Tracking multiple modes of endocrine activity in Australia's largest inland sewage treatment plant and effluent- receiving environment using a panel of in vitro bioassays

Estrogenicity of sewage effluents, and related ecotoxicological effects in effluent-receiving environments, have been widely reported over the last 2 decades. However, relatively little attention has been given to other endocrine pathways that may be similarly disrupted by a growing list of contaminants of concern. Furthermore, the Australian evidence base is limited compared with those of Europe and North America. During a low dilution period in summer, the authors investigated multiple endocrine potencies in Australia's largest inland sewage treatment plant (STP) and the Lower Molonglo/Upper Murrumbidgee effluent-receiving environment. This STP receives 900L/s of mostly domestic wastewater from a population of 350000, and contributes a high proportion of total flow in the lower catchment during dry periods. A panel of in vitro receptor-driven transactivation assays were used to detect (anti)estrogenic, (anti) androgenic, (anti)progestagenic, glucocorticoid, and peroxisome-proliferator activity at various stages of the sewage treatment process. Total estrogenic and (anti)androgenic potency was removed after primary and/or secondary treatment; however, total removal efficiency for glucocorticoid potency was poorer (53-66%), and progestagenic potency was found to increase along the treatment train. Estrogenicity was detected in surface waters and bed sediments upstream and downstream of the effluent outfall, at maximum levels 10 times lower than low-hazard thresholds. Glucocorticoid and progestagenic activity were found to persist to 4km downstream of the effluent outfall, suggesting that future research is needed on these endocrine-disrupting chemical categories in effluent-receiving systems.