Are pollutants shrinking polar bear gonads?

The more polluted a polar bear’s fat, the more likely its reproductive organs will be undersize, scientists find.

They collected gonads from 55 male and 44 female bears killed legally by subsistence hunters in east Greenland. The scientists then tested the bears’ fat for pollutants that might affect sex hormones.

Especially in immature males, testis length diminished with increasing concentrations of many of these compounds, including DDT, polybrominated diphenyl ether (PBDE) flame retardants, and banned termiticides called chlordanes. The weight and length of the baculum, a bone that supports a bear’s penis, also decreased significantly with increasing concentrations of some of the compounds.

Ovary length diminished with increasing PCB and chlordane concentrations, and ovary weight decreased with increasing PBDEs, the team reports an upcoming issue of Environmental Science & Technology.

Although studies had suggested that some of these agents might affect animals’ reproduction, “this is the first time it has ever been shown outside the laboratory,” says Christian Sonne of Denmark’s National Environmental Research Institute in Roskilde, who led the new study.

“There’s no doubt” that some of the sex-organ changes observed would impair reproduction, he says. The same pollutants might be related to the falling fertility of men in many countries (SN: 1/22/94, p. 56: http://www.sciencenews.org/pages/sn_edpik/ls_8.htm), he adds.

Janet Raloff

Janet Raloff is the editor of Science News for Students, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer.

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