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Diseases found in dolphins are similar to human diseases and can provide clues to how human health might be affected by exposure to contaminated coastal water or seafood, said a panel of government, academic and nonprofit scientists speaking today at the annual meeting of the American Association for the Advancement of Science, AAAS.

"Dolphins and humans are both mammals, and their diet includes much of the same seafood that we consume. Unlike us, however, they are exposed to potential ocean health threats such as toxic algae or poor water quality 24 hours a day," said Carolyn Sotka of the NOAA Oceans and Human Health Initiative and lead organizer of the session.

"Our ecological and physiological similarities make dolphins an important sentinel species to not only warn us of health risks, but also provide insight into how our health can benefit from new medical discoveries," Sotka said.

Researchers from NOAA and its partner institutions have discovered that bottlenose dolphins inhabiting estuaries along the Georgia coast have the highest levels of polychlorinated biphenyls, PCBs, ever reported in marine wildlife.

PCBs are a group of persistent contaminants that have been banned in the United States since the late 1970s due to documented adverse health effects. The high levels of PCBs measured in the Georgia dolphins, a maximum concentration of 2,900 parts per million, may be suppressing their immune function.

The unique signature of the PCB compounds found in these dolphins is consistent with contaminants of concern at a Superfund site near Brunswick, Georgia.

Scientists are equally concerned about the high PCB levels in dolphins sampled near a marine protected area 30 miles from Brunswick. This suggests that the contaminants are moving along the coast through the marine food web.

"When we received the lab results for the Georgia dolphins, we were alarmed by the contaminant levels and set out to investigate how these heavy chemical burdens were affecting their health," said Dr. Lori Schwacke with NOAA's Center for Oceans and Human Health at the Hollings Marine Lab and co-lead investigator on the team.

Last August, the researcher team conducted a dolphin "capture-release medical physical" on this population and found decreased levels of thyroid hormones, elevated liver enzymes and indications of suppressed immune function.

A pilot study is being undertaken by the National Center for Environmental Health, Centers for Disease Control and Prevention, to examine potential environmental contaminants in residents of nearby coastal communities.

The researchers are investigating whether coastal dolphin populations and human communities sharing the same seafood resources experience similar exposures.