A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest. Pesticides can be classified by their chemical structure (organochlorines, organophosphates and car-bamates) or by their target (herbicides, insecticides, fungicides, rodenticides, pediculocides and bio-cides).The adverse health effects depend on the type of pesticide. Organophosphates and carbamates for example affect the nervous system. Others may irritate the skin or eyes. Some pesticides may be carcinogens.