ABSTRACT
Organochlorines (OCPs) and organophosphates (OPPs) were the rst synthetic pesticides developed and are among the prominent families of these compounds. Figure 19.1 shows the chemical structures and names of several OCPs and OPPs. The rst synthetic OCP, DDT (dichlorodiphenyl-trichloroethane), discovered in Switzerland in 1939, was very effective and used extensively to control head and body lice, human disease vectors and agricultural pests, in the decades leading up to the 1970s (Rosenfeld and Feng 2011). Benzene hexachloride (BHC) and chlordane were discovered during World War II, and toxaphene (and heptachlor) slightly later (Cheremisinoff 2011; Hodgson 2010; Plestina 2003; Plimmer 2001). Shortly thereafter, two cyclodiene organochlorines, aldrin and dieldrin, were introduced, followed by endrin, endosulfan, and isobenzan. They operate by disrupting the sodium/potassium balance of the nerve ber, forcing the nerve to transmit continuously. Many of them are endocrine-disrupting chemicals, meaning that they have subtle toxics effects on the body’s hormonal systems. Their toxicities vary greatly, but they have been phased out because of their persistence and potential to bioaccumulate (Bolognesi and Merlo 2011; Cheremisinoff 2011; Keifer et al. 2005; Nasterlack 2011). These properties of persistence and bioaccumulation eventually led to the withdrawal of registration and use of organochlorine insecticides, from 1973 to the late 1990s, in industrialized nations, although they continued to be used in developing countries. According to the Stockholm Convention on Persistent Organic Pollutants, 9 of the 12 most dangerous and persistent organic chemicals are OCPs (Cheremisinoff 2011).
