Carcinogenicity of the fern Pteridium aquilinum collected from enzootic bovine haematuria-free hilly area in India

Chronic exposure in low doses to bracken fern (Pteridium aquilinum, family Pteridiaceae) has been associated with urinary bladder tumours and intermittent haematuria in bovines of hilly areas. In spite of the widespread distribution of the fern in the Himalayas and southern hills of the country, the disease is restricted to well-defined pockets. The possible reason for absence of the disease in other hilly areas even in presence of P. aquilinum could be due to lack of carcinogenic potential in the plant growing in such areas. In the present study, the fern was collected from an area where cases of bovine urinary bladder cancer and associated haematuria (enzootic bovine haematuria) have not been recorded. In these areas animals are left for grazing during rainy season. This fern was fed to guinea pigs for 30 months at the rate of 30% (w/w). The fern caused toxic and neoplastic changes in urinary bladders of the exposed animals. The incidence of tumours was 18.6%. The fern was found positive for the carcinogen ptaquiloside (3.74 ′ 0.6 mg/kg). The low level of ptaquiloside as compared to the values reported from elsewhere (0 to 9,776 mg/ kg; mean 1,257 mg/kg) and grazing during the period when grasses are abundant are perhaps the reasons for absence of the disease in such areas.