The effects of suspected
endocrine disrupting chemicals on freshwater and marine prosobranch species were analysed in laboratory experiments. In this last of three publications, the responses of the fresh water snail Marisa cornuarietis and of two marine prosobranchs (Nucella lapillus, Nassarius (Hinia) reticulatus) to the antiandrogenic model compounds
cyproterone acetate (CPA) and
vinclozolin (VZ) are presented. The snails were exposed to nominal CPA concentrations of 1.25 mg/L alone and simultaneously to a potent
synthetic estrogen (ethinylestradiol),
androgen (
methyltestosterone) or an indirectly acting xeno-
androgen (
tributyltin) in experiments with adult specimens and in a life cycle test for 12 months. Marisa and Nucella were furthermore exposed to nominal concentrations of 0.03-1.0 microgram VZ/L for up to 5 months. The
antiandrogens induced a number of
biological responses in all three species. The length of the penis and of accessory male sex organs (e.g., penis sheath, prostate) were significantly reduced. For Marisa, this effect occurred only in sexually immature specimens and was reversible as the males attained puberty. Typical
androgen-mediated responses (imposex development, delayed spermatogenesis, tubulus
necrosis of the testis with
orchitis and Leydig cell
hyperplasia) were partially or totally suppressed by a simultaneous administration of CPA. In the two marine species even adult, sexually mature males responded to
antiandrogens with a reduction of the male sex organs and an advancement of the sexual repose phase. The results for CPA and VZ are compared with the effects of an exposure to xeno-
estrogens (
bisphenol A,
octylphenol) and xeno-
androgens (
triphenyltin,
tributyltin) in the same species. Each group of
endocrine disruptors induces a characteristic set of toxicological effects in prosobranch snails which can be used as endpoints in an organismic invertebrate test for the identification of endocrine mimetic test compounds.
Estrogens cause primarily an induction of superfemales resulting in an increased female mortality by the enhancement of spawning mass and egg production. The main effects of
androgens are a
virilization of females by imposex development and a marked decrease of the fecundity. Compared with
estrogens and
androgens, the
antiandrogen responses seem to be less drastic and might have--in contrast to the two other disruptor classes--no biologically significant effects at the population level.