There’s nothing new about the idea that smoking is bad for you, but it took decades of scientific research before it was widely accepted. Kevin McConway (pictured right) explains
Back in 1604, King James I of England wrote: “Smoking is a custom loathsome to the eye, hateful to the nose, harmful to the brain, dangerous to the lungs.” However, this sort of writing didn’t have much impact. By the end of the Second World War, in Britain about 80 per cent of men were regular smokers, and most smoked cigarettes.
During the first half of the twentieth century, lung cancer had risen from a relatively rare disease to a major cause of death. This had occurred alongside the rise in popularity of cigarettes, leading some experts to suggest that cigarette smoke was a cause of lung cancer. However, there were several other current theories on the causes of lung cancer, including the rise of motor transport. A few scientific studies had found some evidence of a link between smoking and lung cancer, but generally their results had little impact. After all, the pattern of cause and effect isn’t entirely clear. Not everyone who smokes gets lung cancer.
pioneers Doll and Hill
The beginning of a major worldwide change in attitude goes back to 1950, when five studies were published giving clearer evidence of a link between smoking and lung cancer. One was carried out by Richard Doll and Austin Bradford Hill. They found individuals with lung cancer from four hospitals in the UK, and other individuals who were patients admitted to the hospitals for different reasons. They asked about their smoking habits. Unsurprisingly, given how common smoking was at the time, a large majority of the individuals in both groups were smokers; but this proportion was much larger in the group who had lung cancer.
Doll and Hill believed that the reason was that smoking caused lung cancer. However, other scientists pointed out that such findings were consistent with other explanations, for example that some other factor (such as air pollution) caused people to smoke, and, independently, also caused them to have lung cancer.
the 40,000 doctor study
Despite the doubts, these studies provided a spur to further, more persuasive, work. The researchers followed up groups of people over years, recording their smoking habits and their health. In one such study, again by Doll and Hill, the group followed up were British doctors, over 40,000 of them. Such a study takes time, because the effects of smoking on lung cancer take time. But even after two and a half years this study had demonstrated large differences in lung cancer death rates between smokers and non-smokers. It found, further, that smokers were more likely to die of heart disease. An even larger American study followed up 190,000 men and provided similar findings.
Again the results were criticised. People did not dispute that the studies had shown an association between smoking and lung cancer, but tried to point out that this association might not be one of cause and effect. However, further research of different kinds eventually dismissed such objections. Gradually the hypothesis that cigarette smoking causes lung cancer became more widely accepted.
tipping public opinion
Two major reports summarising the evidence, by the Royal College of Physicians of London (1962) and the US Surgeon General (1964), strongly took the line that smoking causes lung cancer. Arguably it was these reports that swung medical, and eventually public, opinion behind the view that smoking is seriously harmful to health.
Research on smoking and health has continued since the 1960s. Although many of the deaths linked to smoking are due to lung cancer, many more of them are not. Evidence for a link between smoking and heart disease is now very strong. It is generally accepted nowadays that smoking increases one’s chances of contracting something like 50 different diseases.
The effect of life-long smoking on health is now known to be considerably more severe than the early studies indicated. However, it still took well over a decade after the publication of the first major studies, and much more research, before it was widely accepted that smoking is really bad for you.
Kevin McConway is a Professor of Applied Statistics at The Open University.
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Comments
Ahhh but we are forgetting how addictive nicotine is! Once people realise they are hooked to their packet of 20 ciggies its too late...lets face it, smoking is a legalised drug.
It's funny how research shows it to be bad for your health - and the cigarette boxes even declare "smoking kills" - yet people continue to do it. Would we drink a bottle of poison if it said "drink this and you'll die"? Probably not. I guess because smoking kills us slowly we don't think about it until it's perhaps too late. For me, the more immediate effects of smoking are just as off-putting as the health risks - it smells, is incredibly anti-social and also a very expensive habit.
It's thought provoking to be reminded about some of the research behind what is now widely known about the damaging effects of smoking. I still find it difficult to grasp that it took so long for such compelling findings to be accepted. We can understand this to some extent in terms of the fact that as consumers we often resist bad news. Let's hope that we learn the lessons about obesity and its impact on health sooner.