Cancer-Causing Fraction

In the intensive study of the relationship between cancer and cigarette smoking, it was clearly a breakthrough. Searching for the element in cigarette tar that causes cancers on mice (and, presumably, lung cancer in man), U.S. and Canadian scientists had narrowed the field to an identifiable fraction.

Last week Dr. Ernest L. Wynder of Manhattan's Sloan-Kettering Institute and the University of Toronto's Dr. George Wright told fellow experts in Atlantic City that they had separated the tar (by machine-smoking tons of cigarettes) into acid, alkaline and neutral portions. These were subdivided again until the researchers found the active cancer-causing fraction. It proved to be in the neutral portion. Isolated and applied to mice in the laboratory, it produced many cancers. Although it constitutes only 1 1/2% of the tar, the dangerous material contains many different chemical compounds, including a number known as aromatic polycyclic hydrocarbons. Next steps: identify the compounds, find out where they come from, and try to eliminate them from cigarettes.

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