Measuring infant exposure to environmental tobacco smoke.

Methods to measure infant exposure to environmental tobacco smoke (ETS) are needed to identify infants at highest risk for ETS-related health problems. The purpose of this study was to validate measures sensitive to changes in levels of infant exposure to ETS and to develop a predictive model of infant exposure to ETS. Fifteen infants of smoking mothers were followed from birth to 6 weeks of age. Exposure to ETS was measured by using a smoking habits questionnaire, cigarette "butt" collection, infant urine nicotine and cotinine levels, and ambient nicotine (personal air monitors). The 24-hour cigarette butt collection was the best predictor of acute (adjusted r2 = .83) and chronic exposure (adjusted r2 = .47) measured by infant urinary nicotine and cotinine levels when the infants were 2 weeks of age. Including scores on the smoking habits questionnaire and ambient nicotine levels increased the adjusted r2 to .88 and .61, respectively.