Effect of total body lipid on the toxicity and toxicokinetics of pentachlorophenol in rainbow trout (Oncorhynchus mykiss)

Abstract

Juvenile rainbow trout were fed high fat (21%) or low fat (13%) practical diets for 11 wk in order to establish a significant difference in total body lipid; a difference of 3% was obtained. An acute lethality test (144 h) was performed on the two diet groups using pentachlorophenol (PCP). Elimination rate constants ( k 2) and acute lethality thresholds were estimated by fitting a one-compartment, first-order bioconcentration model to both the LC50/time data, and the time-to-death/water-concentration data. Estimates using these two methods were, respectively, 2.32 and 2.29 d −1 for the high fat treatment, and 2.84 and 2.66 d −1 for the low fat treatment. There was no significant difference in the resistance of fish to PCP due to lipid or weight as determined by a regression of time-to-death on these variables. Whole-body PCP levels, were measured in individual fish that died during the bioassay. Mean lethal body residues were found to range from 0.08 to 0.15 mmol PCP kg −1 and significant differences were found between both diet treatments and exposure concentrations. Analysis of covariance on the lethal residue data showed that lipid levels interacted significantly with exposure concentration, suggesting that the fish do not act as an ideal single compartment. Correction of PCP residues for fish lipid content showed that some of the variation in lethal body burdens could be accounted for by lipid content. In fish which survived the lethality bioassay at 91 μg 1 −1, lipid levels were significantly decreased compared to initial levels. At the 91 1 −1 μg exposure concentration PCP residues were not correlated with the body lipid content.