Dietary accumulation and depuration of individual C 10-, C 11- and C 14-polychlorinated alkanes by juvenile rainbow trout ( Oncorhynchus mykiss)

Abstract

Dietary exposures using juvenile rainbow trout ( Oncorhynchus mykiss) were conducted with 19 polychlorinated alkanes (PCAs) with varying carbon chain length (C 10, C 11 and C 14) and chlorine content (4–8 Cl atoms) to determine bioaccumulation parameters. Although these PCAs have the same carbon chain lengths and chlorine content as some chlorinated paraffin (CP) products, all are 1,2-Cl substituted and would not likely be prevalent in commercial CP mixtures. All of the PCAs were rapidly accumulated from the food and had high assimilation efficiencies. Half-lives of PCAs ranged from 7 to 53 d, but in general were much lower than expected for compounds of log K ow of 6 or greater. Half-lives were positively correlated with K ow, carbon chain length and chlorine content. All of the C 14-PCAs, and a number of the higher chlorinated C 10- and C 11-PCAs, had biomagnification factors (BMF) >1, implying a potential to biomagnify in aquatic food chains. BMFs increased with increasing K ow and decreasing carbon chain length. Based on these results and previous work, highly chlorinated short-carbon-chain (C 10–13) PCAs and lower and medium chlorinated (40–60% Cl) medium-carbon-chain PCAs (C 14–18) have the greatest potential for biomagnification among PCAs or CPs. Cl position was also found to influence bioaccumulation parameters. Shorter-carbon-chain and lower chlorinated PCAs appear to be more susceptible to biotransformation by rainbow trout, compared with persistent organochlorines, such as PCBs, studied under identical conditions.