Tobacco and Public Health - TCSC Indonesia

JONATHAN M. SAMET 305
also reported significantly increased risk for nonsmoking men married to wives who
smoked 1–19 cigarettes and 20 or more cigarettes daily (Hirayama 1984). In 1981,
Trichopoulos et al. (1981) also reported increased lung cancer risk in nonsmoking
women married to cigarette smokers. These investigators conducted a case–control
study in Athens, Greece, which included cases with a diagnosis other than for orthopedic
disorders. The positive findings reported in 1981 were unchanged with subsequent
expansion of the study population (Trichopoulos et al. 1983). By 1986, the
evidence had mounted, and the three synthesis reports published in that year concluded
that secondhand smoke was a cause of lung cancer (IARC 1986; National Research
Council 1986; US Department of Health and Human Services 1986).
In 1992, the US Environmental Protection Agency (US Environmental Protection
Agency 1992) published its risk assessment of secondhand smoke as a carcinogen. The
Agency’s evaluation drew on the toxicologic evidence on secondhand smoke and the
extensive literature on active smoking. A meta-analysis of the 31 studies published to
that time was central to the decision to classify secondhand smoke as a class A carcinogen,
i.e., a known human carcinogen. The meta-analysis considered the data from the
epidemiologic studies by tiers of study quality and location and used an adjustment
method for misclassification of smokers as never-smokers. Overall, the analysis found
a significantly increased risk of lung cancer in never-smoking women married to
smoking men; for the studies conducted in the United States, the estimated relative risk
was 1.19 (90 per cent CI: 1.04, 1.35).
The meta-analysis included pooled estimates by geographic region. The data from
China and Hong Kong were notable for not showing the increased risk associated with
passive smoking that was found in other regions (US Environmental Protection
Agency 1992). The epidemiologic characteristics of lung cancer in women in this
region of the world have been distinct with a relatively high proportion of lung cancers
in nonsmoking women. Explanations for this pattern have centered on exposures to
cooking fumes and indoor air pollution from coal-fueled space heating.
The 1997 meta-analysis by Law et al. (1997) included 37 published studies. The excess
risk of lung cancer for smokers married to nonsmokers was estimated as 24 per cent (95
per cent CI: 13 per cent, 36 per cent). Adjustment for potential bias, including misclassification
of some smokers as never smokers, and confounding by diet did not alter the
estimate. This meta-analysis supported the conclusion of the United Kingdom’s
Scientific Committee on Tobacco and Health (Scientific Committee on Tobacco and
Health & HSMO 1998) that secondhand smoke is a cause of lung cancer. More
recently, the International Agency for Research on Cancer (IARC 2002) reviewed more
than 50 studies, finding a similar increase in risk.
Secondhand smoke and coronary heart disease (CHD). Causal associations between
active smoking and fatal and nonfatal CHD outcomes have long been demonstrated
(US Department of Health and Human Services 1989). The risk of CHD in active
smokers increases with the amount and duration of cigarette smoking and decreases