Development of a Reproductive Performance Test for Endocrine Disrupting Chemicals Using Pair-Breeding Fathead Minnows (<i>Pimephales promelas</i>)

Abstract

Existing in vivo tests (with the exception of the full life-cycle test) are not adequate for assessing the reproductive effects of endocrine disrupting chemicals (EDCs) on fish, and hence the need for partial life-cycle tests has been recognized internationally. In this paper we describe the development of a short-term (6 week) reproductive performance test for EDCs using pair-breeding fathead minnows (Pimephales promelas). In the test, reproductive performance in paired fish is assessed over two 3 week periods, one with exposure to the test chemical and one without. The test is highly integrative and measures effects of exposure to chemicals on fecundity, gonadosomatic index (GSI), vitellogenin (VTG) induction, and secondary sexual characteristics (fat pad and tubercles in males). In this test, exposure to butyl benzyl phthalate (BBP) at a nominal concentration of 100 μg/L (measured concentration between 69 μg/L and 82 μg/L) had no discernible effects on reproductive performance. In contrast, all reproductive parameters measured were affected by exposure to 4-NP, albeit some (e.g. VTG induction and reduction in the prominence of secondary sexual characteristics − lowest effective dose between 0.65 μg/L and 8.1 ± 1 μg/L [measured]) were more sensitive than others (e.g. number of eggs and spawnings, where the lowest effective dose was between 8.1± 1 μg/L and 57.7 ± 3 μg/L [measured]). Concentrations of 4-NP at or above 48 μg/L [measured] inhibited reproduction completely.