IN THE COURSE of its struggle to find acceptable cuts in the federal budget, the Senate Budget Committee flirted for a while the other day with the idea of cutting the $200 million the federal government pays each year in tobacco price supports -- and then rejected it. Sen. Henry Bellmon had proposed the cut, noting that there is some inconsistency in the government's spending billions to fight cancer, on the one hand, while supporting tobacco production, on the other.

It would have been one thing to fight the proposal strictly on grounds that so sudden and summary an act -- as distinct from a more gradual planned withdrawal -- would create terrible economic hardship. But leaping to the defense of one of his state's major indusries, Sen. Ernest Hollings asserted that there is no "conclusive proof" that smoking and lung cancer are related. And, even making allowanace for a senator's natural defense of his home state's interests, this is going too far. After 40 years of medical studies showing the causal relationshiop between smoking and cancer -- about which there remains not a shred of scientific doubt -- one wonders what kind of proof would satisfy Sen. Hollings and the leaders of the tobacco industry who are often heard to utter the same sentiment. What more evidence can possibly be needed to impeach smoking once and for all?

Just to set the record straight, here is some of what is currently known about smoking and health. Smokers as a group have a 70 percent increased risk of death over non-smokers of the same age. Heavy smokers (two packs a day or more) have a 100 percent increased risk -- that is, they are twice as likely to die at a given age as non-smokers. Mortality rates for smokers are directly proportional to both duration (how long they have smoked) and dose (how much), but the rates are higher for those who start at a young age compared with those who start later in life. f

With regard to general ill-health, smokers are more frequently afflicted with chronic conditions -- including bronchitis, emphysema, sinusitis, peptic ulcer disease and others -- than non-smokers. They also suffer higher rates of acute disease, such as influenza. Male smokers report 33 percent and women 45 percent more workdays lost than non-smokers.

Contrary to popular belief, lung cancer is not the chief cause of death from smoking; coronary heart disease is. Arteriosclerosis and other vascular diseases are also increased. Smoking is unequivocally a cause of cancer of the lung, of the larynx, of the mouth and of the esophagus. It is also significantly associated wiith cancers of the bladder, kidney and pancreas. Maternal smoking increases the incidence of fetal death and of death just before or after the time of birth. It lowers birth weights and may affect the physical and mental development of the child for many years.

On top of all this, smoking also acts synergistically wiith many other risks: in other words, the risk of two factors' acting together (for example, smoking and hypertension) is greater than the sum of the two individual risks. Occupational exposures -- in the chemical industry, mining, uranium, rubber, textiles and more -- and smoking are especially dangerous. For example, asbestos workers who smoke have nearly 100 times greater risk of getting lung cancer than their co-workers who don't smoke. Synergistic effects also occur closer to home -- with alcohol, oral contraceptives and saccharin.

We can close with one final note of optimism: most of these health risks decline in former smokers and continue to fall as the years of non-smoking increase. After 15 years of cessation, the mortality risk of former smokers is about the same as that of non-smokers. That's what people who smoke should be hearing about -- not that there is no "conclusive proof" of smoking's harm.