Carcinogenic and mutagenic activities of milk from cows fed bracken fern (Pteridium aquilinum).

Carcinogenicity, toxicity, and mutagenicity of the milk of bracken fern (BF)-fed cows were determined. Four Brown Swiss cows were fed a BF-containing diet, and two cows were fed a normal hay-grain diet. The milk obtained was fed to rats as either fresh or freeze-dried powdered milk mixed with grain diet: 9 of 34 fed whole milk and 11 of 56 fed powdered milk diet developed small intestine, kidney, or urinary bladder carcinomas within 117 weeks, while 0 of 70 rats fed either whole or powdered milk from cows receiving a normal diet and 0 of 20 rats fed a basic grain diet displayed neoplasia of these organs. Six organic solvent extract fractions of milk were pre pared from BFor normal diet-fed cows. Diethyl ether and ethyl acetate fractions displayed the highest murine acute toxicity. The murine bladder carcinogenicity of prepared fractions was assessed by the pellet implantation tech nique. Diethyl ether fractions from milk of BF-fed cows induced bladder carcinoma in 10 of 24 mice compared with the corresponding fraction of normal diet-fed cows (3 of 19) or mice exposed to only the cholesterol vehicle (5 of 30, 6 of 40) (p < 0.01). Four organic solvent extract fractions of milk obtained from BFor normal diet-fed cows were prepared and tested for mutagenic activity in Salmonella typhìmurìum TA 98 and TA 100. The chloroform:methanol fraction from BF-fed cows demonstrated mutagenic activity for TA 100