Estimation of smoke dosage and mortality of non-smokers from environmental tobacco smoke.

This paper shows how biochemical markers can be used to estimate smoke intake from passive smoking to complement epidemiological studies on the health risks and mortality to non-smokers. Using data from slow nicotine infusions given over 1 h, we estimated that the nicotine intake from passive smoking averages about 0.014 mg/h among urban non-smokers leading their usual daily lives. This compares with 0.23 mg/h in a smoke-filled public house, 0.36 mg/h during maximum exposure in an unventilated room, and 1.0 to 1.4 mg nicotine per cigarette taken in by active smokers. Data from several studies on urinary nicotine concentrations and those of cotinine in blood, urine and saliva were collated. The results show that the concentrations in non-smokers averaged about 0.7% (for nicotine) and 0.6% (for cotinine) of the levels found in smokers. From this we estimate that the mortality from passive smoking is about 1000 non-smokers per year in Britain and about 4000 per year in the United States, assuming that the relation of dose to risk is linear.