Researchers find organic pollutants not factor in turtle tumor disease

Jul 15, 2014
Persistent organic pollutants do not make Hawaiian green sea turtles more susceptible to the large tumors associated with fibropapillomastosis seen in this specimen. Credit: Keller/NIST

For nearly four decades, scientists have suspected that persistent organic pollutants (POPs) contributed to a green turtle's susceptibility to the virus that causes fibropapilomatosis (FP), a disease that forms large benign tumors that can inhibit the animal's sight, mobility and feeding ability. In a new study,* researchers from the Hollings Marine Laboratory (HML), a government-university partner facility in Charleston, S.C., and from university and federal collaborators in Hawaii demonstrated POPs are not, in fact, a co-factor linked to the increasing number of green sea turtles afflicted with FP.

POPs are a large group of man-made chemicals that, as their name indicates, persist in the environment. They also spread great distances through air and water, accumulate in human and animal tissues, increase in concentration up food chains, and may have carcinogenic and neurodevelopmental effects. POPs include banned substances such as DDT and toxaphenes, once used as pesticides; polychlorinated biphenyls (PCBs), once used as insulating fluids; and polybrominated diphenyl ethers (PDBEs), still used as flame retardants. Two previous studies attempting to link POPs and FP were unable to rule out the impact of the pollutants on the disease.

"We wanted to do a thorough study looking at a large, statistically valid population of turtles and using methods that could detect even tiny levels of POPs in their tissues," says National Institute of Standards and Technology (NIST) research biologist Jennifer Keller, lead author on the paper appearing in the journal Environmental Science and Technology.

Keller and her colleagues collected turtle blood samples at four locations across Hawaii, each one having a different prevalence of FP—none, low, moderate and high—in the marine turtle population residing there. "We analyzed the plasma for 164 different organic compounds to see if POP concentrations increased with increasing prevalence of FP," Keller says. "We also looked at the levels of halogenated phenols, chemicals which can come from either man-made [POP] sources or naturally from the 's main food source, marine algae."

The researchers discovered that increasing POP concentrations did not correspond with a like rise in the numbers of FP tumors observed. "Our findings show that POPs are not the trigger for FP, so we can eliminate these pollutants from future studies trying to explain why the disease is more common in certain areas or why its prevalence is changing with time," Keller says.

As for halogenated phenols, the team found that the sampled turtles did have detectable concentrations of the compounds. "While it's a novel discovery for sea , we believe that these phenols are likely from the turtle's diet of algae rather than man-made POPs," Keller explains.

Explore further: Europeans have unknowingly contributed to the spread of invasive plant species in the US

More information: *J.M. Keller, G.H. Balazs, F. Nilsen, M. Rice, T.M. Work and B.A. Jensen. Investigating the potential role of persistent organic pollutants in Hawaiian green sea turtle fibropapillomatosis. Environmental Science and Technology. Accepted for publication June 25, 2014, DOI: 10.1021/es5014054

Related Stories

Two studies map pollutant threats to turtles

Apr 27, 2011

(PhysOrg.com) -- In a pair of studies—one recently published online and the other soon-to-be published— researchers at the Hollings Marine Laboratory (HML), a government-university collaboration ...

NZ toxic contaminant levels halved, study shows

Nov 21, 2013

Blood samples taken by Massey researchers to measure the concentrations of toxic environmental contaminants, called persistent organic pollutants (or POPs), show their levels halved in the past 15 years among New Zealand's ...

Recommended for you

Restored streams take 25 years or longer to recover

6 hours ago

New research has found that the number of plant species growing just next to restored streams can take up to 25 years to increase above those channelized during the timber floating era. This is according ...

Why haven't Madagascar's famed lemurs been saved yet?

9 hours ago

Lemurs are cute – there is no denying it. Their big eyes and fluffy faces mean they really are the poster animals of Madagascar, an island known internationally for its unique flora and fauna. But the plight ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.