Brendan Smith

Brendan completed his MSc in the Servos Lab, where he evaluated the estrogenic activity of municipal wastewater effluents in the Grand River watershed of southern Ontario. His research focused on three municipal wastewater treatment plants (Guelph, Waterloo, and Kitchener) that have been identified as contributing to endocrine-disrupting effects in fish, particularly those associated with estrogenic compounds, while also undergoing infrastructure upgrades to accommodate increasing urban demand.

Using a combination of in vivo and in vitro approaches, his work assessed whether wastewater effluents induced estrogenic responses in fish. Rainbow trout (Oncorhynchus mykiss) were exposed to varying concentrations of effluent, and plasma vitellogenin (VTG) was measured as a biomarker of estrogen exposure. In these controlled exposures, neither Guelph nor Waterloo effluents induced significant VTG responses under the tested conditions, although in vitro yeast estrogen screen (YES) assays indicated measurable estrogenic activity across all effluents, with levels varying by degree of treatment.

His research also included pilot-scale wastewater treatment comparisons, where only one treatment configuration produced a weak VTG response, aligning with slightly elevated estrogenic equivalents measured in vitro. To further identify causative compounds, an effect-directed analysis (EDA) was applied to Waterloo and Kitchener effluents. This approach identified estrone as the primary contributor to estrogenicity in Waterloo effluent, while Kitchener effluent estrogenicity was associated with a mixture of compounds including estrone, 17β-estradiol, bisphenol A, and testosterone.

Overall, his work demonstrated the value of integrating biological assays with chemical fractionation approaches to better resolve the drivers of estrogenic activity in complex wastewater mixtures, and to improve understanding of how municipal effluents influence aquatic endocrine disruption.