Possible polychlorinated biphenyl poisoning in rhesus monkeys (Macaca mulatta)

In 1967-68 rhesus monkeys that had been held in new pens for a month or more developed a chronic disease with high mortality. The principal postmortem findings were focal necrosis of the liver and hyperplasia of bile duct epithelium, invasive gastric mucosal metaplasia, and squamous metaplasia of the sebaceous glands. The monkeys were probably poisoned by polychlorinated biphenyls (PCBs), because the pathologic changes were identical with those occurring after experimental feeding of PCBs to monkeys, and because PCBs were found in the livers of the dead animals. The source of the contaminant was not identified.