Exposure to Second-Hand Smoke Widespread

Nearly 9 out of 10 non-smoking Americans are exposed to environmental tobacco smoke (ETS, or second-hand smoke), as measured by the levels of cotinine in their blood, according to a study conducted by the Centers for Disease Control and Prevention (CDC).

The data, reported by the CDC in this week's edition of the Journal of the American Medical Association, shows measurable levels of cotinine in the blood of 88 percent of all non-tobacco users. The presence of cotinine, a chemical the body metabolizes from nicotine, is documentation that a person has been exposed to tobacco smoke. Serum cotinine levels can be used to estimate nicotine exposure over the last 2 to 3 days.

"This study documents for the first time the widespread exposure of people in the U.S. to environmental tobacco smoke. This new information will be critical in estimating the extent of related disease and developing effective public health strategies," said David Satcher, M.D., Ph.D., director, CDC.

While this study itself did not address the health effects of environmental tobacco smoke, the 1993 report from the Environmental Protection Agency (EPA), a comprehensive analysis of many respiratory studies on the health effects of ETS, concluded that ETS caused lung cancer in adult non-smokers and serious respiratory problems in children. Based on the health hazards of ETS, EPA has classified second-hand smoke as a Group A carcinogen (known to cause cancer in humans).

Blood samples used in this study were taken from over 10,000 participants in the Third National Health and Nutrition Examination Survey (NHANES III) from 1988-1991. This survey, conducted by CDC's National Center for Health Statistics, provides nationally representative data on the health status of the U. S. population through physical examinations and medical interviews.

NHANES collected data to estimate the extent of exposure of the U.S. population to ETS and to examine the contribution of the home and workplace environment to ETS exposure. CDC's National Center for Environmental Health conducted the laboratory analysis of the serum samples and analysis of the data.

Questionaire data from NHANES III on reported exposure to ETS show that 43 percent of U.S. children aged 2 months through 11 years lived in a home with at least one smoker, and that 37 percent of adult non-tobacco users lived in a home with a smoker or reported exposure to ETS at work.

Both the number of smokers in the household and the hours exposed at work were associated with increased serum cotinine levels. Data from NHANES III also revealed that the cotinine levels, and, therefore, exposure to second hand smoke was higher among children, non-Hispanic blacks, and males.

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