Chlorobornanes in Water, Sediment, and Fish from Toxaphene Treated and Untreated Lakes in Western Canada

Concentrations of toxaphene (CHB) and 2-exo,3-endo,5exo,6-endo,8,9,10-heptachlorobornane (B7-1001; Hp-Sed), a major toxaphene component known to be present in the sediment of toxaphene treated lakes, were determined in water, sediment, and fish from 13 lakes to examine the relationship between chlorobornane levels in fish and environmental variables. The lakes were situated in either the boreal plain, montane, or subalpine ecozones in western Canada. Five of the lakes had been treated with toxaphene between 1958 and 1962. Mean concentration of CHB (all chlorobornane congeners) in fish from the lakes ranged from 1.9 to 303 μg/kg with the maximum concentration occurring in lake trout from Bow Lake, an oligotrophic glacial fed lake with no record of toxaphene usage. CHB and in particular B7-1001 levels, were higher in water, sediment, and fish from treated relative to matched untreated lakes selected as “control” sites. CHB concentrations in sediment were not related to the levels measured in fish; however, levels of atmospheric CHBAtm (CHBAtm ) CHB [B7-1001]) in fish, from both treated and untreated lakes combined, were inversely related to indicators of lake productivity (p < 0.05, dissolved phosphorus r ) -0.64, percent organic content of lake sediment r ) -0.84, and midsummer water temperature r ) -0.68). These relationships suggest that the process and pathway of CHBAtm accumulation in fish is mediated by limnological and perhaps physiological factors in addition to exposure levels. B71001 concentrations in fish were not related to indicators of lake productivity or the characteristics of fish from the lakes (weight, age, lipid content), but were related to B71001 concentration in sediments (r ) 0.74, p < 0.05).