The Chlorinated Hydrocarbon Content of Milk from Cattle Sprayed for Control of Horn Flies

Abstract

Cattle at 11 commercial dairies in Kerr and Gillespie counties, Texas, were sprayed 4-6 times for control of horn flies [Siphona irritans], with water suspensions of DDT, TDE, methoxychlor, toxaphene and chlordan, all at concns. of 0.5%. DDT was also used at 0.25%. The amts. of organic Cl found in the milk from cows sprayed with all except DDT and TDE were too small to be regarded as definitely indicating the presence of the insecticides. TDE was detd. colorimetrically and also was calculated from chlorine detns. By the colorimetric procedure maximums of 1.2 and 1.1 ppm. of TDE were found in the milk; and maximums of 2.0 and 1.5 ppm. of DDT were found in the milk from the dairies using sprays of 0.5 and 0.25%, respectively. The average DDT content of the milk for approx. 7 mos. was 0.5 ppm. in the 2 dairies using the 0.5% concn. and 0.3 ppm. in the 2 using the 0.25% concn.