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EPA Designates Passive Smoking a "Class A" or Known Human Carcinogen

[EPA press release - January 7, 1993]

EPA Administrator William K. Reilly today announced the final conclusions of EPA's assessment on the respiratory health effects of passive smoking. The assessment concludes that Environmental Tobacco Smoke (ETS), also known as secondhand smoke, is a human lung carcinogen, responsible for approximately 3,000 lung cancer deaths annually among U.S. non-smokers. It also concludes that passive smoking results in serious respiratory problems for infants and young children.

Announcing the release of the study today in a joint Washington press conference with Dr. Louis Sullivan, Secretary of the U.S. Department of Health and Human Services, Reilly said, "Today's risk assessment adds new peer-reviewed evidence to the growing scientific consensus that smoking is not just a health danger for smokers, but a significant risk for non-smokers, particularly children who are exposed to secondhand smoke. This report will be an invaluable scientific tool for policymakers and health professionals who are wrestling with the problem of exposure to passive smoke. EPA will work closely with the Department of Health and Human Services and other organizations to ensure that officials around the world are made aware of the findings of this important study."

Tobacco smoke has long been recognized as a major cause of death and disease, especially lung cancer and chronic respiratory disease in smokers. In recent years there has been concern that non-smokers may also be at increased risk as a result of their exposure to the smoke exhaled by smokers and given off by the burning end of cigarettes, pipes or cigars. This smoke contains more than 4,000 substances, at least 43 of which cause cancer in humans or animals and many of which are strong eye or respiratory irritants.

The lung cancer findings in EPA's assessment are based on several important analytical findings: first, the chemical and physical similarity of ETS to that inhaled by smokers; second, the known lung carcinogencity of tobacco smoke to smokers; third, the known exposure to ETS and uptake by the human body; and fourth, a thorough and comprehensive review of more than 30 studies in both the United States and abroad that examined the relationship between lung cancer and exposure to secondhand smoke in people who never smoked, usually the spouses of smokers. EPA concluded from the total "weight of evidence" of all the studies that ETS increases the risk of lung cancer in non-smokers.

The report also cites some of the specific effects of passive smoking on children. The report's conclusions on childhood respiratory health are based on more than 100 studies in children documenting the fact that secondhand smoke is a problem for young children and infants. Some of the effects cited:

  • ETS exposure causes additional episodes and increased severity of symptoms in asthmatic children. The report estimates that 200,000 to 1 million asthmatics have their condition worsened by exposure to ETS.
  • ETS exposure is a risk factor for new cases of asthma in children who have not previously displayed symptoms.
  • ETS exposure causes an increased risk of lower respiratory tract infections such as bronchitis and pneumonia in infants and young children. The report estimates that exposure to parents' secondhand smoke will lead to 150,000 to 300,000 cases annually in children up to 18 months old.
  • ETS exposure causes an increased prevalence of fluid in the middle ear, symptoms of upper respiratory tract irritation and a small yet significant reduction in lung function.

Following a second review in the summer of 1992, EPA's Science Advisory Board (SAB), fully endorsed the risk assessment, including the conclusions that ETS should be classified as a known human carcinogen (officially called an EPA Group A carcinogen, the Agency's category of greatest scientific certainty for known or suspected carcinogens). The SAB also endorsed the risk estimate that between 2,500 and 3,300 lung cancer deaths per year among U.S. non-smokers are attributable to ETS exposure, as well as the findings on other respiratory effects. The SAB suggested relatively minor revisions in its November 1992 letter to the Agency. Those revisions have been made. The SAB is EPA's independent panel of outside scientific advisors that routinely reviews draft EPA reports.

EPA also received and reviewed more than 100 comments from the public and integrated appropriate ones into the final risk assessment.

EPA has no authority to regulate any type of smoking, nor is EPA's report binding on the policy or regulatory program of any other federal, state or local government agency or any private organization. In cooperation with other government agencies, EPA will carry out an education and outreach program over the next two years to inform the public and policymakers about what they can do to reduce the health risks of ETS as well as other indoor air pollutants.

This 530-page report, which has been in development since 1988, has been through extensive review and revisions. It was prepared under authority of Title IV of Superfund (The Radon Gas and Indoor Air Quality Research Act of 1986), which directs EPA to conduct a research and information dissemination program on all aspects of indoor air quality.

Today's final report, prepared by the Office of Health and Environmental Assessment in EPA's Office of Research and Development, with major support from the Indoor Air Division of EPA's Office of Air and Radiation, was released in draft to the general public for review and comment in June 1990 and subsequently reviewed by EPA's SAB in December 1990.


Read the final report: "Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders" (EPA 600/6/90/006F) (December 1992) (PDF) (525 pp, 3.9 MB, About PDF)