Carcinogenicity in mice of some fatty acid methyl esters. 2. Peroral and subcutaneous application

Two fatty acid methyl esters, methyl oleate and methyl 12-oxo-trans-10-octadecenoate, have been tested for carcinogenicty by oral and subcutaneous administration in ST/a mice of both sexes. A positive effect of methyl oleate could not be assessed, while the results pointed to a promoter effect of methyl oxo-octadecenoate. Given in the diet, this compound increased the incidence and number of forestomach papillomas within 83 weeks after initiation by 4-nitroguinoline 1-oxide. Repeated injections of methyl oxo-octadecenoate in the inguinal area resulted in 2 local sarcomas in a group of 20 females which had previously received skin initiation by 7, 12-dimethylbenz [alpha] anthracene in the neck. In no other animal group did sarcomas appear at this location within the observation period of 2 years. An influence by the injected methyl esters on the initiated skin carcinogenesis was possibly, but weakly, present. The need for more extensive experiments is stressed, especially with a view to the possible carcinogenic hazards involved in dietary intake of oxygen-containing derivatives of oleic acid.