ENVIRONMENTAL PERSISTENCE
Agrochemical companies are now obliged to allocate substantial resources to assess the environmental fate of compounds (and their metabolites). The environmental impact of a given pesticide treatment is a function of its properties and the way that contamination takes place. Screening of new compounds includes risk assessment of both ground and surface water contamination, involving computer modelling. A number of standard tests take place on non-target organisms including birds (such as mallard ducks), fish (including rainbow trout), algae, water fleas (Daphnia spp.), bees and other beneficial species. Inappropriate application can lead to off-target contamination due to spray drift, and "run-off" from plants causing contamination of the soil. Several studies have concluded that point source contamination (entry of pesticides to water courses/groundwater following spillage of concentrate or after washing equipment) often causes the greatest harm especially to waterways. During training sessions, time should be allocated to considering crop protection activities relative to the positions of water courses and wells. For example, in order to protect water sources, it is especially important that farmers consider waste flows when washing out sprayers in order to avoid point source contamination.