The disease detectives. Pt. 2, Epidemiology II; smoking and lung cancer.

The world is full of alleged dangers - mobile phones, landfill sites etc. Sir Richard Doll explains how he had no real idea of what caused lung cancer - cars? tar on the road? before smoking became most likely. Two methods epidemiologists use are 1) cohort studies, and 2) case/control studies. It can be difficult to establish that control groups are truly similar. Doll found as much as a fifty-fold increase in risk for smokers. Larry Beason has studied non-smokers to find out if industrial pollutants is associated with lung cancer. Doll is accused of downplaying the effects of industrial pollutants or pesticides. Attempts have been made to establish a connection between Agent Orange and medical problems in Vietnam veterans. Doll has supported the manufacturer. Epidemiologists argue about fluoride in drinking water causing increased cancer. The programme points out various pitfalls in epidemiology.