Bioaccumulation profiles of polychlorinated biphenyl congeners and organochlorine pesticides in Ganges river dolphins

Abstract

Isomer‐specific concentrations of polychlorinated biphenyls (PCBs) including non‐, mono‐, and di‐ortho‐substituted congeners, DDT and its metabolites, hexachlorocyclohexane (HCH) isomers, chlordane compounds, and hexachlorobenzene (HCB) were determined in river dolphin blubber and prey fishes collected during 1993 through 1996 from the River Ganges in India. Concentrations of organochlorines were also measured in the milk and liver of dolphins, benthic invertebrates, and sediments. The DDTs and PCBs were the predominant compounds found in dolphin tissues and fish that comprise the diet of dolphins. Concentrations of DDTs and PCBs in the blubber of dolphins were in the range of 30 to 120 and 1.5 to 25 μg/g, lipid weight, respectively. Pentaand hexachlorobiphenyls collectively accounted for 68 to 80% of the total PCB concentrations in river dolphins. Hexachlorobiphenyl congener 138 (2,2′,3,4,4′,5′‐) was the most abundant in dolphin blubber and prey fishes. The isomer/congener pattern of PCBs and organochlorine pesticides suggested that there is less metabolism due to cytochrome P450 enzymes in Ganges river dolphins than in marine or terrestrial mammals. The mean 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin equivalents (TEQs) estimated in river dolphin blubber was greater than those that can cause adverse effects in mink. Comparison of organochlorine concentrations in river dolphins with those of the values reported for samples analyzed during 1988 through 1992 suggested that the contamination by these compounds has increased in the River Ganges.

Linking pollutant exposure of humpback whales breeding in the Indian Ocean to their feeding habits and feeding areas off Antarctica

“…Due to their chemical properties, HCHs are easily volatilized and transported by air and water currents for long distances (Iwata et al, 1993;Wania and Mackay, 1993). Although Canada, Europe, and the U.S. have banned HCHs since the 1970s, several tropical countries still used lindane (pure g-HCH) until the 1990s (Li et al, 2003;Senthilkumar et al, 2001Senthilkumar et al, , 1999, influencing thus the occurrence of g-HCH in Antarctic food webs. Humpback whales feeding in the Antarctic Peninsula region displayed a high percent contribution of lindane (g-HCH) to the SHCH, as a consequence of lindane use in South America close to the Peninsula (Dorneles et al, 2015).…”

Pesticide use and application: An Indian scenario

“…Tanabe et al [68] and Takeoka et al [69] evaluated the transport of HCHs from land to sea in a paddy field and adjoining estuarine systems in southern India and found out that major portion of the HCHs used is removed to the air and contribute both to the regional and global pollution. A series of studies from other workers showed the existence of various pesticides in samples of air [70][71][72][73], water [70,[74][75][76][77][78][79][80][81][82][83][84][85], soil and sediments [69][70][86][87][88][89][90][91][92][93][94][95][96][97][98] wildlife including dolphins, sharks and mussels [99][100][101][102][103][104][105][106][107], fish [106,108,109] birds [88,…”

Dioxins and organohalogen contaminants in the Asia-Pacific region

“…4, most of OCs accumulated in the archived samples of Baikal seals (Phoca sibirica), a representative species living in inland water, were on a declining trend during 1992-2002 Tsydenova et al 2004). This result indicates that the regulation of OC production and usage following the recommendation by World Health Organization (WHO), Food and Agriculture Organization 1988/1992-1994/1996(Senthilkumar et al 1999Tanabe et al 2003). In particular, levels of PCBs, DDTs and HCHs in Ganges River dolphin increased about 2.5 times during the study period.…”