Effect of glycerol on local and systemic carcinogenicity of topically applied tobacco condensate.

When glycerol was added to tobacco smoke condensate in acetone solvent, the topical carcinogenicity and the ability to produce epithelial hyperplasia in mice was reduced. Two doses of condensate were applied, combined with 2 concentrations of added glycerol. Age-standardized results show that glycerol reduced the incidence of tumours and malignant tumours and of hyperplasia in animals not developing skin tumours. The relative incidences of malignant tumours, benign tumours, hyperplasia and unaffected skin suggest that there is a sequential relationship (i.e. normal skin to hyperplasia to benign neoplasia to malignant neoplasia) which is impeded by glycerol. There was no systemic effect attributable to the condensate.