Abstract

The release of 1: 1: 1 trichloro-2: 2 bis- (p. -chlorophenyl)-ethane ( p - p' * DDT for civilian consumption with the cessation of hostilities and its extensive use in agriculture and horticulture has given rise to a number of problems, many of which are still a matter of speculation and await solution. The voluminous literature available on the subject, is sometimes vague and contradictory. For example, the great stability and extraordinary persistence of DDT are well known (Fleck, 1944, Fleck and Haller, 1945, Balban and Sutcliffe, 1945). Cages treated with solution of DDT in kerosene killed flies even after a period of 8 1/2 months (Lindquist, 1944), and one application of DDT was found sufficient to prevent an infestation of plums by the Japanese beetle for one full season (Fleming, 1944). Despite this accredited stability Gunther (1945) reported that deposits of DDT lost their toxicity in less than 2 1/2 months under the climatic conditions of California where the shade temperature reached 125 deg * F Whether this loss is due to volatilization of the insecticide or to some other factors like absorption by the tissues or drying up of the films and dropping off is not known with any degree of certainity. Apparent contradictions of this nature may be attributed to the suddenness with which DDT has risen to prominence and to the fact that there is as yet no satisfactory method of estimating the p / (p') * DDT content (the insecticidally important isomer) of DDT samples.

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