title: Lung cancer and passive smoking: association of an artefact due to misclassification of smoking habits?
abstract: 1775 subjects were asked about their current use of tobacco products or nicotine chewing gum. 1537 provided a sample of saliva for cotinine analysis. Of 808 who claimed not to be users of such products, 20 (2.5%) had cotinine values above 30 ng/ml, suggesting their self-reports were false. In another study, 540 subjects were interviewed on two occasions. 10% of subjects claiming on one occasion never to have smoked made inconsistent statements on the other occasion. A third study showed a strong tendency for smokers to marry smokers. Bias caused by misclassification of smoking habits coupled with between-spouse smoking habit concordance can completely explain reported apparent excesses in lung cancer risk in non-smokers married to smokers.
mesh_terms: D002638:Chewing Gum; D003367:Cotinine / Q000032:analysis; D005260:Female; D006801:Humans; D007407:Interviews as Topic / Q000592:standards; D008175:Lung Neoplasms / Q000209:etiology*; D008297:Male; D008393:Marriage; D012106:Research; D012107:Research Design; D012306:Risk; D012463:Saliva / Q000032:analysis; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D002638:Chewing Gum; D014028:Tobacco Smoke Pollution; D003367:Cotinine