Chlorinated pesticides and polychlorinated biphenyls in marine tucuxi dolphins ( Sotalia fluviatilis) from the Cananéia estuary, southeastern Brazil

Abstract

The Cananéia estuary is an important biological area on the southeast coast of Brazil. In the past, it was impacted by both chlorinated pesticides and polychlorinated biphenyls (PCBs) due to its natural location. The marine tucuxi dolphin ( Sotalia fluviatilis) is a top predator in this ecosystem and can be found year round in Cananéia estuarine waters that represent an important nursing area for the species. This work investigated chlorinated compounds in the blubber of nine individuals from the Cananéia estuary. Residue levels of DDTs (0.541–125 μg g −1 lipid wt.) were the highest, followed by PCBs (0.2–9.22 μg g −1 lipid wt.), mirex (0.014–0.312 μg g −1 lipid wt.), chlordanes (0.001–0.047 μg g −1 lipid wt.), HCHs (<0.003–0.044 μg g −1 lipid wt.), and HCB (n.d.−0.024 μg g −1 lipid wt.). The mean p, p′-DDE/Σ DDT ratio was approximately 0.8 and is indicative of the former DDT application in the study area. PCB contamination is suggested to be associated with atmospheric transport and relative proximity to the Cubatão industrial complex—the most important along the Brazilian coast. Low levels of HCHs and HCB can be attributed to their high volatility in tropical environments. Concentrations of organochlorines in the blubber of marine tucuxis from the Cananéia estuary were lower than levels found in small cetacean species from developed countries, where the input of these compounds was considerably greater than in Brazil. At extremes, male dolphins can present DDT burden several orders of magnitude higher than females. Despite the high levels of total DDT found in males, the major detected compound was p, p′-DDE which is considered to be of low toxicity.