Smoking--Cancer Link Reported By Harvard Scientists

Two research scientists from the Graduate School of Public Health have discovered a radioactive element in cigarette smoke which may be the direct cause of lung cancer.

Dr. Edward P. Radford, associate professor of Physiology, and Mrs. Vilma Rose Hunt '58, research associate in Physiology, released late yesterday a preliminary report which names polonium 210 as the element in cigarette smoke which produces cancer. This conclusion is based on studies they have been conducting since last August.

For a man smoking two packs of cigarettes a day for 25 years, they say, polonium deposited in the bronchial linings may deliver a radiation dose at least seven times the normal radiation exposure of non-smokers. It has been known for many years that ionizing radiation can produce cancer in man, but this report is the first to suggest that radic-isotopes in cigarettes are involved in the production of lung cancer.

Polonium, the researchers maintain, occurs naturally in the tobacco leaf, since it is absorbed through the roots of all green plants from the soil. It is also absorbed to a lesser degree from "natural fallout" in the atmosphere.

Vaporization of polonium occurs at the burning temperature of the cigarette (1112 to 1472 degrees Fahrenheit), and it is carried into the lungs by attaching itself to the inhaled smoke particles, according to the report's findings. Most of it is eventually taken up by "scavenger cells" and carried over the bronchial lining to the throat.

Background exposure to radiation is about five rem for a non-smoker, and for the heavy smoker about 36 rem. Even this estimate "is probably conservative, and the dose could be 100 rem or more," when the additional radioactive effect of lead 210 and bismuth 210 absorption is included, the report says.

Four American brands of cigarettes, two of them with filters, were used in the laboratory research. With equipment devised to artificially puff the smoke at the rate of one puff every 50 seconds for six minutes, slightly slower than the smoking of most humans, little or no difference between the filters and non-filters was noted.

The only way to relieve the danger of lung cancer from cigarette smoking is to remove the polonium, Radford said last night. He suggested that the tobacco companies would find it "economically feasible to treat tobacco leaves chemically" to remove the polonium.

He emphasized, however, that even removing the polonium would not hinder the non-cancer effects of smoking mentioned in the recent government report, such as increased heart disease and bronchitis.

There is reason to believe, Radford said, that the polonium content of pipe and cigar tobacco is about the same as in cigarettes, but that the cancer rate is lower for pipe and cigar smokers since they do not inhale as much. However, he added that cancer of the mouth and esophagus is about as frequent in all smokers.

The researchers findings to date are reproduced in full in this month's issue of Science magazine. Radford and Mrs. Hunt plan to continue their studies of all radioactive elements in tobacco and of the other effects of polonium on the tissue of smokers.

A non-smoker himself, Radford last night labelled smoking as "a messy, expensive habit," which is also extremely dangerous. "While I have no plans to become a crusader against smoking," he said, "I strongly urge everyone to stop at once."