Screening approaches for the evaluation of endocrine disruption in invertebrates

Chemical toxicity to endocrine processes is recognized as a means by which exposure to low, environmentally-relevant levels of chemicals may result in profound effects at both the organism and population level. Accordingly, toxicologists are faced with the daunting task of developing effective screening tools for the detection of endocrine related toxicity. Invertebrates utilize endocrine processes not found in the vertebrates and thus must be included in such screening processes. Standard toxicity test methods such as the 21-day daphnid and the 28-day mysid reproductive assays can be utilized to evaluate endocrine-related toxicity with the inclusion of appropriate endpoints. Endpoints would encompass neonatal development, growth, maturation, and reproduction (both sexual and asexual). Various anatomical/physiological endpoints are described for daphnids that can be incorporated into standard test protocols for other invertebrates as well. In addition, molecular/biochemical endpoints are described that would provide insight into the mechanisms responsible for the observed toxicity. Such mechanistic information could then be used to identify potentially susceptible groups of invertebrates that should be included in subsequent definitive toxicity characterizations.