Analysis of Gulf of Mexico bottlenose dolphins for organochlorine pesticides and PCBs.

Organochlorine concentrations were determined in blubber samples from 33 Tursiops truncatus stranded on the Texas and Florida coastlines. All tissues had measurable concentrations of 4,4'-DDE (0.18-70.7 microg/g lipid weight) and SigmaPCB (4.1-149 microg/g lipid weight). Pesticide and PCB concentrations were similar to those reported in Tursiops truncatus from the Atlantic coast of the United States and the southeast coast of Africa. Organochlorine concentrations were highest in mature males, and differences in the SigmaPCB/SigmaDDT ratios between mature and immature males suggests a recent decrease in DDT uptake, related to the commercial DDT ban in the US in 1971, as well as dietary differences between younger and older animals. Analysis of a female and her calf indicate that females reduce their own organochlorine body burden through transplacental transfer. However, no reduction of some higher molecular weight PCBs was found. Transplacental transfer rates of 5.1% for SigmaDDT and 3.7% for SigmaPCB were determined based on a stranded female and her full term, unborn calf. Predictions of uptake and depuration rates of organochlorines based on gender in Tursiops truncatus agree with clearance rates from previous studies.