Assessment of exposure to environmental tobacco smoke in nonsmoking pregnant women in different environments of daily living.

The relation between duration of recent exposure to environmental tobacco smoke and salivary cotinine concentration was assessed in a cross-sectional study conducted during the third trimester of pregnancy of 710 nonsmoking women attending a prenatal clinic in La Fe Hospital, Valencia, Spain, between September 1, 1989, and September 30, 1991. A structured interview questionnaire was used to obtain information on duration of exposure to environmental tobacco smoke in the last 3 days to four sources: 1) partner's smoking at home, 2) others' smoking at home, 3) others' smoking at work, and 4) others' smoking in vehicles and in indoor public places. Cotinine levels were determined in saliva samples obtained during interviews. The duration of exposure to any source was positively related to cotinine levels independent of exposure to the other sources (p < 0.05). Self-reporting of the duration of recent exposure was a proxy measure of the integrated dose as assessed by saliva cotinine concentrations. The results underline the need to consider sources of exposure other than partner's tobacco smoke and to assess them individually rather than as an unweighted summative measure.