Researchers in the 1930s, 1940s, and 1950s began to amass evidence of the adverse effects of secondhand smoke; In 1957, Surgeon General Leroy Burney announced that the U. S. Public Health Service took the position that there was a causal relationship between lung cancer and smoking. In 1964, Surgeon General Luther Terry published Smoking and Health: Report of the Advisory Committee of the Surgeon General of the Public Health Service, which was the first in the series now referred to as the Surgeon General's reports. It was a landmark publication that first linked smoking with numerous diseases.
Smoking is the leading cause of mortality, disability, and preventable disease in the U. S. Approximately 40 million adults and 4.7 million middle and high school students use at least one tobacco product, which includes e-cigarettes. Since 1964, there have been about 2.5 million deaths in non-smokers caused by complications from secondhand smoke. There is no safe level of exposure to secondhand smoke; even brief periods can be dangerous.
Smoking has been shown to cause "several types of cancers, including laryngopharyngeal, esophageal, gastric, hepatic, renal, cervical, and hematologic cancers." However, Kim et al. were the first researchers to perform a meta-analysis of the associations of secondhand smoking across all types of cancer. Even though research has unarguably proven that smoking causes lung cancer, 10-15% of all lung cancers occur in people who have never smoked; it is the leading cause of deaths related to cancer in non-smokers. The authors performed a literature review with six inclusion criteria: "study on the prevalence or incidence of cancer associated with secondhand smoke, primary observational study with case-control or prospective cohort design, human study, study on never-smokers, study on any type of histologically confirmed cancer, except skin cancer or carcinoma in situ, and study with clear definition of secondhand smoke or passive smoking."
The meta-analysis was performed on 40 epidemiological studies with the goal of verifying whether there was an increased risk across all types of cancer from exposure to secondhand smoke. Most secondhand smoke comes from smoke exhaled by the smoker (mainstream smoke) or from the tip of the burning cigarette (sidestream smoke),.Sidestream smoke contains 17 carcinogens including benzopyrene at 4.5 times higher and N-nitrosodimethylalanine at 00 times than mainstream smoke. The data from this study confirmed that exposure to secondhand smoke increases the risk for all types of cancer by 16%. They also found that the risk of breast cancer was increased by 24% and lung cancer by 25%.
The authors concluded that because there is a significant risk of cancer from secondhand smoke, clinicians should take a comprehensive history concerning secondhand smoke at home or work; public health policies should be created by both medical professionals and governments to minimize exposure of non-smokers to secondhand smoke.
In 1999, The Centers for Disease Control's Office on Smoking and Health (OSH) developed the National Tobacco Control Program (NTCP) to coordinate programs that provide funding and technical support to all 50 states and U. S. territories. The goal of these programs was to reduce diseases and death related to tobacco use. Exposure to secondhand smoke has decreased in the U. S. from 88% of non-smokers with detectable levels of cotinine (the by-product of the breakdown of nicotine) in 1991 to 25% in 2012. The reduction is most likely from the laws prohibiting smoking in public places as well as a decrease in the social acceptance of smoking.
