U.S. Govt. Classifies Environmental Tobacco Smoke As A Known Human Carcinogen [01/31-8]
National Toxicology Program
Environmental tobacco smoke is known to be a human carcinogen based
on sufficient evidence of carcinogenicity from studies in humans that
indicate a causal relationship between passive exposure to tobacco
smoke and lung cancer. Some studies also support an association of
environmental tobacco smoke with cancers of the nasal sinus (CEPA
1997).
Evidence for an increased cancer risk from environmental tobacco
smoke stems from studies examining nonsmoking spouses living with
individuals who smoke cigarettes, exposures of nonsmokers to
environmental tobacco smoke in occupational settings, and exposure to
parents’ smoking during childhood (IARC 1986, EPA 1992, CEPA
1997). Many epidemiological studies, including large population-based
case-control studies, have demonstrated increased risks for developing
lung cancer following prolonged exposure to environmental tobacco
smoke. A meta-analysis found an overall increase in risk of 20% for
exposure to environmental tobacco smoke from a spouse who smokes.
Exposure to environmental tobacco smoke from spousal smoking or
exposure in an occupational setting appears most strongly related to
increased risk.
Exposure of nonsmokers to environmental tobacco smoke has been
demonstrated by detecting nicotine, respirable smoke particulates,
tobacco specific nitrosamines, and other smoke constituents in the
breathing zone, and by measurements of a nicotine metabolite
(cotinine) in the urine. However, there is no good biomarker of
cumulative past exposure to tobacco smoke, and all of the information
collected in epidemiology studies determining past exposure to
environmental tobacco smoke relies on estimates that may vary in their
accuracy (recall bias). Other suggestions of systematic bias have been
made concerning the epidemiological information published on the
association of environmental tobacco smoke with cancer. These include
misclassification of smokers as nonsmokers, factors related to lifestyle,
diet, and other exposures that may be common to couples living
together and that may influence lung cancer incidence, misdiagnosis of
cancers that metastasized from other organs to the lung, and the
possibility that epidemiology studies examining small populations and
showing no effects of environmental tobacco smoke would not be
published (publication bias).
Click here* to view the Environmental Tobacco Smoke portion of the 11th Report on Carcinogens
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Click here to view the entire 11th Report on Carcinogens
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