The leaching characteristics of wood preservatives from treated wood exposed to different environmental conditions affect both the long-term efficacy of the treatment against target organisms and the environmental impacts of the treatment. In the risk assessment of new and currently in-use wood preservatives, it is important to have representative estimates of the leaching rates of the preservative components under different exposure scenarios and to understand how these leaching rates change with time and other variables. This information, in combination with data on dilution and fate of substances in the environment, permits the estimation of predicted environmental concentrations (PECs) at any time in service.