Fish Bile Analysis for Monitoring of Low Concentrations of Polar Xenobiotics in Water

Abstract

The chemical analysis of fish bile has the potential to provide good information about the internal dose and to facilitate the monitoring of polar water-borne xenobiotics. Primary attention has been given to establishing the relationship between water concentration and the ratio of concentrations in the bile and the water (bile bioconcentration factor, bBCF) of a model compound, 4,5,6-trichloroguaiacol (4,5,6-TCG), in fourhorn sculpin(Myoxocephalus quadricornis), at water concentrations typical for a recipient of bleached kraft pulp mill effluents. The concentration in bile of 4,5,6-TCG includes also its conjugates. 14C- and 3H-methyl-labeled 4,5,6-TCG was used for short-term and long-term exposure of rainbow trout (Salmo gairdneri) and fourhorn sculpin, respectively, in laboratory experiments. The results of liquid scintillation measurements indicate an efficient metabolism and elimination of 4,5,6-TCG in fish. Chemical analysis (high pressure liquid chromatography, HPLC) of the bile from rainbow trout exposed to radioactive-labeled 4,5,6-TCG showed a predominance of glucuronide conjugates. In fourhorn sculpin a significant fraction of sulfate ester was also identified. The results from the exposure experiments with fourhorn sculpin demonstrate that the concentration in the fish bile of 4,5,6-TCG with conjugates under certain circumstances correlates in a linear manner with the water concentration of free 4,5,6-TCG, allowing an estimate of the bBCF at around 7 xl04.