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Exposure to Tobacco Smoke and Harmful Substances in Tobacco

Biomonitoring also has been the driving force for assessing people's exposure to environmental tobacco smoke (ETS), which has been identified as causing cancer in people. Children are at particular risk for harm from ETS, which may aggravate asthma in children who have the disease and greatly increase the risk for bronchitis and pneumonia among young children.

The best way to measure individual exposure to ETS is to measure levels of a chemical called cotinine. This chemical is a metabolite of nicotine and is regarded as the best biological marker for tobacco smoke exposure for both smokers and nonsmokers exposed to ETS. People with higher cotinine levels have had more exposure to tobacco smoke than people with lower levels.

When CDC developed a method for measuring very low levels of cotinine in the U.S. population, it found that 88% of the population was exposed. Data were unavailable to document that people who thought they were exposed to ETS in the workplace actually had such exposure. CDC's study showed that people who reported more exposure to ETS in the workplace had measurably higher levels of cotinine, indicating higher actual exposure. These unique data provided important justification for establishing regulations restricting smoking in public buildings.

CDC has continued to measure the population's exposure to secondhand smoke and has found that since the 1990s secondhand smoke exposure has dropped dramatically in all segments of the population. The 2006 Surgeon General's Report (The Health Consequences of Involuntary Exposure to Tobacco Smoke) used these data to highlight the public health success in reducing nonsmokers' exposure to secondhand smoke in public places.

CDC's Environmental Health Laboratory also analyzes tobacco products and cigarette smoke for the presence of harmful substances and for substances that may influence the delivery of harmful substances to the body. For instance, the laboratory not only investigates the concentration of nicotine in cigarettes and smoke but also the factors or chemicals that influence the delivery of nicotine to people. In addition to nicotine, these harmful substances include nitrosamines; tar; pesticides; carbon monoxide; volatile organic compounds (benzene, for example); metals (such as cadmium and radioactive polonium); carbonyl compounds; and polycyclic aromatic hydrocarbons.