Bioconcentration and distribution of 4-tert-octylphenol residues in tissues of the rainbow trout (Oncorhynchus mykiss)

Branched chain alkylphenols are weak oestrogen mimics which are present in the aquatic environment and have been implicated in the feminisation of fis h. This study reports the biotransformation, bioconcentration and tissue di stribution of the xenoestrogen 4-tert-octylphenol (t-OP) in juvenile rainbo w trout. Fish were exposed for 10 days to a concentration of 4 mug/l of [C- 14] t-OP in a flow-through system and were sampled after 1, 4, 7 and 10 day s of exposure. t-OP residues were extracted from all tissues and analysed b y radio-high-performance liquid chromatography. After 1 day of exposure rad ioactive residues were detected in all tissues and reached steady state con ditions in the whole fish after 4 days of exposure. The concentration of t- OP residues were highest in bile, followed by faeces, pyloric caeca, liver and intestine. In these tissues the majority of alkylphenol was in the form of two metabolites which were identified by gas chromatography-mass spectr oscopy as the glucuronide conjugates of t-OP and t-octylcatechol. t-OP accu mulated as the parent compound in fat with a bioconcentration factor (BCF) of 1190, and in brain, muscle, skin, I,one, gills, and eye with BCFs of bet ween 100 and 260. This study suggests that exposure to water-borne alkylphe nols results in rapid conjugation and elimination of the chemical via the l iver/bile route, but that high amounts of the parent xenoestrogen can accum ulate in a variety of other fish tissues. (C) 2000 Elsevier Science Ltd. Al l rights reserved.