Intraspecies variation in lethal body burdens of narcotic compounds

Groups of fathead minnows were exposed to different concentrations of di- or trichlorobenzenes, tetrachloroethane or PCBs. Lethal body burdens (LBB, mmol compound/kg wet weight) were determined. The purpose of the study was to obtain information on the variability of the LBB within a population, and on the reasons for this variability. The variation in LBB within a population was 4- to 23-fold for the chemicals tested. Approximately 50% of this variation could be attributed to the lipid content of the individuals. The LBB did not depend on the weight of the fish. The exposure time until lethality did not influence the LBB for the di- and trichlorobenzenes and tetrachloroethane. In contrast, the LBB of the PCBs was influenced by this parameter, a shorter exposure time resulting in a lower LBB.