Development of an in-stream environmental exposure model for assessing down-the-drain chemicals in Southern Ontario

Abstract

AbstractIn order to address increased interest from scientists and regulators in quantifying environmental risks associated with release of common down-the-drain consumer products, a single-medium contaminant fate model for the lower St. Lawrence drainage basin in Southern Ontario was developed. The model was built within the pre-existing framework of the iSTREEM® in-stream environmental exposure model, which previously only contained US geographies. Data for the model were obtained from Canadian Government sources. In order to assess the model's strengths and limitations, concentrations of the chemicals triclosan and carbamazepine in surface water were compared to the predicted environmental concentrations (PECs) generated by the model for both mean and low flow scenarios. Results of the PECs and the measured surface water concentrations were comparable, with the surface water concentrations generally falling in between the mean and low flow PECs on a cumulative distribution curve.