PARENT SESSION
5C Ecological relevance of endocrine disruption
9:00 AM to 7:00 PM, Tuesday, 08 May 2001
Session Chair:

(T/FF216) Partial life cycle test with Zebrafish: results obtained with various EDCs.

Brandhof, Evert-Jan¹, Bulder, Astrid¹, Folkerts, ArieJan¹, Drüke, Jeanette¹, Beekhof, Piet¹, Ven, Leo¹, Wester, Piet¹, ¹

ABSTRACT- To determine the physiological impact of endocrine disrupting chemicals, we have developed a partial life cycle test with zebrafish as test organism. With this test the effects of a 3-weeks exposure to estrogenic chemicals on the reproduction of adult zebrafish, and on the development of their offspring until 6 weeks of age (after sexual differentiation) were measured. Studied endpoints were: sublethal effects, weight, length, egg production, fertilization rate, hatching rate, plasma vitellogenin (VTG) levels and histological determinants (sexual differentiation, gonadogenesis). The value of this bioassay has been tested with field samples (effluent of a sewage treatment plant), with 17--estradiol (E2) as a reference compound. With these field samples, a significant reduction on the number of broods (i.e. number of eggs) has been observed. The juveniles showed a drastic change in sex ratio (higher prevalence of females). Histological effects were not detected in adults. The effects in the juveniles were similar to those found in the 17--estradiol exposed juveniles. To further develop and validate this bioassay, the zebrafish partial life cycle test is being extended with a set of complementing hormone-active reference compounds, including anti-estrogen, androgen, anti-androgen and anti-thyroid agents. The poster presents preliminary results of the zebrafish partial life cycle test with the androgen 17--dimethyldihydrotestosteron and the anti-estrogen ZM 189,544.

Key words: endocrine disruptors