http://hdl.handle.net/10388/11823

Bagatim, Tabata (2019) Characterization of endocrine disrupting potentials of municipal effluents from six wastewater treatment plants across Canada, USASK Harvest - Theses and Dissertations, http://hdl.handle.net/10388/11823

Over the past three decades, concerns have been raised regarding the potential adverse effects of certain natural and synthetic chemicals that can disrupt the endocrine systems of humans and wildlife. These endocrine disrupting chemicals (EDCs) have been reported to cause developmental and reproductive effects at low concentrations (ng/L) in many vertebrate species, particularly in aquatic organisms such as fish. One of the most prevalent sources of EDCs in aquatic environments is municipal wastewater effluents (MWWEs). This is because conventional wastewater treatment systems are inefficient at removing many of the diverse contaminants present in raw sewage, including EDCs. Although multiple initiatives have been initiated to establish standardized testing and monitoring criteria for EDCs in the environment worldwide, our understanding of the contribution of MWWEs to endocrine disruption in Canadian surface waters is incomplete. Therefore, the main aims of this project were to 1) further our understanding of the contribution of MWWEs to the contamination of freshwater bodies in Canada with EDCs, and to 2) characterize the removal efficiency of EDCs by six wastewater treatment plants (WWTPs) across Canada. Specifically, this study explored the presence of EDCs and their potencies in influents and effluents as a function of wastewater treatment level/system, climate/seasonality and population size served by the WWTP using a combination of three in vitro bioassays and targeted chemical analysis. The MVLN, MDAkb2, and H295R Steroidogenesis assays were applied to assess (anti-)estrogenic, (anti-)androgenic and steroidogenesis disrupting potentials, respectively, of extracts of influents and effluents collected throughout the year from the WWTPs of the cities of Saskatoon (SK), Regina (SK), Guelph (ON), Kitchener (ON), Quebec City (QB) and Montreal (QB). In parallel, targeted chemical analysis was performed to determine the presence of selected chemicals with proven or suspected endocrine activities, and results were correlated with bioactivities determined in vitro. Overall, influents showed great androgenic activities regardless of treatment plant while significant estrogenic potentials were only observed in a few cases such as Regina effluent and Montreal influent. With the exception of Montreal, high to moderate treatment efficiencies of WWTPs occurred for the removal of androgens, while low or no removal of substances with estrogenic properties was observed. Significant anti-estrogenic and anti-androgenic potentials were detected in most of the influent and effluent samples, regardless of the treatment level. In general, WWTPs representing less advanced treatment technologies were less efficient at removing certain endocrine active substances. In particular, effluents from the two lagoon-based facilities, Regina and Montreal, had significant remaining estrogenic and androgenic activities, respectively. Furthermore, population size seemed to play an important role regarding EDC removal, with WWTPs serving greater than 500,000 habitants showing decreased removal of compounds with endocrine activities in general. However, given the limited sample size (only two of the cities investigated had populations greater than 500,000 inhabitants) it cannot be determined with certainty whether this decreased removal efficiency was a result of population size or simply insufficient capacities of the WWTPs. Thus, additional studies including more treatment facilities with different treatment levels and larger population sizes should be conducted to determine whether population does significantly affect the removal of EDCs. Furthermore, our original hypothesis that extremely cold temperatures would result in decreased efficiency of EDC removal due to reduced biological activity and light exposure was not always supported by the results. Samples collected during the spring season had the highest endocrine activities overall, which could potentially be a result of colder months. However, neither early nor late winter samples showed a comparable effect on removal efficiency. The observation that spring samples had the greatest endocrine activities may be of significant ecological concern as this season coincides with the spawning season of many fishes. This concern was further corroborated by two parallel studies that investigated the impacts of MWWEs collected from the Regina and Saskatoon WWTPs on fish. These studies observed general inhibition of reproductive functions such as delayed maturation, degeneration of gonadal tissues, reduction in the expression of secondary sex characteristics, and significant reduction of fecundity in fathead minnows exposed to both diluted effluents or that were collected downstream of the WWTP outflow of Regina. The observation that antagonistic effects at both the ER and AR represented the most prevalent endocrine potentials was also supported by chemical analysis that revealed greater concentrations of compounds with the ability to act as ER and AR antagonists, while there were low concentrations or no presence of chemicals previously shown to agonistically interact with these receptors. The results obtained by the combination of in vitro and the two parallel in vivo and chemical analysis demonstrated that in vitro assays can be used as a cost-effective tool for prioritizing potential endocrine disrupting impacts of MWWEs in aquatic environments. The significant endocrine activity, in particular, antagonism of sex steroid receptors, warrants further investigations to characterize the actual risks they may pose to aquatic wildlife. This is particularly true in cases where WWTPs utilize primary and/or outdated lagoon-based treatment technologies, such as Regina and Montreal. Furthermore, in cases where effluent flow is proportionally higher than that of the receiving water body, which can be encountered in many urban municipalities in semi-arid regions such as Regina in southern Saskatchewan, or in situations where the population is greater than WWTPs’ treatment capacity, bypassing untreated sewage, downstream ecosystems may be of particular risk.

https://harvest.usask.ca/bitstreams/52cf4773-2c0b-4d32-9bee-242d9778dc3a/download