Bracken carcinogenicity.

The study of bracken carcinogenicity affords an interesting example of the close alliance, with mutual benefit, between the work of veterinarians in the field and experimental research. On the one hand was the condition found in many parts of the world of bovine enzootic haematuria with uncertain aetiology and, on the other, the investigations conducted on the acute radiomimetic cattle bracken poisoning under laboratory conditions. The two have led to the recognition of the long term cancer dangers of bracken consumption and the vulnerability of a wide variety of species of animals. In these the types of tumour vary to include many organs other than the bladder, such as the gastrointestinal tract and blood forming tissues. Work on the search for the chemical compounds involved is described, together with the possible hazards, both mutagenic and carcinogenic, on an environmental basis.