Contamination by persistent organochlorines in small cetaceans from Hong Kong coastal waters

Blubber samples of 2 cetacean species, the Indo-Pacific hump-backed dolphin (Sousa chinensis) (n = 11) and finless porpoise (Neophocaena phocaenoides) (n = 9), collected from Hong Kong coastal waters were analysed for persist ent organochlorines. Mean concentration in the blubber of DDTs was ranked f irst (46 mu g/g wet wt.), followed by PCBs (24 mu g/g wet wt.), HCHs (0.76 mu g/g wet wt.), chlordane compounds (0.38 mu g/g wet wt.) and HCB (0.07 mu g/g wet wt.). The present cetacean species may potentially be faced with h igh risk due to the elevated level of DDTs and PCBs, Relatively high concen trations of PCBs and DDTs can be attributed to the continuous environmental input of these compounds in the Far East region including Hong Kong, Highl y chlorinated PCBs such as IUPAC Nos. 138, 153, 180 were the prominent cong eners, accounting for 39% of the total PCBs, Mean concentrations of 6 non- and mono-ol tho coplanar congeners were 2.1 and 2.8 mu g/g wet wt. in the h ump-backed dolphin and finless porpoise, respectively. Among highly toxic c oplanar PCBs, mono-ortho congener IUPAC No. 118 and non-ortho congener IUPA C No. 126 were estimated to have the greatest toxicity contribution. Tris(4 -chlorophenyl) methane (TCPMe) and tr is(4-chlorophenyl) methanol (TCPMeOH) , which have been the most recently identified microcontaminants, were also detected with the highest concentration of 290 and 300 ng/g (wet wt, basis ), respectively, The concentrations of TCPMe relative to TCPMeOH in cetacea ns from Hong Kong coastal waters were significantly higher than those found in various seals collected from other parts of the world, suggesting the d ifferent metabolic system of these two compounds between seals and cetacean s, Correlations between the concentrations of tr is-chlorophenyl compounds with other persistent organochlorines such as HCHs, CHLs, DDTs and PCBs wer e significant, suggesting their accumulation nature similar to these organo chlorines. (C) 1999 Elsevier Science Ltd. All rights reserved.