By-Products of Pesticide Manufacture

FIGURE 4.12 Dibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), often called simply dioxin. In the structure of dibenzo-p-dioxin, each number refers to a numbered carbon atom to which an H atom is bound, and the names of derivatives are based upon the carbon atoms where another group has been substituted for the H atoms, as is seen by the structural formula and name of 2,3,7,8-tetrachlorodihenzo-p-dioxin. 

TCDD contamination has resulted from improper waste disposal, the most notable case of which resulted from the spraying of waste oil mixed with TCDD on roads and horse arenas in Missouri in the early 1970s. Contamination of the soil in Times Beach, Missouri, resulted in the whole town being bought out and its topsoil dug up and incinerated at a cost exceeding 100 million. 

One of the greater environmental disasters ever to result from pesticide manufacture involved the production of Kepone, with the following structural formula  

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Masten et al. (1996) investigated the oxidation of chlorinated benzenes such as 1,2-dichlorobenzene (1,2-DCB), 1,3,5-trichlorobenzene (1,3,5-TCB), and pentanoic acid (PA). TCB is often generated as a by-product of pesticide manufacturing, while DCB is commonly manufactured as an insecticide or a fumigant for industrial odor control. Due to their resistance to biological treatments, PA is usually nonreactive with ozone but can react with hydroxyl radicals (Masten et al., 1996). 

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