Critical body residues (CBRS): Applications in the assessment of pentachlorophenol toxicity to Eisenia fetida in artificial soil

Acute lethality tests were conducted using Eisenia fetida exposed to pentachlorophenol (PCP) in artificial soil. Mortalities were monitored intensively over the first 24 h, followed by observations every 48 h for the duration of the 28-day test. Toxicity curves were fitted to data using a one-compartment first-order kinetics model (1CFOK) to determine incipient lethal levels (ILLs). PCP residues were determined by gas chromatography after cryoextraction. The 1CFOK model provided a good fit to the observed data. Critical body residues (CBRs) ranged from 0.33 to 2.65 mmol PCP kg−1 wet wt, even though soil concentrations of PCP ranged over three orders of magnitude. The consistency of CBRs regardless of soil concentrations suggests that they may be a useful tool in assessing the toxicity of soil contaminants to earthworms.