pesticides are various categories of chemical agents used by man to enhance agricultural production and control disease vectors
– often toxic to non-targeted organisms when they get into the  ecological food chain
– many, kill organisms directly or affect their reproductive processes
– many persist in the environment (soil, rivers, lakes, etc)
– variable amount may remain in living organisms and transmitted along the food chain
– may get more concentrated as the food chain ascend
– endangers wild life and man
– examples are DDT, Gamalin, Karate