Reproductive and developmental effects of endocrine disrupters in invertebrates: in vitro and in vivo approaches.

In order to gain basic understanding in the ecotoxicity of endocrine disrupting chemicals or EDCs (including natural chemicals and some pharmaceuticals), many international research groups are currently testing these chemicals using aquatic invertebrates. This paper discusses relevant examples to address key questions: which aquatic invertebrates are likely to be vulnerable to mammalian and non-mammalian EDCs; and which types of invertebrate chronic tests might be most sensitive and cost-effective to address potential environmental exposures? For a full review of invertebrate endocrine disrupter research see Endocrine Disruption in Invertebrates: Endocrinology, Testing and Assessment (1999). As an example, crustaceans are a particular focus of EDC research, reflecting their abundance in nature, commercial importance and their inclusion in the regulatory assessment schemes for active pharmaceutical ingredients (APIs). There is a diverse literature on the developmental and reproductive effects of mammalian EDCs in Crustacea, although there is growing evidence that such effects are probably not mediated via arthropod hormone systems. For example, recent studies in Europe using a marine copepod (Tisbe battagliai) life-cycle test have evaluated ecdysteroid agonists (e.g. 20-hydroxyecdysone), oestrogen agonists (e.g. diethylstilbestrol (DES), 17beta-oestradiol, oestrone and 17alpha-ethynylestradiol) and the pharmaceutical anti-oestrogen (ZM189, 154). While 20-hydroxyecdysone and DES were highly toxic, the other compounds tested show no significant toxicity to copepods. Furthermore, in vitro studies indicate that these environmental EDCs and several related APIs are not active against the ecdysteroid receptor. Therefore, other undefined modes of action appear to be responsible for crustacean toxicity in vivo and caution should be exercised before ascribing any apical effects to endogenous endocrine mechanisms, or before crustacean "EDC" data are extrapolated to other invertebrate taxa.