What exactly is in your water? Just ask a crocodile
August 26, 2016
Although oceans apart, African crocodiles and American alligators now have one more thing in common: they’ve both tested positive for levels of long-lasting industrial and household compounds in their blood. A recent study, reported in EurekAlert, found that 125 American alligators’ blood plasma contained at least six of the same 15 perlfluorinated alkyl acids (PFAAs).
A crocodile from Flag Boshielo Dam, upstream from South Africa's Kruger National Park. Photo credit: John Bowden/HML
PFAAs are part of a group of chemicals that live-long in nature, they’ve been associated with liver toxicity, reduced fertility and a host of other problems in both humans and animals. The chemicals can be found in water-repellent clothes, stain repellents, waxes and fire-suppressant foams. Their use been phased out in many developed countries, including in the US, but the study suggests they are still out there.
Their presence in the blood of alligators and crocs is disconcerting; the species are “sentinel” reptiles, similar to the ill-fated canary in the mine, they can give advanced warning of dangers in an ecosystem. By studying them the long lasting effects of environmental contamination can be revealed.
According to the study, alligators showed plasma levels of perfluoroctane sulfonate (PFOS) ranging from 1,360 to 452,000 parts per trillion. In May this year, the US’ Environmental Protection Agency declared a drinking-water health advisory, recommending that humans be exposed to a maximum of 70 parts per trillion for just one of the PFAAs or the sum of two.
The researchers suggest, due to these potentially massive levels of PFOS found in alligators, the drinking water may need testing.
Similarly in South Africa, 45 crocodiles from the iconic Kruger National Park were found with levels of four different PFAAs in their blood. The levels of PFOS ranged from 776 to 118,000 parts per trillion.
"Alligators and crocodiles play a dominant role in their ecosystems," Jacqueline Bangma, of the Medical University of South Carolina in Charleston, told EurekAlert. "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."
The researchers also identified potential “hot spots” of contamination, where the use of PFAAs were high and emitted from a nearby source in the past. In the US, alligators from Kiawah Island, South Carolina and on Merritt Island in Florida had the highest concentrations. In South Africa, crocs from Flag Boshielo Dam tested highest, the reservoir lies upstream from Kruger.
The study gives an insight into the longevity of potentially harmful chemicals, although our use of them may stop they can linger in the natural environment for a long, long time. However, it is difficult to clearly note any level of danger from the study, as the effect of high concentrations of PFAAs is not uniform across species. The study remains as a warning sign; our water may not be as clean as we think, just ask your nearest alligator or croc.
This study was conducted by the Hollings Marine Laboratory.