Many man made chemicals can be found as environmental contaminants but few generate as much controversy and public fear as pesticides. They are considered to be a special case because they are deliberately introduced into the environment and they are, by their very nature, intended to kill or injure some form of life. In fact much of the public fear of pesticides and their environmental residues derives from the discovery in the 1940s that persistent organochlorine insecticides such as DDT, BHC and more particularly the organochlorine cyclodiene insecticides, viz aldrin, dieldrin, endrin etc. were causing damage to non-target species such as birds of prey (Sen Gupta 1996). These compounds are highly bioaccumulated in the fatty tissues with consequent magnification of (Henry et al. 1998) environmental concentrations through the food chain. In addition, they were found in significant quantities in humans and particularly, in breast milk (Petreas et al. 1996).
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