Sharks, dolphins store pollutants

From Montreal, at a meeting of the Society of Environmental Toxicology and Chemistry

Flame-retardant chemicals have become ubiquitous in the environment. A new study finds that in Florida’s top saltwater predators, such as sharks, concentrations of these contaminants and other persistent industrial chemicals are high and increasing rapidly.

Researchers at the State University of New York at Albany and the Florida Fish and Wildlife Conservation Commission in Melbourne teamed up to measure flame retardants called polybrominated diphenyl ethers (PBDEs) and the electric-insulation compounds known as polychlorinated biphenyls (PCBs). The scientists tested coastal-Florida fish and marine mammals.

Fat from prey fish such as perch contained on average about 43 parts per billion (ppb) of PBDEs. Shark species, however, averaged 750 ppb in their fat, and dolphins had 1,190 ppb. A few bull sharks and dolphins were contaminated with PBDE concentrations as high as 4,200 ppb. In various lab animals, these chemicals have impaired hormonal and reproductive function and disrupted fetal development.

PCB concentrations in the top predators were even more dramatic. Sharks had an average concentration of 25,800 ppb in their fat, and researchers found 162,000 ppb in the blubber of bottlenose dolphins. These values are “especially concerning,” says Douglas H. Adams of the Florida wildlife agency.

Most troubling, the researchers say, is that their calculations suggest that PBDE and PCB concentrations are doubling every 2 to 4 years in bull sharks and bottlenose dolphins.

Janet Raloff

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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