Pesticides are substances, mainly used in agriculture, which influence processes in living organisms and are used to control harmful organisms (weeds, insects) in agriculture. These substances can be water toxic, carcinogenic, reproductive toxic or endocrine disruptive. They have a harmful impact on biological diversity, with short-term toxic effects on directly-exposed organisms, and long-term effects resulting in changes to habitats and to the food chain.

Wood preservatives, disinfectants, rodenticides, textile preservatives or household-insecticides are amongst the most used pesticides.