Creator:Jose Luis Calvo Martin & Jose Enrique Garcia-Mauriño Muzquiz; Credit:Getty Images/iStockphoto

Your lungs matter. Air matters. Exposures matter. Whatever is in the air that makes contact with your lung tissue matters, whether that’s SARS-CoV-2, coal dust, silica, asbestos, diesel exhaust, wood smoke, tobacco smoke, or cannabis smoke.

Lung tissue is delicately designed for the exchange of oxygen and carbon dioxide which takes place across tissue that is one cell wide, approximately 0.2 to 2.5 µm. That’s micrometers, not millimeters. One thousand micrometers in one millimeter. The dainty latticework of the lung tissue would blush the cheeks of veteran patrons of Victoria’s Secret. It is fragile and needs to be handled with care.

Lungs are the topic of the day. The entire planet is in a frenzy to protect this vital organ, because breathing is essential to life. We are worried we don’t have enough ventilators to rescue lives. Masks are being mandated to prevent us from getting to that stage. We have essentially all but shut down the global economy. At least 2 billion people on the planet are under shelter in place orders, which has even decreased the shakiness of the planet. Yet, all cannabis dispensaries are not closed for business during the Covid19 pandemic as guidance varies from state to state.

Popular perception may be that smoking cannabis is less toxic than smoking tobacco. However, according to Dr. Suzaynn Schick, research reveals  “cannabis smoke is chemically similar to cigarette smoke.”

Dr. Suzaynn Schick is an Associate Professor of Medicine at the University of California San Francisco. She studies the health effects of air pollution in human subjects, with a special focus on the chemistry and toxicity of smoke and the heart and lung disease caused by smoking and using electronic cigarettes. Her analysis of tobacco industry research showed that the primary constituent of secondhand sidestream cigarette smoke is more toxic than the smoke inhaled by smokers. She also found that the toxicity of secondhand smoke worsens as it ages, creating third hand exposure.

By Lokal_Profil, CC BY-SA 2.5,

I spoke with Dr. Schick in April of 2019 to learn about her research examining the nature of secondhand smoke generated by cannabis smoke. She is one of the first researchers studying the air pollution generated by cannabis smoke.  The chemical content of the smoke generated by smoking tobacco and cannabis is very similar, and just as toxic. This is an emerging area of concern since the legalization of recreational cannabis use in many states in the USA.

https://www.epa.gov/air-trends/particulate-matter-pm25-trends

Cannabis dispensaries with onsite consumption permits for use by vaping and dabbing can have particulate matter concentrations around 100 micrograms per cubic meter (µg/m3). In those venues where combustion is permitted, which means lighting up and smoking it, the particulate matter concentration can range from 1000 µg/m3 to even higher than what the meters can read.

For comparison, the average concentration in outside air across the USA is around 10-12 µg/m3 and has been steadily falling over the last couple decades. Levels in the most polluted cities in the world, like Delhi, Beijing, and Mexico City can range from 100 to 500 µg/m3.  The World Health Organization air quality guidelines suggest a limit of up to 10 µg/m3 of fine particulate matter for outdoor air. This is especially concerning for the people who work there and are exposed to these levels for 8-12 hours of the day, as well as for people with pre-existing heart and lung diseases. Even air filters and ventilation systems are not able to bring the particulate matter concentration to an acceptable level.

The Federal Drug Enforcement Agency has a complex protocol for conducting research related to cannabis, which makes studying the health effects of cannabis use cumbersome and nearly impossible. The potency of cannabis products is also highly variable, in contrast to the relatively standardized packaging of tobacco products. The legalization of recreational cannabis use isn’t based on solid scientific evidence that it is safe to use in that way.

Rather, evidence has been accumulating over the past couple decades of the harmful effects, particularly for young people and those with underlying psychiatric vulnerabilities. This is important to consider given that the 2013 Medical Expenditure Panel Survey (MEPS) showed that 1 out of every 6 Americans is using a psychiatric medication.  A statistical brief published by the MEPS in 2018 indicated that about 1 out every 8 children between the ages of 13–17 years had a diagnosis of Attention Deficit Hyperactivity Disorder between 2008 and 2015. The medical use of marijuana probably carries a risk-benefit ratio similar to other medications commonly prescribed and monitored by clinicians. Recreational use has a different use-risk-safety profile than medical use.

Dr. Schick also points out the cannabis industry can generate significant tax revenues for governmental entities, more so as the processes get increasingly capitalized and industrialized. Due to federal restrictions on banks supporting the industry, there has been less incentive for large corporations to participate in the cannabis market. In September of 2019, the United States House of Representatives passed the Secure And Fair Enforcement (SAFE) Banking Act which would allow banks to service cannabis companies in states where it has been legalized. At the time of the interview Dr. Schick was preparing to once again study the air pollution at the Hippie Hill 420 Festival in Golden Gate Park. However, this year the gathering has been canceled due to Covid19 shelter in place orders issued by the State of California, which are in effect until further notice.

In this interview, Dr. Schick gives a brief overview of the differences between vaping, dabbing, smoking, and edibles, and their varying pharmacodynamics, metabolism, and toxicities. She reports measuring significant levels of aldehydes and ketones in the smoke produced by smoking cannabis, similar to the levels in tobacco smoke. We don’t yet know the identity or levels of noxious gases that are emitted by dabbing or vaping marijuana.

NNK chemical structure

The studies on third hand toxicities produced by marijuana smoking are also still pending. Third hand exposure refers to the chemicals that sticks to the clothes, furniture, and walls in the rooms where smoking has occurred. The substances can react with ozone to produce a highly toxic substance. In the case of cigarette smoking, nicotine in reaction with ozone produces nicotine-derived nitrosamine ketone (NNK), a potent carcinogen. The Centers for Disease Control and Prevention reports that NNK has been found in the urine of more than a third of nonsmoking adults, with levels 2-3 times higher in children with second and third hand exposure.

From her professional scientific perspective, Dr. Schick offers a strong warning that smoking cannabis or tobacco is not safe. She says it is “magical thinking” to imagine there is no health risk from smoking marijuana. And yet, in this era, when we are prioritizing the health and safety of our community by severely restricting our personal freedoms, in order to prevent the lung failure and potential deaths of our fellow citizens, the recreational use of cannabis has been determined to be an essential service.