Abstract

A level III fugacity model was developed to evaluate the fate of chemicals in the Cameroon environment. The model required as input physical-chemical properties, mode and amount of chemical released and environmental characteristics. These were used to predict the distribution of the chemical in the environment, quantify intermedia transfer processes and the major loss mechanisms from the environmental compartments. Five pesticides (endosulfan, chloropyrifos, cypermethrin, deltamethrin and λ-cyhalothrin) representing volatile, water soluble and persistent compounds were selected for model evaluation. Furthermore, a sensitivity analysis was performed to identify the key input parameters. Model simulations indicated significant differences in the fate of the chemicals that could be explained by the variation in physical-chemical properties. The log KOW, emission rate to water (EW), volume of the water compartment (VW) and the half-life in water and sediment were identified the as the key parameters influencing the predicted water concentrations. The model developed introduces a cost effective and simple method for screening and identifying priority chemicals. It could also be used to perform baseline exposure and risk assessment of chemicals used in Cameroon where very little data is available for exposure to chemicals due to the huge costs associated with setting up a monitoring program.

Key words: Fate model, fugacity, exposure assessment, chemical fate in Cameroon, persistence.