Tobacco harm reduction

Background of tobacco use prevalence

Tobacco consumption is still the leading cause of preventable disease and death in the United States[1]. As reported in surveys from 2020 and 2023 by the National Center for Health Statistics, 10.9% of adults in the United States smoke cigarettes, and 7.5% of grade 12 adolescents smoke cigarettes [2]. That's almost 1 out of every 11 adults, 42.1 million people. Younger people (age 25-44) and people with lower education levels have higher smoking rates[3]. Efforts to reach these populations specifically is important to improve health outcomes. 

Tobacco harm reduction products

Harm reduction in tobacco use is a controversial topic. A main concern is in regards to unintended consequences of introducing new tobacco products onto the market, such as the surge in youth use of electronic cigarettes to almost 1 in 4 of grade 12 U.S. adolescents in 2020 [2] that were intended as a smoking cessation technique for adults from combustible tobacco products. As reported by Hatukami and Carroll (2020) about the efficacy of tobacco harm reduction strategies "The lowest harm is likely to be associated with FDA regulated medicinal nicotine products. Yet, FDA has been conservative in approving any medicines that might have appeal and compete with the addictiveness of cigarettes, resulting in modestly effective medications and stagnation of any innovative pharmacological treatments[4]." Due to the stagnation of innovative pharmacological treatments and only modest efficacy from medications currently on the market, alternative forms of harm reduction may have benefits for these populations.

Facets of tobacco addiction

Tobacco addiction is multifaceted and involves the actual chemical addiction to nicotine which quickly releases dopamine in the brain, but also involves social aspects and behavioral patterns such as always smoking during a break at work, smoking in the car or after meals. The physical movements involved with tobacco consumption such as the hand-to-mouth movement while consuming tobacco is also part of this complex issue, as well as physical sensations such as the inhalation and exhalation of smoke, the feeling of holding a cigarette, the ritual of tapping a pack of cigarettes before opening it, etc. 

Tobacco additives

When considering an alternative to combustible tobacco products, a product that mimics a cigarette but bestows fewer health risks may be worth considering. To create cigarettes, tobacco leaves and harvested, dried, and cured before being being cut and formed into cigarettes. During these processes a large number of substances are used for various reasons such making processing and manufacturing easier, improve flavor, prolong shelf life, etc.  Such ingredients sound fairly harmless, such as sugars, gums, and cellulose fiber, but when burned many of these ingredients undergo chemical reaction that form dangerous compounds such as formaldehyde and acetaldehyde. It is well known that cigarette smoke contains chemicals such as formaldehyde and acetaldehyde, although these chemicals are not added to cigarettes directly.  US-style tobacco is about 10% additives by weight "...mostly in the form of sugars, humectants, ammonia compounds, cocoa, and licorice[5]." The American tobacco industry has to report additives included in their products, with more than 100 additives out of the 599 reported as being used for tobacco production having pharmacological actions that are not well understood and could be impacting health outcomes for a variety of reasons[5].  

Heavy metals in tobacco

In addition to additives intentionally introduced into tobacco products, the tobacco plant itself bioaccumulates heavy metals such as cadmium that also poses significant health risks[5]. By comparison, Cannabis sativa accumulates the majority of heavy metals in the roots and not in the above-ground plant parts [7]. For example, when looking at cadmium, lead, and copper, there are significant differences seen in tobacco as compared to cannabis. Where in one study tobacco leaves cadmium ranged from 0.221–13.2 mg/kg, with an average of 4.89 mg/kg [8], four varieties of hemp leaves tested had 0.03-0.04 mg/kg [7]. Likewise, the same studies found average levels of lead in tobacco leaves (2.33 mg/kg) was much higher than average lead levels in cannabis leaves (0.52 mg/kg). However, average copper accumulation in tobacco leaves (4.35 mg/kg) was comparable to cannabis leaves (4.43 mg/kg)[7,8].

Other detriments of tobacco production

Tobacco also depletes soil of nutrients more than other major crops and requires heavy use of fertilizer, pesticides, and growth regulators [6]. There are other implications to consider as well, such as unfair and dangerous labor practices for workers.  

Alternative harm reduction strategy using hemp leaf cigarettes

When considering why cigarettes have such negative health outcomes, two major areas of concern are the characteristics of the tobacco plant itself in the uptake of heavy metals into the leaves, and the plethora of additives involved in manufacturing. While more research is necessary to expound on how and in what environmental conditions cannabis bioaccumulates heavy metals, it may be a viable alternative to use cannabis leaves in a combustible product. There would of course need to be prototypes of hemp leaf cigarettes that utilized different methods of preparing the product that did not involve the addition of similar, damaging additives, while still producing a palatable product.

A potential benefit to using cannabis leaves may also be realized through trials and research. While cannabinoid, terpenoid, and flavonoid content of cannabis leaves are relatively low at around 1-2%, these compounds may still offer benefits such as anti-inflammatory properties. This would have to tested after the curing process was complete to determine if any quantifiable beneficial compounds remain in the finished product.  Additionally, the finished hemp leaf product could be infused with such compounds to increase flavor or add the benefits of CBD or any number of other cannabinoids, many of which have pharmacological potential as useful drugs. Of course it would be imperative that any such additives be rigorously assessed for safety to ensure any addition compounds formed during combustion were not harmful.  

The process for curing tobacco is a long process that involves fermentation to develop flavor and reduce harshness of the tobacco when smoked. If cannabis leaves were treated in the same way, it's possible that this could offer cigarette smokers an alternative that still involves many of the behavioral aspects of cigarette smoking that are notable components of the challenges involved in smoking cessation. Put a different way, someone who no longer wants to smoke cigarettes but is not ready to stop smoking could have a 1:1 replacement for cigarettes that allows for no disruption in their daily habits and rituals and may therefore be attainable. Hemp leaf cigarettes could also be alternated with cigarettes such that they can still engage in smoke inhalation and the hand-to-mouth movement and not be excluded from social situations where smoking in common or even necessary (i.e., getting a smoke break at a job). 

A product currently on the market that bodes well for hemp leaf cigarettes as a product are hemp papers and hemp wraps. While the pulp from the stem of the plant is often used, there are products available that utilize whole hemp leaf for wraps as well. One issue with these products appears to be fragility that comes from the product being too dry. If the process could be improved to address this issue, palatability could be increased and hemp leaf cigarettes becoming a valuable product would be more feasible. 

Hemp flower cigarettes

Hemp flower cigarettes are a product that is already on the market, but there are several issues with such products. Firstly, these products may not be cured appropriately and this seems to lead to a harsh, unpleasant smoke. Secondly, skillfully grown and well cured hemp flower is indistinguishable from marijuana in appearance and smell and this could cause problems in terms of certain professions who may benefit from such a substitution but for whom the smell of cannabis could be problematic (security guards, nurses, police, etc.). Likewise, an individual who is trying to cease or reduce marijuana consumption may also find this comparison unhelpful for their purposes. 

Hemp flower cigarettes in which the flower is high quality, seedless, and properly cured could also be a great substitution for individuals who have no concerns about aroma. However, even in this situation there are drawbacks to producing a product using hemp flower. Firstly, cultivating hemp flower requires state compliance with THC testing requirements (<0.3% by dry weight), and current cultivars of hemp available for commercial production are often inadequate because they frequently surpass 0.3% THC by weight and therefore the entirety of the crop has to be destroyed. Cultivar trials across different regions of the world are necessary to deem how cultivars perform and which are reliable under 0.3%.  

Secondly, cannabis pollen is ubiquitous in many areas, which causes the plants to be pollinated and seeds to form in the hemp. Seed production reduces metabolic resources available to produce scent and flavor compounds such as terpenoids and terpenes while also reducing yield of marketable biomass significantly because seeds can't be smoked, meaning there is less flower produced and the flower is generally not of high quality in terms of flavor. This can be mitigated by farmers cultivating triploid hemp varieties that are sterile and do not produce seeds regardless of the presence of pollen. Of course the issue of THC potency raising above 0.3% is still present with triploid cultivars, and cultivar trials are still needed to determine the suitability of a particular triploid cultivar for a specific environment. If a protocol was developed that successfully allowed for the production of cannabis leaves without the cannabis plants having to flower, this negates the necessity for state testing as only flowering hemp plants have this testing requirement. Furthermore, the time it takes to produce cannabis leaves in much shorter as compared to producing a mature cannabis inflorescence. 

In summary, cannabis leaf cigarettes may be a viable, less harmful alternative to tobacco leaf cigarettes if the quality of the product is desirable. This product could also be a viable alternative to hemp flower cigarettes as well, which have a number of challenges associated with cultivation regulations and with production of a desirable product.

References

[1] Sealock, T., Sharma, S. Smoking Cessation. StatPearls Publishing (2024). PMID: 29494049. https://pubmed.ncbi.nlm.nih.gov/29494049/

[2] Cigarette Smoking and Electronic Cigarette Use.  Early Release of Selected Estimates Based on Data From the 2023 National Health Interview Survey. https://www.cdc.gov/nchs/fastats/smoking.htm

[3] Garrett, B., et al. Socioeconomic Differences in Cigarette Smoking Among Sociodemographic Groups. https://www.cdc.gov/pcd/issues/2019/18_0553.htm#table2_down (2019). http://dx.doi.org/10.5888/pcd16.180553.  

[4] Hatukami, D., Carroll, D. Tobacco harm reduction: Past history, current controversies and a proposed approach for the future. Prev Med 140, 106099 (2020). 10.1016/j.ypmed.2020.106099. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581601/

[5] Rabinoff, M., et al. Pharmacological and chemical effects of cigarette additives. Am J Public Health 97(11), 1981-1991 (2007). 

[6] Lecours, N., Almeida, G., Abdallah J., Novotny, E. Environmental health impacts of tobacco farming: a review of the literature. Tob Control. 2012. March;21(2):191–6. 10.1136/tobaccocontrol-2011-050318

[7] Ćaćić, M., et al. Evaluation of heavy metals accumulation potential of hemp (Cannabis sativa L.). Journal of Central European Agriculture 20(2):700-711 (2019). doi:10.5513/JCEA01/20.2.2201

[8] Xi W, Ping Y, Cai H, Tan Q, Liu C, Shen J, Zhang Y. Effects of Soil Properties on Pb, Cd, and Cu Contents in Tobacco Leaves of Longyan, China, and Their Prediction Models. Int J Anal Chem. 2023 Dec 28;2023:9216995. doi: 10.1155/2023/9216995. PMID: 38178991; PMCID: PMC10766475.