Persistent organochlorine residues in small cetaceans from the east and west coasts of southern Africa.

Organochlorine pollutant levels in the blubber of small cetaceans and ratios between concentrations of compounds, such as DDE/tDDT and tDDT/PCB, were used to identify the chronology of input of DDT and PCB into the coastal waters along the west and east coasts of southern Africa. Although regression analyses, with time as the only independent variable, do not show a statistically significant decline in tDDT from 1980 to 1987 in the common dolphin from the east coast of South Africa, there is a fairly strong indication that tDDT concentrations did not increase or even stay constant with time. tDDT concentrations in the bottlenose dolphin declined significantly from 1980 to 1987 (P < 0.05). The regression analyses for PCB in the bottlenose dolphin from the east coast show no decline (P > 0.05). The data from this study illustrate that it would take a long time in the coastal waters and open ocean before the restriction and prohibition on the production and use of organochlorines will take effect.