Environmental and human risks of pesticide use in Thailand and Sri Lanka; results of a preliminary risk assessment

Currently, a major difficulty facing the establishment of sustainable management plans in complex agricultural systems in the tropics is the lack of sufficient relevant information on important ecological, hydrological and land use processes that underpin the various values generated by natural resources. By applying baseline information from two study sites in Thailand and Sri Lanka, the MAMAS project aims at developing cost-effective tests and other environmental diagnostic tools that can ultimately be used in an integrated risk assessment model, leading to the development of policy guidelines for the management of agrochemical use in aquatic systems in Asian countries. The initial stage of the project involved a situation analysis which was followed by a preliminary risk assessment as described in this report. The preliminary risk assessment was aimed at gathering further information on the environmental characteristics of the study sites, in order to estimate potential risks (to both human health and the environment) through pesticide exposures. The information gathered within the MAMAS project was used to model the exposure concentration of the pesticides towards aquatic communities and residues present in food items. This exposure assessmentwas compared with estimated safe concentrations for the environment and human health. Both the environmental and the human health assessment indicated large potential risks. These risks were not only present for the farm channels located next to the cropbut also for larger aquatic systems such as cascade tanks present in Sri Lanka. The next phase of the project will consist of performing chemical measurements, bioassays and biomonitoring (the Triad approach). Data obtained will be used to validate the procedures used in the preliminary risk assessment.