The interaction between dietary concentrations of
vitamin A and PBB was evaluated in two experiments. In the first experiment, male weanling rats were used in a 2 X 3 factorial experiment. Concentrations of PBB were 0, 10, or 100 mg/kg of diet and diets were either
vitamin A-deficient or were supplemented with 3000 IU
vitamin A palmitate/kg of diet. In the second experiment the design was similar except that two
vitamin A-supplemented diets were used, one containing 3,000 IU/
vitamin A palmitate/kg of diet and the other 30,000 IU. Diets contained either 0 or 100 mg of PBB/kg. Clinical signs of
vitamin A deficiency and mortality occurred early in rats fed
vitamin A-deficient diets containing 100 mg of PBB/kg.
Vitamin A supplementation provided partial protection against decreased
weight gain associated with PBB. Decreases in thymic weight associated with PBB toxicosis were prevented by supplementation with
vitamin A. Massive enlargement of the common bile duct occurred in rats fed a
vitamin A-deficient diet containing 100 mg of PBB/kg. Histologically, this lesion consisted of extensive
hyperplasia. A significant decrease in
retinol concentrations in the sera was recorded in rats fed
vitamin A-deficient diets containing 100 mg of PBB/kg. Interaction between
vitamin A deficiency and PBB toxicosis affected
vitamin A metabolism as manifested by the appearance of appreciable amounts of
retinyl acetate in the liver
vitamin A profile. These results suggest an interaction between PBB toxicity and
vitamin A and emphasize the importance of nutritional factors such as
vitamin A in assessment of PBB toxicosis.