Residues of hexachlorobenzene in subcutaneous and butter fat of cattle

Abstract

The effects of four dietary levels of hexachlorobenzene (HCB) on the accumulation and disappearance of subcutaneous fat residues of HCB were examined in steers. The rate of rise of HCB in the fat increased with dose rate, a level of 98.5 mg kg -1 being reached after ten weeks in steers fed 21 6 mg day -1. Animals fed 36 and 6 mg day -1 recorded average levels of 16.25 and 3.1 mg kg -1 respectively. The residues decreased exponentially; the average half life was 10.5 weeks. Animals maintained on starvation rations for a period of four weeks displayed a reduced rate of elimination of HCB residues from their fat than for animals fed normally. In an experiment with milking cows dosed with four levels of dietary HCB, the uptake of HCB in the butter fat was approximately linear, reaching levels of 0.36, 4.37 and 16.7 mg kg -1 for cows dosed with 1, 6 and 36 mg day -1 respectively. The degradation curves were exponential ; the half life ranged from 4 to 8 weeks with a mean of 6.4.