, and health effects vary greatly, making it difficult to extrapolate from one species to another.

The landmark studies were initiated by the Hollings Marine Laboratory, a partnership including NIST, NOAA's National Ocean Service, the South Carolina Department of Natural Resources, the College of Charleston, and the Medical University of South Carolina. Plans are to continue PFAA monitoring on both continents, according to NIST research chemist Jessica Reiner.

Both studies identified "hot spots," where PFAA levels were significantly higher than in animals tested at other sites, an indication that the contaminants were emitted by a nearby source. In the U.S. study, median plasma levels of certain PFAAs were highest in alligators on Kiawah Island, an Atlantic Ocean barrier island southwest of Charleston, South Carolina, and on Merritt Island in Florida.

Past use of PFAA-containing foams, such as those employed in firefighting training, may account for the higher levels, the researchers suggest. High environmental concentrations have been reported at fire-training sites and at manufacturing plants.

In contrast, alligators at two sites in the Florida Everglades exhibited some of the lowest levels of the two "highest burden" PFAAs reported across all adult alligators sampled in the U.S. study. The result was somewhat unexpected, Reiner said, because Everglade's alligators have been reported to have some of the highest levels of mercury, a toxic heavy metal, among Florida alligators.

Among the South African crocodiles tested, PFAA levels were highest for animals tested from Flag Boshielo Dam, a reservoir on the Oliphants River, just upstream from Kruger National Park.

Among the American alligators studied, some PFAA levels tended to be higher among males, regardless of locations. Levels also tended to increase with age, as determined by snout length. Age- and sex-related associations with PFAA levels were not found in the crocodiles sampled.
Articles: I. Christie, J.L. Reiner, J.A. Bowden, H. Botha, T.M. Cantu, D. Govender, M.P. Guillettee, R.H. Lowers, W.J. Luus-Powell, D. Pienaar, W.J. Smit and L.J. Guillette Jr. Perfluorinated alkyl acids in the plasma of South African crocodiles (Crocodylus niloticus). Chemosphere. Published: July 2016. DOI: 10.1016/j.chemosphere.2016.03.072.

J.T. Bangma, J.A. Bowden, A.M. Brunell, I. Christie, B. Finnell, M.P. Guillette, M. Jones, R.H. Lowers, T.R. Rainwater, J.L. Reiner, P.M. Wilkinson and L.J. Guillette, Jr. Perfluorinated alkyl acids in plasma of American alligators (Alligator mississippiensis) from Florida and South Carolina. Environmental Toxicology and Chemistry. Accepted manuscript online: August 20, 2016. doi:10.1002/etc.3600

National Institute of Standards and Technology (NIST)

Related Alligators Articles from Brightsurf:

Paleontologists identify new species of mosasaur
A new species of an ancient marine reptile evolved to strike terror into the hearts of the normally safe, fast-swimming fish has been identified by a team of University of Alberta researchers, shedding light on what it took to survive in highly competitive ecosystems.

New study confirms the power of Deinosuchus and its 'teeth the size of bananas'
A new study, revisiting fossil specimens from the enormous crocodylian, Deinosuchus, has confirmed that the beast had teeth ''the size of bananas'', capable to take down even the very largest of dinosaurs.

Palaeontology: Ancient footprints may belong to two-legged crocodile, not giant pterosaur
The discovery of large well-preserved footprints belonging to an ancestor of modern-day crocodiles from the Lower Cretaceous Jinju Formation of South Korea is reported this week in Scientific Reports.

Extinct giant turtle had horned shell of up to three meters
Paleobiologists from the University of Zurich have discovered exceptional specimens in Venezuela and Colombia of an extinct giant freshwater turtle called Stupendemys.

Are sinking soils in the Everglades related to climate change?
Soils releasing carbon as gas lead to challenges on valuable farmland

What did ancient crocodiles eat? Study says as much as a snout can grab
To study the diet of ancient crocodiles, two researchers--one from the University of Tennessee, Knoxville, and one from Stony Brook University--combined mathematical analyses of the animals' shapes, surveys of modern crocodiles' diet, modeling methods for reconstructing the diet of fossil groups, and forensic-style interpretations of damaged bones from the distant past.

Prehistoric AC
Tyrannosaurus rex, one of the largest meat-eating dinosaurs on the planet, had an air conditioner in its head, suggest scientists from the University of Missouri, Ohio University and University of Florida, while challenging over a century of previous beliefs.

U of Guelph researchers learn how low oxygen builds a bigger, stronger alligator heart
University of Guelph researchers are beginning to understand why some alligators develop stronger hearts after enduring low oxygen during early development in the egg.

Hear them roar: How humans and chickadees understand each other
Is there something universal about the sounds we make that allows vocal learners -- like songbirds -- to figure out how we're feeling?

Study: Infamous 'death roll' almost universal among crocodile species
The iconic 'death roll' of alligators and crocodiles may be more common among species than previously believed, according to a new study published in Ethology, Ecology & Evolution and coauthored by a researcher at the University of Tennessee, Knoxville.

Read More: Alligators News and Alligators Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to