Medicine: Something in the Air

It was all very well to show that there is something in cigarette smoke that can cause lung cancer, but the proof of this (TIME, Nov. 30) still left a further question unanswered. Why do city dwellers seem to get more lung cancer than folk down on the farm with the same smoking or nonsmoking) habits? Could it be something in the air?

The answer is yes, say four University of Southern California researchers, headed by Dr. Paul Kotin, in the Archives of industrial Hygiene and Occupational Medicine. From samples of Los Angeles air (collected on both smoggy and clear days), the experimenters filtered out the chemicals. They painted the resulting goolon the backs of black mice. In little more than a year, 29% of the surviving mice developed malignant tumors. From gasoline-engine exhausts the researchers prepared a similar slime: 26% of the mice got cancer. Identical mice, under the same conditions but unpainted, showed not a single tumor.