Use of lethal body burdens to indicate species differences in susceptibility to narcotic toxicants

Lethal body burdens (LBB) for 1,2- and 1,4-dihalogenated benzenes (F, Cl or Br) are determined in rainbow trout of two age-classes. LBBs range from 0.3 to 2.4 mmol/kg. There are no significant differences between the two tested age-classes of rainbow trout. The rainbow trout data are compared to LBBs for 1,2- and 1,4-difluorobenzene in fathead minnow which range from 2.7 to 3.0 mmol/kg, and to LBBs of dichloro- and dibromobenzenes in guppy and fathead minnow [Sijm et al. 1993] which range from 2.7 to 8.0 mmol/kg. Rainbow trout are more susceptible to dihalogenated benzenes than fathead minnow. The LBB can be used as an instrument to examine the intrinsic toxicity of a chemical to a species, and to indicate the susceptibility of a species. Possible reasons for differences in susceptibility among species are discussed.