ELIMINATION RATES OF SELECTED DI-ORTHO, MONO-ORTHO, AND NON-ORTHO SUBSTITUTED POLYCHLORINATED-BIPHENYLS IN RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

In older to determine the influence of chlorine substitution pattern o n elimination rate constants for polychlorinated biphenyls (PCBs), 60 rainbow trout (Oncorhynchus mykiss) were intraperitoneally injected wi th corn oil spiked with a mixture of 13 tetra- to hexachlorobiphenyls. The mixture consisted of four di-ortho congeners (International Union of Pure and Applied Chemistry no. 52, 47, 101, and 153), five mono-or tho congeners (66, 105, 118, 119, and 156), and four non-ortho congene rs (81, 77, 126, and 169). The range in growth-corrected elimination r ate constants for the non-ortho-substituted PCBs was 0.003 to 0.015 mu g/kg per d. The range of elimination rate constants for the mono-orth o PCBs was 0.007 to 0.012 mu g/kg per d. and the range for the di-orth o PCBs was 0.004 to 0.011 mu g/kg per d, Multivariate analysis of cova riance revealed a highly significant interaction between chlorine subs titution pattern and time (p < 0.001), suggesting that substitution pa ttern influences elimination kinetics. K-ow and time also revealed a s ignificant interaction (p < 0.001), As structure can influence rates o f chemical elimination, exposure dynamics of PCBs are a function of bo th hydrophobicity and substitution patterns. The study confirms the ob servation that the predicted rate of decline of some of the more toxic non-ortho PCBs might be less than that observed for total PCBs.