| Abstract
| - Conjugates of estrogenic chemicals, endogenous as wellas xenobiotic, are mainly excreted via bile into the intestine.Therefore, measurement of estrogenic activity in bileyields useful information about an organism's internalexposure to (xeno-)estrogens. Although previous studiesin The Netherlands have reported estrogenic activity in malefish bile, the contribution of natural hormones andxenobiotic substances to this activity is unknown. Toidentify compounds responsible for estrogenic activity infish bile, we developed a bioassay-directed fractionationmethod for estrogenic chemicals. In this approach, the invitro reporter gene assay ER-CALUX (Estrogen ResponsiveChemical Activated Luciferase Gene Expression) wasused to assess estrogenic activity in deconjugated bilesamples and to direct RP-HPLC fractionation and chemicalanalysis (by GC−MS) of estrogenic compounds. Themethod was applied to bile from male breams (Abramisbrama) collected at three locations in The Netherlands. Atone of these locations, the River Dommel, extremelyhigh levels of plasma vitellogenin and a high incidence ofintersex gonads in these male breams have previouslybeen observed, indicating the exposure to estrogens. Inthis study, the natural hormones 17β-estradiol, estrone, andestriol accounted for the majority of estrogenic activityin male bream bile. At the River Dommel, the syntheticcontraceptive pill component ethynylestradiol was found ineffective concentrations as well. The detected naturaland synthetic hormones may be responsible for the estrogeniceffects observed in wild bream from this location.Furthermore, a large number of xenobiotic chemicals wasdetected at relatively high levels in bile, including triclosan,chloroxylenol, and clorophene. Although chloroxylenol wasshown for the first time to be weakly estrogenic, thesecompounds did not contribute significantly to the estrogenicactivity observed.
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