Investigation of spatial distributions and temporal trends of triclosan in Canadian surface waters

Abstract

Triclosan is widely used in personal care products (skin creams, toothpastes, soaps, deodorants, body spray) and cleaning products (dishwashing detergent and all purpose cleaners) (Halden 2014). In 2001 it was selected for screening level risk assessment under the Canadian Environmental Protection Act (HC and EC 2012), and its physico-chemical and toxicological characteristics indicate that there may be a risk to aquatic environments due to releases of the chemical in Canada. A surveillance initiative across Canada has included sampling at 44 sites from July 2012 to March 2018. Triclosan was detected in 226 out of 918 samples, with concentrations ranging from less than 6 ng L-1 to 874 ng L-1, and the detections averaging 54.23 ng L-1 (standard deviation; 97.6 ng L-1). However, using the entire dataset (including censored data estimated with the Kaplan Meier model) the mean triclosan concentration was 17.95 ng L-1 and the standard deviation was 52.84 ng L-1. Three samples at Wascana Creek (downstream), Saskatchewan, had concentrations above the Federal Environmental Quality Guidelines (FEQGs) of 470 ng L-1, indicating a potential risk to the aquatic ecosystem. In this study, triclosan in samples collected downstream from municipal wastewater treatment plant discharges usually demonstrated higher concentrations than upstream samples. Based on the results of this study, it is hypothesized that triclosan concentration have fluctuated between years of this study but not in an overall or significant increase or decreasing trend. Triclosan concentrations and detections are also more prevalent in urban than in rural or mixed development rivers. Performance evaluation of triclosan concentrations in the Canadian environment is scheduled to be re-assessed by 2024. Therefore a three year sampling program should be in place across Canada by 2021.