Application of biochemical intake markers to passive smoking measurement and risk estimation.

Measurement of the dose received from passive smoking complements epidemiological approaches and may provide an alternative method of estimating risk. Non-smokers absorb measurable amounts of nicotine from breathing other people's smoke, and dose-response relationships are apparent. On the basis of the limited data so far available, the dose of nicotine received by the average British non-smoker may represent about 0.5% of that of the heavy cigarette smoker, ranging up to 2% in more heavily exposed individuals. The dose of carbon monoxide appears relatively greater, as does that of tobacco-specific nitrosamines. The situation with respect to tar is unclear, but nicotine may provide a better guide than does CO.