3.
Environmental Tobacco Smoke
Authors
This chapter was prepared by Peter Allard, of Scott, Allard, and Bohannan, Inc.
Introduction
Environmental tobacco smoke (ETS) is a mixture of the smoke given off by the burning end of cigarettes, pipes, and cigars, and the smoke exhaled by smokers. It is a known human carcinogen, or Group A carcinogen under the EPA classification system.
ETS contains as many as 4,000 chemical substances. Over 40 of these substances cause cancer in humans and animals. Many are strong respiratory irritants.
The health risk from inhalation of tobacco smoke includes non-smokers who inhale ETS. The Surgeon General and National Research Council estimate a relative risk of lung cancer of approximately 1.3 for a non-smoker living with a smoker instead of with a non-smoker.
Evidence also suggests a possible association between ETS exposure and an increased risk of heart disease in non-smokers (NIOSH, 1991).
ETS exposure has been linked to diminished pulmonary function and more frequent exacerbations of asthma in children ("Association Between Exposure," 1993).
According to the EPA, ETS is responsible the following:
o Approximately 3,000 lung cancer deaths annually among U.S. non-smokers
o 150,000 to 300,000 lower respiratory tract infections annually in children under 18 months old
Resulting in 7,500 to 15,000 hospitalizations each year
o Increased numbers of episodes and severity of symptoms for 200,000 to 1,000,000 asthmatic children
o The development of new cases of asthma in children
o Other significant effects on the respiratory health of non-smoking adults and children, including coughing, phlegm production, wheezing, chest discomfort, and reduced lung function (EPA, 1992)
Several other risk assessments for ETS show that never-smokers have obtained similar lung cancer death rates.
o A 1986 study by the National Research Council estimates that of the lung cancer deaths reported in 1985, there were 2,830 attributable to ETS.
o Wells (1985) estimates that approximately 3,000 lung cancer deaths were reported in 1985 among people who never smoked, but whose deaths occurred as a result of ETS exposure.
o Repace and Lowry (1990) estimate that approximately 5,000 lung cancer deaths reported in 1988 among never-smokers and ex-smokers were due to ETS exposure.
o The American Medical Association (1994) estimates that ETS causes the following conditions in the U.S. annually:
8,000 to 26,000 new asthma cases in children
5,000 deaths due to sudden infant death syndrome (SIDS)
15,000 to 19,000 deaths from heart disease
Prorating the EPA annual rate of 3,000 lung cancer deaths, and the American Medical Association annual rate of 15,000 to 19,000 heart disease deaths from ETS exposure to the non-smoking population (1990 Census) and adult non-smokers in Arizona, yields the results shown in Table 3.1 on the following page. ADHS data were used for Arizona SIDS deaths.
Table 3.1 Cancer & Heart Disease Deaths from ETS, U.S. and Arizona, 1990
---------------------------------------------------------------------------- | Category | United States | Arizona | ============================================================================ | Population, 1990 Census | 248,709,873 | 3,665,228 | ---------------------------------------------------------------------------- | Fraction of Adult Smokers | 0.26 | 0.207 | ---------------------------------------------------------------------------- | Number of Adult Smokers | 64,664,566 | 758,702 | ---------------------------------------------------------------------------- | Number of Adult Non-Smokers | 184,045,307 | 2,906,526 | ---------------------------------------------------------------------------- | ETS Lung Cancer Deaths/Year | 3,000 | 35 | ---------------------------------------------------------------------------- | Excess Lifetime Cancer Risk for Non- | 1.6 x 10-5 | 1.2 x 10-5 | | Smokers | | | ---------------------------------------------------------------------------- | ETS Heart Disease Deaths/Year | 16,000 to 19,000 | 189 to 239 | ---------------------------------------------------------------------------- | Sudden Infant Death Syndrome (SIDS) | 5,000 | 11 | ----------------------------------------------------------------------------
The Arizona population fraction of adult smokers of 0.207 is taken from the ADHS's Behavioral Risk Factor Surveillance data for 1993.
The excess lifetime cancer risk assumes that the annual rate of new cases of lung cancer caused by ETS is equal to the lung cancer death rate due to ETS exposure.
Given this assumption, the Committee calculated that 38 ETS lung cancer deaths occur in Arizona each year.
A similar proportional calculation was used to estimate deaths from heart disease.
Since smokers are not included in the EPA mortality estimate, the non-smoking census population is used to calculate the estimate of excess lifetime cancer risk for non-smokers.
The Committee's calculations and the EPA estimate of ETS lung cancer deaths do not separate occupational from total ETS exposure, and theoretically attribute an undetermined number of deaths due to occupational exposure to ETS.
The EPA estimate of 3,000 ETS lung cancer deaths per year includes:
o Approximately 1,500 female, and 500 male never-smokers
o 1,000 former smokers of both sexes
These 3,000 lung cancer deaths from ETS represent 2.1% of the American Cancer Society 1991 total of 143,000 lung cancer deaths:
o 92,000 males
o 51,000 females
Estimates of individual exposure ranges cannot be calculated without better data on actual exposure conditions, such as number of smokers, quantity of tobacco products smoked, frequency of exposure, and building ventilation.
The variability of individual exposure conditions is better addressed by probabilistic risk assessment which uses probability distributions to characterize exposure parameters.
In a study by the ADHS on economic costs and deaths attributable to smoking, infant mortality caused by mothers smoking during pregnancy was estimated at 31 deaths in Arizona in 1989. The distribution is shown in Table 3.2.
Table 3.2 Infant Mortality Caused by Mothers Smoking During Pregnancy, Arizona 1989
------------------------------------------------ | Cause of Death | Deaths | ================================================ | Low Birth Weight/Short Gestation | 8 | ------------------------------------------------ | Respiratory Distress Syndrome | 3 | ------------------------------------------------ | Respiratory Condition Newborn | 9 | ------------------------------------------------ | Sudden Infant Death Syndrome | 11 | ------------------------------------------------ | Total | 31 | ------------------------------------------------
There are two situations deserving special consideration:
o ETS exposure to the child in the perinatal period
o ETS exposure to the fetus in intero
The Arizona SIDS deaths estimated by ADHS are more representative of Arizona than are estimates extrapolated from the American Medical Association data on total U.S. SIDS deaths attributed to ETS.