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Why It Matters

For decades, we have understood the serious health risks posed by secondhand tobacco smoke. Across the nation, states have enacted laws that recognize this and prohibit indoor smoking in most public places. Today, research is showing that marijuana smoke and aerosols from electronic smoking devices contain many of the same cancer-causing chemicals as tobacco smoke.

Did You Know?

  • Chemicals and other elements in secondhand marijuana smoke identified through research include hydrogen cyanide, ammonia, cadmium, formaldehyde, acetone, arsenic, benzene, toluene, nickel, chromium and lead.

  • The aerosols emitted from electronic smoking devices is not harmless to bystanders. It can contain harmful and potentially harmful substances, including nicotine, heavy metals like lead, volatile organic compounds, and cancer-causing agents, according to the Centers for Disease Control. Electronic smoking devices are also unregulated products that have no requirements for ingredient disclosure, accurate labeling, or quality control.

  • According to the Colorado Department of Public Health and Environment: "Secondhand smoke from marijuana has many of the same chemicals as smoke from tobacco, including those linked to lung cancer. While more studies are needed, secondhand smoke from marijuana may increase the risk of lung cancer. Also, secondhand smoke from marijuana can cause lung irritation and asthma attacks, and makes respiratory infections more likely. If you have children or non-users in your family or home, it is important to practice safer smoking behaviors, like not smoking indoors or in your car."

  • Marijuana smoke was added to the list of chemicals known to cause cancer and reproductive toxicity under the Safe Drinking Water and Toxic Enforcement Act (Proposition 65) in California in 2009 by the California Environmental Protection Agency. In its report on marijuana the agency identified at least 33 individual constituents present in both marijuana smoke and tobacco smoke that are Proposition 65 carcinogens.

  • One in six infants and toddlers admitted to a Colorado hospital with coughing, wheezing, and other symptoms of bronchiolitis tested positive for marijuana exposure.

  • The Centers for Disease Control finds: "Secondhand marijuana smoke contains tetrahydrocannabinol (THC), the chemical responsible for most of marijuana’s psychological effects, and many of the same toxic compounds in smoked tobacco. Therefore, breathing it could affect the health and behavior of nonsmokers, including babies and children who are exposed.

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