Smoking causes heart disease (increases risk up to 4 times).
Smoking causes lung diseases (bronchitis, emphysema).
Smoking causes lung cancer (increases risk 23 times in men, 13 times in women!).
Smoking causes cancer of:
- Blood or bone marrow (leukemia)
- Oral cavity (mouth)
- Pharynx (throat)
For a causal relationship, "there must be enough scientific evidence that smoking either increases the overall number of cases of the disease or makes the disease occur earlier than it otherwise would."3
The US Surgeon General uses these criteria as a foundation for a causal relationship:
- Do multiple high-quality studies show a consistent association between smoking and disease?
- Are the measured effects large enough and statistically strong?
- Does the evidence show that smoking occurs before the disease occurs?
- Is the relationship between smoking and disease coherent or plausible in terms of known scientific principles, biologic mechanisms, and observed patterns of disease?
- Is there a dose-response relationship between smoking and disease?
- Is the risk of disease reduced after quitting smoking?
2 CDC, Smoking and Tobacco Use, Health Effects of Cigarette Smoking
3 CDC, Smoking and Tobacco Use, How Do We Conclude That Smoking Is a Cause of Disease?