Interaction of environmental stress and hexachlorobenzene in the laboratory rat.

The effects of hexachlorobenzene (HCB) on the ability of male rats to adapt to a crowded environment were investigated. Eighty male rats were individually housed (1000 cm2 floor space per rat) and given either feed containing 250 ppm HCB or control feed. After 4 w, half of the rats from each diet group were transferred to smaller cages with four rats per cage (100 cm2 floor space per rat). After 1, 2, 4, 7, and 10 d, four rats each from the four treatment groups were sacrificed and organs removed for analysis. The HCB diet alone had no effect on the body weight of the rats. Crowding resulted in severe loss of body weight, an effect that was potentiated by the HCB diet. The HCB diet resulted in increased liver and kidney weight but had no effect on brain weight. Livers and kidneys of crowded rats weighed less than those of singly housed rats. Rats fed HCB then crowded had higher tissue residues of HCB and higher mortality than rats given HCB and not crowded or rats crowded but not given HCB.