9. Since the exposure to nicotine from smokeless tobacco is similar in magnitude tonicotine exposure from cigarette smoking, the health consequences of smoking that arecaused by nicotine also would be expected to be hazards of smokeless tobacco use.Areas of particular concern in which nicotine may play a contributory or supportive rolein the pathogenesis of disease include coronary artery and peripheral vascular disease,hypertension, peptic ulcer disease, and fetal mortality and morbidity.
In epidemiology, which relies heavily on observational studies (that is, taking people as you find them), cause and effect is established by observing the same thing in a wide variety of settings until all but the suspected cause can be ruled out. The traditional approach is that given by Bradford Hill in his Principles of Medical Statistics (first published in 1937; 8th edition 1966). He would have us consider the strength of the association, consistency (observed repeatedly by different persons, in different circumstances and times), specificity (limited to specific sets of characteristics), relationship in time, biological gradient (dose response), biological plausibility (which is the weak link because it depends on the current state of knowledge), and coherence of the evidence.
Tobacco as a cause of lung cancer
Cigarette smoking is a major cause of stroke by increasing clotting factors in the blood,decreasing HDL cholesterol levels, increasing triglyceride levels, and damaging the liningof blood vessels.
Harmful Chemicals in Tobacco Products | American …
2. Recent studies of the effects of smokeless tobacco use ongingival and periodontal tissues have resulted in equivocal findings. While gingivalrecession is a common outcome from use, gingivitis may or may not occur. Becauselongitudinal data are not available, the role of smokeless tobacco in the development andprogression of gingivitis or periodontitis has not been confirmed.
Harmful Chemicals in Tobacco Products Tobacco smoke
3. Despite the complexities of tobacco smoke self-administration, systematic analysishas confirmed that the resulting addiction is similar to that produced and maintainedby other addictive drugs in both humans and animals. Animals can learn to discriminatenicotine from other substances because of its effects on the central nervous system. Theseeffects are related to the dose and rate of administration, as is also the case with otherdrugs of abuse.
Long-Term Glyphosate Use Effect on Wheat - The Farmer's Life
Today, the statistical community generally recognizes that these approaches are inappropriate in an era when anyone with a computer and a statistical software package can attempt to be his/her own statistician. "Cause & effect" must be among the first things that are addressed because this is what most people will use statistics for! Newspapers, radio, television, and the Internet are filled with claims based on some form of statistical analysis. Calcium is good for strong bones. Watching TV is a major cause of childhood and adolescent obesity. Food stamps and WIC improve nutritional status. Coffee consumption is responsible for heavens knows what! All because someone got hold of a dataset from somewhere and looked for associations. Which claims should be believed? Only by understanding what it takes to establish causality do we have any chance of being intelligent consumers of the "truths" the world throws at us.
Critics of conventional farming often decry the use of herbicides
A modern example is the link between smoking and lung cancer. Because is it impossible to conduct randomized smoking experiments in human populations, it took many decades to collect enough observational data (some free of one types of bias, others free of another) to establish the connection. Much of the observational evidence is compelling. Studies of death rates show lung cancer increasing and lagging behind smoking rates by 20-25 years while other forms of cancer stay flat. Smokers have lung cancer and heart disease at rates greater than the nonsmoking population even after adjusting for whatever potential confounder the tobacco industry might propose. However, when smoking was first suspected of causing lung cancer and heart disease, Sir Ronald Fisher, then the world's greatest living statistician and a smoker, offered the "constitution hypothesis" that people might be genetically disposed to develop the diseases and to smoke, that is, that genetics was confounding the association. This was not an easy claim to put to an experiment. However, the hypothesis was put to rest in a 1989 Finnish study of 22 smoking-discordant monozygotic twins where at least one twin died. There, the smoker died first in 17 cases. In the nine pairs where death was due to coronary heart disease, the smoker died first in every case.