HISTORICAL-PERSPECTIVE ON THE ENVIRONMENTAL BIOAVAILABILITY OF DDT AND ITS DERIVATIVES TO GULF OF MEXICO OYSTERS

DDT and its metabolites, DDD and DDE, were analyzed in 479 oyster samples from the Gulf of Mexico between 1986 and 1988 as part of the National Status and Trends “Mussel Watch” (NS&T) Program. DDT and/or its derivatives were found in every sample analyzed in concentrations ranging over 2 orders of magnitude. DDT accounted for 3–6% of the total DDT burden in oysters. The remaining percentage was approximately equally distributed between DDD and DDE. After the first 3 years of the NS&T program, the geographical distribution of total DDT along the northern coast of the Gulf of Mexico has been well defined. Based on 3 years of data, there were only a few sites that had statistically significant monotonic changes in concentrations with time. However, when the present data set is compared to historical data for the Gulf of Mexico, a general decrease is observed. The rate of DDT disappearance, as monitored by Gulf of Mexico oysters, is comparable with its decline in other marine environments. © 1990, American Chemical Society. All rights reserved.