Organochlorine residues in the blubber and liver of bottlenose dolphins (Tursiops truncatus) stranded in the Canary Islands, North Atlantic Ocean.

Polychlorinated biphenyls (PCBs) and chlorinated pesticides: dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordanes (CHLs), dieldrin, and hexaclorobenzene (HCB) were detected in the blubber and liver of 11 bottlenose dolphins (Tursiops truncatus) from the Canary Islands (North Atlantic Ocean). Samples were obtained from stranded dolphins over the period 1997-2005. Among the organochlorines analyzed, PCBs and DDTs were predominant in the two tissues, followed in decreasing order by chlordane, trans-nonachlor > cis-nonachlor > dieldrin and HCB. The sum 11 PCBs in the blubber ranged between 301 and 33,212 ng g(-1) ww (990 and 136,679 ng g(-1) lw). Highly chlorinated PCBs such us CB153, CB180, and CB138 were the prominent congeners, accounting for 51% of the total PCBs. The sum DDT concentration in the blubber ranged between 147 and 21,050 ng g(-1) ww. (490-105,250 ng g(-1) lw) The main DDT metabolite was p,p'-DDE, representing 83% of DDTs in the blubber. In general, the levels of PCBs and DDTs detected were similar to those found in bottlenose dolphins in the North of Europe. The 2,3,7,8-TCDD toxic equivalent (TEQ) in blubber and liver was calculated for the toxicity assessment of mono-ortho substituted PCBs congeners (CB105, CB118, CB156). It is important to mention that TEQ values and p,p'-DDE concentration in adult male specimens are approaching the levels associated with adverse effects found in marine mammals. The information provided represents the first tissue loads of organochlorine compounds in small cetaceans from this area.
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