Relationship of DDE/ΣDDT in Marine Mammals to the Chronology of DDT Input into the Ecosystem

The DDE/ΣDDT (ΣDDT = DDT + DDE + DDD) ratios in the blubber of North Atlantic pinnipeds and odontocete cetaceans, as determined by several scientists and surveys, are compiled to obtain a biannual mean series. Conversion of DDT to DDE is interpreted as being due not only to the marine mammals but also to the overall detoxifying activity of the North Atlantic marine biota. The change of these ratios during the period 1964–81 is examined and a strong correlation between these ratios and time is found in both groups, which demonstrates that such an index can be tentatively used when one assesses the chronology of pollutant input into the ecosystem. An equilibrium value may be reached at the beginning of the next century when the ratio reaches a value of approximately 0.60, provided that no new inputs of contaminant into North Atlantic waters exist.