R4 PM Effects and Risk Assessment of Pharmaceutical and Other Emerging Wastewater Contaminants in Aquatic Systems
Thursday, 17 November 2005: 1:50 PM - 5:30 PM in Ballroom 4

(SOL-1117-854036) Risk assessment of veterinary pharmaceuticals in surface waters of a watershed in Southern Ontario, Canada.

Solomon, K¹, Lissemore, L¹, Hao, C², Yang, P², Mabury, S³, ¹ University of Guelph, Guelph, ON, Canada² Ontario Ministry of Environment, Toronto, ON, Canada³ University of Toronto, Toronto, ON, Canada

ABSTRACT- Few data are available that characterize the sources, exposure and effects of pharmaceuticals in the environment and there is clearly a need to define these parameters within a Canadian context. Of the twenty-nine pharmaceuticals surveyed in a model watershed in S. Ontario, 14 were detected in surface waters. Although not used in agricultural situations, carbamazapine was detected in strictly agricultural watersheds without WWTP inputs. The two most frequently detected antibiotics were lincomycin and monensin. Temporal trends in concentration for 5 frequently detected pharmaceuticals showed pulses occurring between May and November of 2003 at similar but varying times over the seasons, depending on the pharmaceuticals, flow rate, and precipitation. Fluctuations in concentration of ions indicative of agricultural run off, such as nitrate and phosphate, were not found to be useful predictors of changes in pharmaceutical concentration (r² < 0.4). When compared to acute toxicity values or QSAR estimates, distributions of estimated total potency of pharmaceuticals detected in the surface waters suggested small risks from acute effects of mixtures to daphnia, green algae, Lemna gibba, and fish. Microtox assays conducted on extracts of surface waters showed greater toxicity than could be explained by the total potency of the pharmaceuticals detected in the samples. This work was supported by the Canadian Network of Toxicology Centers, Agriculture Canada Livestock Environmental Initiative, and The Beef Cattle Research Council.

Key words: risk assessment, pharmaceuticals, antibiotics