Secondhand Marijuana Smoke Fact Sheet 2018-04-09T14:53:03+00:00

Secondhand Marijuana Smoke

Fact Sheet

“Smoke is smoke. Both tobacco and marijuana smoke impair blood vessel function similarly. People should avoid both, and governments who are protecting people against secondhand smoke exposure should include marijuana in those rules.”
-Matthew Springer, cardiovascular researcher and Associate Professor of Medicine, University of California, San Francisco

Facts about secondhand marijuana smoke:

  • Marijuana smoke is created by burning components of plants in the genus Cannabis.
  • Secondhand marijuana smoke is a complex chemical mixture of smoke emitted from combusted marijuana and the smoke that is exhaled by the user.
  • Secondhand marijuana smoke contains fine particulate matter that can be breathed deeply into the lungs.
  • Secondhand marijuana smoke contains many of the same cancer-causing substances and toxic chemicals as secondhand tobacco smoke. Some of the known carcinogens or toxins present in marijuana smoke include: acetaldehyde, ammonia arsenic, benzene, cadmium, chromium, formaldehyde, hydrogen cyanide, isoprene, lead, mercury, nickel, and quinoline.1
  • Marijuana smoke contains tetrahydrocannabinol (THC), the active chemical in cannabis.

Health risks of exposure to secondhand marijuana smoke:

Since marijuana is illegal under federal law, there have been a limited number of studies examining health risks associated with marijuana use and exposure in the United States. Health risks from primary and secondhand smoke exposure may also be difficult to determine as marijuana is often used in combination with tobacco.

However, peer-reviewed and published studies do indicate that exposure to secondhand marijuana smoke may have health and safety risks for the general public, especially due to its similar composition to secondhand tobacco smoke.

  • Secondhand smoke from combusted marijuana contains fine particulate matter that can be breathed deeply into the lungs,2 which can cause lung irritation, asthma attacks, and makes respiratory infections more likely. Exposure to fine particulate matter can exacerbate health problems especially for people with respiratory conditions like asthma, bronchitis, or COPD.3
  • Significant amounts of mercury, cadmium, nickel, lead, hydrogen cyanide, and chromium, as well as 3 times the amount of ammonia, are found in mainstream marijuana smoke than is in tobacco smoke.4
  • In 2009, the California Office of Environmental Health Hazard Assessment added marijuana smoke to its Proposition 65 list of carcinogens and reproductive toxins, also known as the Safe Drinking Water and Toxic Enforcement Act of 1986. It reported that at least 33 individual constituents present in both marijuana smoke and tobacco smoke are Proposition 65 carcinogens.5, 6
  • Secondhand smoke from marijuana has many of the same chemicals as smoke from tobacco, including those linked to lung cancer.7
  • Secondhand marijuana exposure impairs blood vessel function. Published studies on rats show that thirty minutes of exposure to secondhand marijuana smoke at levels comparable to those found in restaurants that allow cigarette smoking led to substantial impairment of blood vessel function. Marijuana smoke exposure had a greater and longer-lasting effect on blood vessel function than exposure to secondhand tobacco smoke.8
  • Secondhand marijuana smoke and secondhand tobacco smoke is similar in many ways. More research is needed, but the current body of science shows that both tobacco and marijuana smoke have similar harmful health effects, such as atherosclerosis (partially blocked arteries), heart attack, and stroke, because of their similar chemical composition.9
  • People who are exposed to secondhand marijuana smoke can have detectable levels of THC in their blood and urine.10
  • Marijuana also can be contaminated with mold, insecticides or other chemicals that may be released in secondhand smoke.11

Including Marijuana Smoking in Smokefree Public Place and Workplace Laws:

  • Everyone has the right to breathe smokefree air. Smokefree policies are designed to protect the public and all workers from exposure to the health hazards caused by exposure to secondhand tobacco smoke. The same should be true for secondhand marijuana smoke.
  • The percent of U.S. adults who use marijuana more than doubled from 4.1% to 9.5% between 2001-2002 and 2012-2013,12 which may also indicate an increase in exposure to secondhand marijuana smoke.
  • The American Society for Heating, Refrigeration, and Air Conditioning Engineering (ASHRAE) is the organization that develops engineering standards for building ventilation systems. ASHRAE now bases its ventilation standard for acceptable indoor air quality on an environment that is completely free from secondhand tobacco smoke, secondhand marijuana smoke, and emissions from electronic smoking devices.13
  • In order to protect public health, improve consistency, and aid enforcement, smokefree laws for public places and workplaces should include tobacco as well as marijuana, whether it is smoked or aerosolized. Allowing marijuana smoking in places where smoking is now prohibited could undermine laws that protect the public from exposure to secondhand smoke. The Tobacco Control Legal Consortium issued an informative brief on Lessons from Tobacco Control for Marijuana Regulation.14
  • Smokefree policies provide incentives to quit smoking, help denormalize smoking behavior, and are particularly effective among youth and young adults who are vulnerable to visual cues and social norms of smoking. It is likely that smokefree policies for marijuana will have a similar effect.
  • As of October 2, 2017, there are approximately 266 municipalities and 11 states that explicitly restrict marijuana use in smokefree spaces in some manner.

In the interest of public health, the use of combustible or aerosolized marijuana should be prohibited wherever tobacco smoking is prohibited.

ANR Foundation’s Position on Exposure to Secondhand Marijuana Smoke:

Marijuana smoke is a form of indoor air pollution. Therefore, ANRF includes marijuana within our definition of smoking, and all of our model laws and policies include a prohibition on smoking marijuana wherever smoking of tobacco products is not allowed. ANRF does not have a position on whether marijuana should be legalized; however ANRF is against smoking in ways that harm other people. In states where marijuana is legalized, marijuana use should be prohibited in all smokefree spaces.

Nobody should have to breathe secondhand marijuana smoke at work, in public, or where they live. If we want healthy, smokefree air for workers and the public, then products like marijuana and electronic smoking devices (which can be used to “vape” a wide range of substances, including marijuana and hash oil) must not be used in smokefree environments where others are forced to breathe the secondhand emissions.

May be reprinted with appropriate credit to the American Nonsmokers’ Rights Foundation.
Copyright 2017 American Nonsmokers’ Rights Foundation. All rights reserved.

REFERENCES

  1. Moir, D., et al., “A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two smoking machine conditions, ” Chem Res Toxicol 21: 494-502. (2008).
  2. Hillier, FC.; et al. “Concentration and particle size distribution in smoke from marijuana cigarettes with different Δ9-tetrahydrocannabinol content,” Fundamental and Applied Toxicology. Volume 4, Issue 3, Part 1, June 1984, Pages 451-454.
  3. Air and Health: Particulate Matter.” National Environmental Public Health Tracking Network, U. S. Environmental Protection Agency.
  4. Moir, D., et al., “A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two smoking machine conditions, ” Chem Res Toxicol 21: 494-502. (2008).
  5. Evidence on the Carcinogenicity of Marijuana Smoke.” Reproductive and Cancer Hazard Assessment Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency. August 2009.
  6. Wang, X., et al., “Brief exposure to marijuana secondhand smoke impairs vascular endothelial function” (conference abstract). Circulation 2014; 130: A19538.
  7. Evidence on the Carcinogenicity of Marijuana Smoke.” Reproductive and Cancer Hazard Assessment Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency. August 2009.
  8. Wang, X., et al., “Brief exposure to marijuana secondhand smoke impairs vascular endothelial function” (conference abstract). Circulation 2014; 130: A19538.
  9. Springer, M.L.; Glantz, S.A.” Marijuana Use and Heart Disease: Potential Effects of Public Exposure to Smoke,” University of California at San Francisco. April 13, 2015.
  10. Herrmann ES, et al., “Non-smoker exposure to secondhand cannabis smoke II: Effect of room ventilation on the physiological, subjective, and behavioral/cognitive effects.” Drug and Alcohol Dependence. 2015 Jun 1; 151: 194-202.
  11. Associated Press. “Marijuana may be contaminated with mold, mildew.” CBS News, December 2, 2013.
  12. Hasin DS, et al. “Prevalence of Marijuana Use Disorders in the United States Between 2001-2002 and 2012-2013.” JAMA Psychiatry. Published online October 21, 2015.
  13. ANSI/ASHRAE Standard 62.1-2013, Addenda 2015 – Ventilation for Acceptable Indoor Air Quality. Atlanta, GA: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. Atlanta, GA: American Society of Heating, Refrigerating, and Air-Conditioning Engineers.
  14. Cork, Kerry. “Toking, Smoking & Public Health: Lessons from Tobacco Control for Marijuana Regulation.” Tobacco Control Legal Consortium. June 2015.