Chlorinated Pesticides: Aldrin, DDT, Endrin, Dieldrin, Mirex

Abstract

This chapter provides an overview of history, chemistry, environmental fate and effects of DDT and of the cyclodiene pesticides aldrin, dieldrin, endrin, and mirex, and their metabolites and degradation products. These pesticides are, for the purpose of this review, summarily called the ‘classic organochlorines’ (COC). All cyclodiene COC have been practically phased out. DDT is still used in several countries, to some extent in agriculture, but primarily, to control malaria. Common structural features of COC are the presence of several chlorine atoms and a rigid shape of the molecule. Common properties include very low solubility in water and high solubility in lipids, low but significant vapor pressure, and a strong resistance to degradation. The consequences of this combination of properties include a wide distribution and persistence in the environment and accumulation in biota. A prolonged presence in biota results in a number of chronic effects, not anticipated from short-term toxicity studies. COC and similar compounds are not likely to be again released intentionally into the environment; thus this chapter documents a history which will not, hopefully, be repeated. The story should serve as example of difficulties in anticipating environmental effects of chemicals, unexpected consequences, and changing attitudes and terms of reference. Studies of COC contributed a great deal to the understanding of the behaviour of chemicals in the environment; however, nothing can be done about the trace concentrations of COC now present there. An important lesson has been learned and it is time to start paying attention to the detection, behaviour, and effects of many other chemicals released into the environment.