| Abstract: | Marked seasonal changes in the BHC content of butter in Northern Ireland are reported. Levels of alpha-BHC rise to a maximum of between 0.5 and 0.9 mg/kg on a fat basis in January and February, falling to between 0.02 and 0.04 mg/kg in late summer and early autumn. The use of veterinary preparations containing technical BHC for the control of lice infection in the winter months would appear to be responsible for such fluctuations. Maximum BHC contamination of milk in January and February probably arises by direct ingestion or skin absorption of externally applied BHC and subsequent transfer from the bloodstream to the milk fat. A later smaller contamination peak in the April/May period is probably due to mobilisation of BHC stored in the body fat of the animals during the first weeks after parturition. |
