Tobacco Documents Online

As we have seen, over the years the tobacco industry spent some time and effort casting about for something other than tobacco products that could be blamed as the cause of lung cancer in smokers. In past postings we have seen that they proposed, for example, the "Carotene Hypothesis" (the theory that an excess of dietary carotene causes lung cancer), the "Reverse Hypothesis" (which proposed that lung cancer causes smoking), and the "Constitutional Hypothesis" (which proposed that something in a person's personality predisposes him or her to get lung cancer). The author of today's document brings up yet another theory closely related to the "Constitutional Hypothesis," called the "Unidentified Common Factor theory" (or U.C.F. for short). The "Unidentified Common Factor" theory held that some unknown characteristic shared by a certain group of people predisposes them to both smoking and lung cancer.

The author states that

"...there are some eminent scientists who have suggested that there may well be a common factor which leads people to smoke and to develop lung cancer through a causal mechanism which does _not_ involve smoking...Thus the late Sir Ronald Fisher, who was one of the world's greatest geneticists, suggested that such a factor might exist in the type of genes a person inherited...Eysenck (who is a psychologist), Burn, (a pharmacologist) and Berkson (a medical statistician) have all suggested quite independently that heavy smokers have less resistance to lung cancer, perhaps because they live at an accellerated rate...[or] perhaps because they are less careful of their health, [or] perhaps because they are less biologically self-protective, and that some personal characteristic such as these causes the statistical association between smoking and lung cancer."

Yet in the same paper, the writer discusses the unliklihood of the U.C.F. Theory:

"It is not difficult to build up a hypothesis about an Unidentified Common Factor that fits all the known statistical facts about smokig and lung cancer. It can also be argued that many scinetific theories are developed simply by building up a hypothesis that fits all the observed facts. But is it inherently likely that an Unidentified Common Factor with all these very detailed characteristics really exists, waiting to be discovered as a result of some lucky experiment? Speaking in terms of probability...all I can say is that it is most improbable that such an Unidentified Common Factor exists. Finally, if such a Factor were to exist, it would only make the hypothesis that smoking causes lung cancer unnecessary: it would not prove that the smoking hypothesis was false."

The rest of this paper is also full of insights into how people inside the tobacco industry think about public health (or not). For example, near the beginning of the paper, the speaker takes an interesting viewpoint about the importance of the number of people dying from cigarette use:

"The vital statistics I would like you to bear in mind are 7, 57, 139 and 227...There is no glamour about these figures. They are the death rates per 100,000 per year from cancer of the lung of men who were nonsmokers (they are the 7), men who smoked 1-4 cigarettes daily (they are the 57), men who smoked 15-24 cigarettes daily (they are the 139) and men who smoked 25 or more cigarettes daily (they are the 227)...These four vital statistics are basically the reason why we are here to-night. They are the reason why the tobacco manufacturers in this country have spent over 25m to date on smoking and health reasearch... These vital statistics are really vital. They threaten the life of the tobacco industry in every country of the world."