Experiments were conducted to determine the effect of bentonite and nonnutritive dietary polymers on toxicity and metabolism of T-2 toxin in rats. Male weanling rats were fed diets containing 5% bentonite, anion exchange resin, cation exchange resin or vermiculite-hydrobiotite. Each diet was fed with and without 3 micrograms T-2 toxin/g of feed for 2 wk. Bentonite and anion exchange resin were the treatments most successful at overcoming growth depression and feed refusal caused by T-2 toxin. Subsequent experiments tested bentonite and anion exchange resin at 0, 2.5, 5.0, 7.5 and 10% of the diet. Bentonite fed at 10% was the most effective treatment at overcoming feed refusal and growth depression. Rats were fed 0, 5, 7.5 or 10% bentonite for 2 wk and then dosed with [3H] T-2 toxin. Urine and feces were collected for 21 h after dosing and tissues were excised for determination of residual 3H. Feeding bentonite had little effect on the fraction of the dose excreted in the urine. Significant increases in fecal excretion of 3H were shown, when the feeding of 5, 7.5 or 10% bentonite was compared with the casein-based, semi-purified control diet. Dietary bentonite had no effect on residual 3H in liver or kidney, but all concentrations of bentonite tested reduced residual 3H in muscle. More 3H was found in the digesta in the small intestine and in the wall of the intestinal tissue when rats fed 5% bentonite were compared with the controls. Intestinal transit time for rats fed bentonite diets was reduced compared with that of the controls as indicated by chromic oxide marker studies.(ABSTRACT TRUNCATED AT 250 WORDS)