Intake and excretion of 2,4,6-trichlorophenyl-4′-nitrophenyl ether by topmouth gudgeon,Pseudorasbora parva

Abstract

When the freshwater fish, topmouth gudgeon, was exposed to continuous flow water containing 20 ppb of CNP (2,4,6-trichlorophenyl-4′-nitrophenyl ether), CNP concentration in the fish body gradually increased and reached equilibrium after seven days. CNP concentration and bioconcentration ratio (partition coefficient between fish body and water) after 15 days were 25.3 ppm and 1109, respectively. When the fish was transferred into clean water, the CNP taken into the fish body was slowly excreted and decreased to 0.115 ppm after 30 days. In order to examine distribution and metabolism of CNP in the fish body, an exposure test to static water containing 20 and 100 ppb of¹⁴C-labeled CNP was conducted. The concentration of¹⁴C-CNP equivalent after seven days was decreased in the following order: kidney, viscera except kidney and liver, liver, head, muscle. More than 90% of the toluene-soluble fraction of the¹⁴C in each organ was the parent compound (CNP), and no significant decrease in the concentration of¹⁴C-CNP equivalent in each organ of the fish was found seven days after transfer into clean water. Consequently it appears that CNP is fairly persistent in the fish body.

Several metabolites in the toluene-soluble fraction of fish and water were detected by TLC. Among these metabolites, only amino-CNP andp-nitrophenol were indentified by GLC.