On the Nature of Evidence and 'Proving' Causality: Smoking and Lung Cancer vs. Sun Exposure, Vitamin D and Multiple Sclerosis.

ABSTRACT: If environmental exposures are shown to cause an adverse health outcome, reducing exposure should reduce the disease risk. Links between exposures and outcomes are typically based on 'associations' derived from observational studies, and causality may not be clear. Randomized controlled trials to 'prove' causality are often not feasible or ethical. Here the history of evidence that tobacco smoking causes lung cancer-from observational studies-is compared to that of low sun exposure and/or low vitamin D status as causal risk factors for the autoimmune disease, multiple sclerosis (MS). Evidence derives from in vitro and animal studies, as well as ecological, case-control and cohort studies, in order of increasing strength. For smoking and lung cancer, the associations are strong, consistent,

SUBMITTER: Lucas RM 

PROVIDER: S-EPMC6121485 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature