A survey comparing the chemical composition of dicofol formulations sold in the UK before and after the introduction of the EC 'Prohibition Directive 79/117/EEC'
1994
Gillespie, M.J. | Lythgo, C.M. | Plumb, A.D. | Wilkins, J.P.G.
Analysis of 38 formulations marketed by five companies indicated that the active ingredient contents of these products are within the range of 92 to 112%, for dicofol, and 107 to 142%, for tetradifon, of that declared. Manufacturing procedures for dicofol produce impurities related to DDT. The adoption of a prohibition directive in Europe requires that DDT-related impurities represent less than 1 g kg-1 of the dicofol content. Formulations manufactured before the prohibition directive contained these impurities at up to 575 g kg-1 of the dicofol in the formulation. Formulations manufactured after the directive contained these impurities at up to 7 g kg-1 of the dicofol in the formulation. Fewer impurities were detected in the more recent formulations, only o,o'-DDE, o,m'-DDE, o,p'-DDE, m,p'-DDE, p,p'-DDE, o,p'-chloro-DDT and p,p'-chloro-DDT were present. Eight of the 13 samples contained DDT-related impurities at less than 0.1 g kg-1 of the dicofol in the formulation. The major impurities found in formulations manufactured after the directive (in concentration terms) are non DDT-related manufacturing byproducts such as o,p'-dichlorobenzil.
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