155 
the main metabolite (Barrett et al. 2000; Simon, 2001; Yiicel et al., 1999; Watson, 
2002). 
Precautions and restrictions are imposed by EPA in order to reduce potential hazards 
(Extoxnet Information about Chlorpyrifos, 1993). 
Chlorpyrifos-methyl has the same skeletal structure as chlorpyrifos-ethyl but the two 
ethyl groups are replaced by two methyl groups ( Figure 24). The compound is used to 
protect stored grain against insect infestation, which includes weevils, beetles, and 
moths. It was registered after 1984 and is manufactured and marketed by Dow under the 
trade name Reldan® (Bangs, 2000). Chlorpyrifos-methyl shows a moderate acute 
toxicity for mammals (LD50-value = 3000 mg/kg bodyweight rat (Rompp, 1995)). 
6.2.2 Dicofol 
Figure 25: Structures of dicofol (A) and its main metabolite 4,4’-dichlorobenzophenone (B) 
Dicofol - marketed under the trade name Kelthane® - is a member of the group of 
organochloride insecticides (Figure 25). There is only a single manufacturer of Dicofol 
in Europe, based in north-east Spain. The annual total production at this plant is 1500 t. 
290 t of this volume is used in Western Europe as an acaricide for the treatment of fruit, 
vegetables, and crops (Background Document on Dicofol, 2002). Important physico 
chemical properties of dicofol are listed in Table 54.