Risk Assessment for a Chemical Spill into a River

Abstract

A chemical spill into a river presents a significant threat to human health and the aquatic environment. A mathematical model is presented for predicting the chemical concentrations in a river resulting from a chemical spill. A screening risk assessment approach is presented to characterize the risk to humans and aquatic life resulting from a single spill. Human exposure is evaluated using two approaches; exposure from drinking contaminated water and aggregate exposure. The potential for adverse effect to aquatic organisms is evaluated by comparing the predicted environmental concentrations to the lethal effect concentration for the most sensitive species as well as to the no observed effect concentration. The model and the approach are used to evaluate a small hypothetical spill of methanol. The example provides guidance for evaluating other chemical spill scenarios.