Disposition and metabolism of [3H]-4-n-nonylphenol in rainbow trout

In order to better understand the fate of nonylphenols consumed by aquatic vertebrates, the fate of low (6 μg kg−1) and high (25 mg kg−1) doses of [3H]4-n-nonylphenol was followed 48 h after a single oral dose. In the low dose experiments 7.6 and 7.2% of the dose was excreted into urine or bile whereas 46.5% was still present in other tissues of the fish. In the high dose experiment these compartments comprised 3.0, 5.5 and 11.0% of the dose respectively. Radioactivity was widely distributed in trout tissues and organs, the highest concentration being in the digestive tract, liver and kidney. No identification of the nature of residues was performed on these tissues. A radio-HPLC system was developed for the analysis of biliary metabolites. Based on this method, more than 10 metabolites were separated and tentatively identified by mass spectrometry. A major part of metabolites were glucuronic acid conjugates of nonylphenol and related hydroxylated compounds. Hydroxylation and oxidation occur on the alkyl chain whereas indirect evidence exists of an hydroxylation on the phenol ring of the molecule. No trace of unchanged nonylphenol was found in bile and urine