The chronic physiological effects of the compounds Atrazine, Tributyltin and 17 α-ethinylestradiol were tested on the freshwater aquatic organisms; Hyalella azteca and Daphnia magna. Daphnia magna were exposed to a series of conditions designed to minimize the parthenogenetic cycle of and maximize the sexual cycle resulting in the formation of males and ephippia to be used as a screening assay for potentially endocrine disrupting chemicals. Hyalella azteca were exposed to the three contaminants during a 42-day chronic toxicity assay and analyzed for morphological changes to male secondary gnathopods, female brood pouches and gender ratios. It was found that atrazine, tributyltin and 17 α-ethinylestradiol had no significant effects on the gender ratios or secondary sexual physiology of Hylalla azteca.
The utilization of the freshwater invertebrates hyalella azteca and daphnia magna for use in assessing potential endocrine distruption in aquatic systems
