Eight esters of methanesulfonic acid were applied in conjunction with a short course of croton oil applications to the dorsal skin of separate groups of mice.
Four of the test substances, namely, allyl methanesulfonate, 1,4-dimethanesulfonoxy-2-butyne (CB2058), and the cis and trans isomers of 1,4-dimethanesulfonoxy-2-butene, in conjunction with croton oil, caused significantly more papillomas than did treatment with croton oil only. Mice treated with 1,4-dimethanesulfonoxy-2-butyne and croton oil were kept under observation after the end of treatment; in these, five malignant tumors arose.
Only one of the substances, 1,4-dimethanesulfonoxy-2-butyne, has so far been tested for carcinogenicity on the skin: repeated applications without croton oil gave rise to two papillomas.
None of the test substances when applied to the dorsal skin increased the incidence of lung tumors.
No correlation was observed between tumor-initiating activity and the production of epidermal hyperplasia.
The cost of this research was partly defrayed out of a Block Grant from the British Empire Cancer Campaign.