In 1998, Canadian snowboarder Ross Rebagliati made headlines after winning the gold medal in the men’s giant slalom event at the Winter Olympics in Nagano, Japan. Just a day after his historic victory, Rebagliati faced disqualification due to a positive test for marijuana, with his urine showing 17.8 nanograms of THC—above the then-limit of 15 nanograms.
Rebagliati claimed his positive test resulted from secondhand smoke inhaled at a party prior to the Olympics. Following a contentious appeal process, he regained his gold medal, igniting discussions about the effects of secondhand cannabis smoke. This incident not only raised questions about the potency of cannabis but also about the implications for public health, particularly in a country like Australia where cannabis use is on the rise.
Understanding Secondhand Cannabis Smoke
Beyond concerns about accidental intoxication, research has identified significant respiratory risks associated with secondhand cannabis smoke. Let’s examine these effects, compare them to secondhand tobacco smoke, and evaluate whether secondhand cannabis vapor poses any health risks, particularly for Australians.
Health Risks of Secondhand Cannabis Smoke
Research indicates that secondhand cannabis smoke can affect non-smokers in two primary ways. Firstly, individuals who inhale secondhand smoke may experience mild intoxication due to THC exposure. Secondly, cannabis smoke contains a multitude of chemicals and particulates that can be toxic to those inhaling it, whether actively smoking or not.
A study conducted by researchers at Johns Hopkins University in 2014 aimed to investigate these effects on non-smokers. The researchers placed six cannabis smokers and six non-smokers in a sealed chamber for three sessions.
- In the first session, smokers consumed joints with 5.3% THC in an unventilated environment.
- The second session involved 11.3% THC joints, also in an unventilated chamber.
- The final session allowed for ventilation while smokers again consumed 11.3% THC joints, simulating typical air-conditioning conditions.
The findings revealed that both ventilation and THC potency significantly influenced whether non-smokers tested positive for THC. In the first session, one non-smoker tested positive for THC levels near 20 nanograms/mL, while four non-smokers tested positive after the second session. In contrast, no participants in the ventilated session showed positive results, suggesting that proper ventilation effectively reduces secondhand smoke exposure.
While the researchers acknowledged that the extreme conditions of the study were unrealistic, they noted that positive drug tests among non-smokers in real-world settings would likely be rare, occurring primarily after immediate and extreme exposure to secondhand smoke.
Increases in Particulate Matter
A more recent 2022 study examined the effects of bong smoking, revealing that it can significantly increase particulate matter in the air—up to 1,000 times higher than baseline levels. Even 12 hours post-smoking, the particulate concentration remained over ten times greater than before smoking commenced. This exposure is concerning, as elevated particulate matter has been linked to decreased lung function and heightened mortality rates from lung-related diseases, including lung cancer and heart disease.
Despite these findings, no definitive causal link between secondhand cannabis smoke and specific illnesses has been established. Dr. Benjamin Caplan, a cannabis clinician and Chief Medical Officer of the CED Clinic, emphasizes the need for contextual understanding in interpreting this data. He highlights that chronic exposure to air pollution, common in urban areas of Australia, is more likely to pose a significant health risk compared to secondhand cannabis smoke.
“It is hard for anyone to convincingly argue that the dangers of cannabis smoke consumed secondhand pose greater harm than the ever-present smoke and smog of modern city life,” Dr. Caplan states. “Whether secondhand cannabis smoke represents a meaningful drop in toxicity remains a subject of ongoing debate.”
Secondhand Cannabis Smoke vs. Secondhand Tobacco Smoke
There’s a common belief that cannabis smoke is less harmful than tobacco smoke, with many Australians unaware of the potential risks. Approximately 27% of young adults in Australia perceive secondhand cannabis smoke exposure as safe. However, both types of smoke can trigger asthma attacks, respiratory infections, and lung irritation.
Interestingly, cannabis smoke has been found to produce more particulate matter than tobacco smoke. The 2022 bong-smoking study revealed that bong smoke generated four times as much particulate matter as cigarette smoke. This high level of air pollution could potentially contribute to health issues for those exposed, including the smokers themselves.
Research also suggests that while both types of smoke can be harmful, tobacco smoke is significantly more carcinogenic. Cannabis smoke has not been definitively linked to tobacco-related cancers, such as lung, colon, or rectal cancer. Some studies even suggest that the beneficial compounds in cannabis, like cannabinoids, may reduce the carcinogenic effects associated with tobacco.
Dr. Caplan points out that much of the existing research on secondhand tobacco smoke risks has been loosely applied to cannabis smoke without sufficient evidence. “In terms of chemical constituents, nicotine is a poisonous toxin, while the harmful effects associated with cannabis smoke are less clear,” he explains.
The Implications of Vaping
With the rise of vaping, it’s essential to understand its impact on secondhand exposure. Recent studies conducted in well-ventilated spaces in Australia where vaping was permitted (but smoking was banned) indicated that secondhand vapor could still pose risks to cardiovascular health. The concentration of particulates increased significantly during peak hours of use.
“While vapor may contain fewer potential irritants than smoke, it can still create a dense cloud of material,” Dr. Caplan notes. However, it’s also essential to recognize that cannabis vapor typically produces fewer toxic compounds compared to cannabis smoke, primarily due to the lower temperatures at which it is produced.
Conclusion: Navigating Cannabis Use in Australia
As Australia navigates its evolving cannabis landscape, understanding the implications of secondhand cannabis smoke is crucial. While research indicates that both cannabis and tobacco smoke can pose health risks, the ongoing debate about their comparative harms highlights the complexity of public health discussions surrounding cannabis.
For Australians considering cannabis use, whether medicinal or recreational, it’s essential to remain informed about potential risks associated with secondhand exposure, especially in communal or enclosed spaces. As more studies emerge, the public can better understand the implications of cannabis consumption and make informed decisions regarding their health and well-being.
