Occurrence of pesticides in Swedish water resources against a background of national risk-reduction programmes - results from 20 years of monitoring

One important aim of the new EU thematic strategy on the sustainable use of pesticides is the protection of the aquatic environment. The intention is to reduce levels of harmful substances and the need for monitoring programmes is stressed, including the determination of concentrations of pesticide residues in water. Sweden has long-term experiences in pesticide monitoring programmes and also in the implementation of risk-reduction programmes for the use of pesticides. To assess the effects of political decisions, information on occurrence of pesticide residues in Swedish waters is collected and stored in a national database. Results from analyses of surface water and groundwater throughout Sweden now cover a 20-year period (1985-2005). The data show that the incidence of samples with a total pesticide concentration above 0.5 μg/L has decreased over the years, both from surface and ground waters. Especially in surface waters, having shorter pathways between the site of application and the receiving water body there has been a notable decrease in pesticide concentrations. This positive development is likely the result of some of the national risk-reduction measures introduced