Sea Turtle Tumor Disease is Surprisingly Not Caused by Organic Pollutants

For years, researchers have thought that organic pollutants could be contributing to green turtles' susceptibility to the virus that causes fibropapilomatosis (FP), a disease that creates tumors that can inhibit the animal's sight, mobility and feeding ability. Now, though, scientists have found that organic pollutants don't factor into this tumor turtle disease, which could mean further research may be needed to find out exactly what is causing this sickness.

Persistent organic pollutants, or POPs, are a large group of manmade chemicals that persist in the environment. They spread great distances through both air and water and can accumulate in biological tissues, such as fat. In fact, these chemicals can be found in higher concentrations the further up the food chain you go, and may have carcinogenic and neurodevelopmental effects. POPs include substances such as DDT and toxaphenes along with PCBs, PDBEs and others.

In order to see whether POPs were causing the tumor seen in green sea turtles, the scientists collected turtle blood samples at four locations across Hawaii. Each turtle had a different prevalence of FP-none, low, moderate, and high.

"We analyzed the plasma for 164 different organic compounds to see if POP concentrations increased with increasing prevalence of FP," said Jennifer Keller, lead author of the new paper, in a news release. "We also looked at the levels of halogenated phenols, chemicals which can come from either manmade sources or naturally from the green turtle's main food source, marine algae."

In the end, the researchers found that increasing POP concentrations didn't correspond to the number of FP tumors. This seemed to indicate that POPs were not a trigger for FP.

The findings have implications for the disease that causes tumors in sea turtles. More specifically, it shows that the disease may just work on its own or that other factors might be influencing its progress.

The findings are published in the journal Environmental Science and Technology.