I. Production of skin tumors in mice with oxidation products of aliphatic hydrocarbons

REAL and progressive increase in the fre-A quency of lung cancer has been reported in many regions throughout the world.1, 8, 18, 23A striking feature of these reports is the observation of a consistently higher mortality rate from lung cancer in urban areas when contrasted with rural areas.2,7,13,25Atmospheric pollution in urban areas has been suggested as a significant factor in this difference in incidence.1'. 25In an attempt to measure the significance of atmospheric pollution as a possible determining factor in the urban-rural lung-cancer difference, chemical analysis and bioassay of atmospheric pollutants and pollution sources for carcinogenic materials have been undertaken by several investigators.5~6 Leiter and his co-workers19+ 2o produced sarcomas in C57 black mice with tars extracted from the atmosphere of several large American cities.Waller demonstrated the presence of benzpyrene in the atmosphere of several large English cities. Atmospheric extracts and diesel-exhaust products were used by Clemo, Miller, and Pybus for the production of skin cancers in mice.T h e presence of 3,4-benzpyrene in the atmosphere of Los Angeles, and the production of skin cancers in C57 black mice with atmospheric extracts have been reported from this laboratoIy.17A comprehensive review of published reports relating to the presence of carcinogenic materials in the atmosphere and at pollution sources indicates that all are p imarily concerned with the demonstration anti bioassay ol aromatic polycylic hydrocarbons, including the potent carcinogen, 3,4-benzpyrene.:3z