MASS BALANCE OF POLYCHLORINATED-BIPHENYLS AND OTHER ORGANOCHLORINE COMPOUNDS IN A LACTATING COW

A contaminant mass balance was conducted of a lactating cow in its natural state. PCBs, HCHs, DDE, DDT, HCB, and several other chlorinated substances were investigated. It was found that virtually all of the cow's exposure was through feed. The contaminant absorption in the cow and hence the carry-over rate of persistent compounds was found to be a function of K(ow), with approximately constant values up to a log K(ow) of 6.5 and thereafter rapidly decreasing absorption with increasing lipophilicity of the contaminant. The key to PCB persistence in the cow was the 4,4' substitution pattern. The 2,3,5 substitution was a less effective hindrance for PCB metabolism.