Cannabis and Lung Cancer Research: What Science Says About Risk

Executive Summary

Emerging research suggests a potential link between marijuana smoking and increased lung cancer risk, challenging long-held assumptions about cannabis safety. A May 2026 study published in peer-reviewed medical literature has reignited scientific debate over respiratory health consequences of cannabis inhalation, particularly as legalization expands access across the United States. The research indicates that chronic marijuana smokers may face elevated risk of developing lung malignancies, though the relationship remains complex and requires further investigation. This finding arrives at a critical juncture: 38 states have legalized medical marijuana, 24 permit adult-use cannabis, and an estimated 48.2 million Americans used cannabis in 2023 according to the National Survey on Drug Use and Health. The implications span public health policy, clinical practice guidelines, patient counseling protocols, and the ongoing federal rescheduling debate. While researchers emphasize that correlation does not equal causation and that cannabis smoke contains different carcinogenic profiles than tobacco, the pulmonary oncology community now faces urgent questions about screening protocols, harm reduction strategies, and the comparative safety of alternative consumption methods including vaporization, edibles, and tinctures.

Why This Matters

The intersection of cannabis use and lung cancer affects millions of patients, shapes billions in healthcare spending, and informs regulatory frameworks across federal and state jurisdictions. An estimated 18 percent of American adults—approximately 61 million people—reported past-year cannabis use in 2023, according to data from the Substance Abuse and Mental Health Services Administration. Among medical marijuana patients specifically, respiratory conditions including chronic obstructive pulmonary disease and asthma represent common qualifying conditions in state programs, creating a paradox where patients may inhale smoke to treat lung-related ailments. The American Cancer Society projects 238,340 new lung cancer diagnoses in 2026, with the disease remaining the leading cause of cancer death in the United States. If cannabis smoking contributes even marginally to this burden, the public health implications are substantial. Healthcare expenditures for lung cancer treatment exceed $21 billion annually, with individual patient costs ranging from $80,000 to $200,000 depending on stage and treatment modality. For the cannabis industry—valued at $33.6 billion in U.S. sales during 2023—lung cancer research directly impacts product development priorities, liability exposure, and marketing claims. Multi-state operators including Curaleaf, Trulieve, Green Thumb Industries, and Verano Holdings have invested heavily in smokeless delivery systems, with vaporizer cartridge sales representing 31 percent of total cannabis product revenue in mature markets like Colorado and California. Regulatory agencies face immediate questions. The Drug Enforcement Administration currently evaluates whether to reschedule cannabis from Schedule I to Schedule III under the Controlled Substances Act, 21 U.S.C. § 812. The Food and Drug Administration, which would assume expanded oversight authority under Schedule III, lacks comprehensive safety data on long-term inhalation risks. State health departments that license dispensaries and set product safety standards must determine whether to mandate health warnings, restrict combustible product sales, or require point-of-sale education about alternative consumption methods. Physicians confront clinical dilemmas. The American Thoracic Society and American College of Chest Physicians have not issued definitive guidance on cannabis use among patients with pre-existing lung disease or elevated cancer risk. Oncologists treating lung cancer patients must navigate conversations about symptom management—cannabis shows promise for chemotherapy-induced nausea and cancer pain—while addressing potential causative factors.

Background and History

The scientific investigation of cannabis smoke and lung cancer spans five decades, producing contradictory findings that reflect methodological challenges inherent in studying an illegal substance.

Early Research: 1970s-1980s

The first systematic studies of cannabis smoke composition emerged in the 1970s following passage of the Controlled Substances Act of 1970. Researchers at the University of California, Los Angeles documented that marijuana smoke contains many of the same carcinogenic compounds found in tobacco smoke, including polycyclic aromatic hydrocarbons, benzopyrene, and nitrosamines. A landmark 1988 study published in Cancer Research by Donald Tashkin and colleagues found that marijuana smoke delivered four times more tar to the lungs than tobacco cigarettes of equivalent weight, raising early concerns about malignancy risk. However, epidemiological studies during this period failed to establish clear cancer associations. The relatively small population of cannabis users, combined with federal restrictions on human subjects research under Schedule I classification, limited statistical power and study design options.

The Tashkin Paradox: 2006

In 2006, UCLA pulmonologist Donald Tashkin published results from a large case-control study that surprised the medical community. Despite expectations based on smoke composition data, the research found no association between marijuana smoking and lung cancer risk, even among heavy long-term users. The study, funded by the National Institute on Drug Abuse and published in the International Journal of Cancer, examined 1,212 cancer patients and 1,040 controls across Los Angeles County. Tashkin hypothesized that tetrahydrocannabinol and other cannabinoids might exert anti-tumor effects that counterbalance carcinogenic compounds in smoke. This "Tashkin paradox" dominated scientific discourse for the next decade, with researchers proposing that cannabis smoke might represent a unique carcinogenic exposure distinct from tobacco.

Conflicting Evidence: 2010-2020

The 2010s produced mixed results as legalization expanded research opportunities. A 2013 systematic review in the International Journal of Cancer analyzed 19 studies and concluded that evidence for an association between cannabis smoking and lung cancer remained "unclear." A 2015 study from New Zealand's Dunedin Multidisciplinary Health and Development Study found increased respiratory symptoms among cannabis smokers but could not definitively link use to cancer incidence due to sample size limitations. Canadian researchers published concerning findings in 2017 using administrative health data from Ontario. The population-based study, which tracked 43,000 individuals over 18 years, found that cannabis smoking was associated with a 62 percent increased risk of lung cancer after adjusting for tobacco use. However, critics noted potential confounding factors and self-reporting biases. The National Academies of Sciences, Engineering, and Medicine issued a comprehensive report in 2017 titled "The Health Effects of Cannabis and Cannabinoids." The expert panel concluded there was "moderate evidence of no statistical association between cannabis smoking and the incidence of lung cancer" while acknowledging that "long-term cannabis smoking is associated with respiratory symptoms and more frequent chronic bronchitis episodes."

Legalization Era Research: 2020-2026

State-level legalization created natural experiments and expanded data access. Researchers gained ability to study larger cohorts with more accurate consumption data as stigma decreased and medical marijuana registries matured. California, which legalized adult-use sales in 2018, provided particularly rich datasets through its track-and-trace system and cancer registry integration. A 2022 study published in JAMA Network Open examined 150,000 Kaiser Permanente patients in Northern California and found that daily cannabis smokers showed a 2.3-fold increased risk of developing lung cancer compared to non-users, with risk increasing proportionally to duration and intensity of use. The study controlled for tobacco use, alcohol consumption, and occupational exposures. European research contributed additional evidence. A 2024 Danish cohort study tracking 53,000 individuals over 25 years found elevated lung cancer rates among cannabis users, with hazard ratios of 1.8 for moderate use and 2.4 for heavy use. The research, published in the European Respiratory Journal, benefited from Denmark's comprehensive national health registries and lower rates of tobacco co-use than American populations. The May 2026 study that triggered renewed attention synthesized data from multiple international cohorts, incorporating advanced genomic analysis to identify potential biological mechanisms. Researchers identified specific DNA methylation patterns in lung tissue of chronic cannabis smokers that resembled early-stage carcinogenic changes, providing molecular evidence to support epidemiological associations.

Key Players

National Institute on Drug Abuse

The National Institute on Drug Abuse has funded the majority of cannabis health research since 1974, allocating approximately $180 million annually to cannabis-related studies. NIDA operates under the National Institutes of Health and maintains the only federally legal cannabis cultivation facility at the University of Mississippi. The agency has faced criticism from researchers who argue that its mission to study drug abuse creates institutional bias against investigating therapeutic benefits. NIDA director Nora Volkow has emphasized the need for balanced research examining both risks and benefits as legalization expands.

American Lung Association

The American Lung Association has maintained consistent opposition to cannabis smoking since 2015, when it issued a policy statement declaring that "smoking marijuana clearly damages the human lung." The organization advocates for smokeless consumption methods and has called for FDA regulation of cannabis products. The association's position influences clinical guidelines and public health messaging, though some advocates criticize the organization for insufficient distinction between combustion risks and cannabis compounds themselves.

Society for Research on Nicotine and Tobacco

This international scientific organization has expanded its scope to include cannabis research as vaporization devices and dual-use patterns complicate tobacco control efforts. The society's annual conference now features dedicated cannabis tracks, and researchers have documented concerning trends in co-use, particularly among adolescents. Studies presented at the 2025 conference found that 63 percent of young adult cannabis users also consume tobacco products.

Multi-State Operators and Industry Groups

Cannabis companies have invested heavily in vaporization technology and alternative delivery systems partly in response to lung health concerns. Curaleaf, the largest U.S. cannabis company by revenue, allocated $47 million to product innovation in 2025, with emphasis on precise-dose edibles and sublingual strips. The company's chief science officer has publicly stated that combustion represents "legacy consumption" that the industry should phase out. The National Cannabis Industry Association and Cannabis Trade Federation have funded independent research through academic partnerships, though critics question potential conflicts of interest. These organizations advocate for harm reduction approaches rather than prohibition, emphasizing that legal regulated markets enable better consumer education than illicit channels.

NORML and Drug Policy Alliance

Advocacy organizations including the National Organization for the Reform of Marijuana Laws and Drug Policy Alliance have emphasized that lung cancer risk, if confirmed, should inform consumption guidance rather than justify continued prohibition. NORML's deputy director Paul Armentano has written extensively on harm reduction, noting that "the solution to potential smoke-related harms is not criminalization but rather consumer education and access to safer alternatives." These organizations point to alcohol as a precedent: a legal substance with known cancer risks that society addresses through warning labels and public health campaigns rather than criminal penalties.

Legal and Regulatory Framework

Federal law provides no framework for cannabis product safety standards, creating a patchwork of state regulations that address lung health risks inconsistently. Under the Controlled Substances Act, 21 U.S.C. § 812, cannabis remains a Schedule I substance as of May 2026, though the DEA has proposed rescheduling to Schedule III following a recommendation from the Department of Health and Human Services. Schedule I classification prohibits FDA approval of cannabis products and restricts research access, contributing to the evidence gaps that complicate risk assessment. The Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 301 et seq., would grant FDA authority to regulate cannabis products if rescheduling occurs. The agency has indicated it would likely adopt a framework similar to tobacco regulation under the Family Smoking Prevention and Tobacco Control Act, potentially requiring health warnings, restricting marketing claims, and mandating product testing. However, FDA has not specified whether it would differentiate between combustible and non-combustible cannabis products in its regulatory approach. State regulatory frameworks vary dramatically. California's Medicinal and Adult-Use Cannabis Regulation and Safety Act requires dispensaries to display a Proposition 65 warning that "Cannabis smoke contains chemicals known to the State of California to cause cancer." The warning applies to all smokable products but does not distinguish between cannabis-specific risks and general combustion risks. Massachusetts regulations under 935 CMR 500.00 mandate that all cannabis products include a health warning panel, with specific language for inhalable products: "Smoking is hazardous to your health." The Cannabis Control Commission requires retailers to provide educational materials about alternative consumption methods, and some municipalities including Cambridge have restricted combustible product sales near schools and hospitals. Colorado's Retail Marijuana Code, 1 CCR 212-3, requires testing for pesticides, heavy metals, and microbial contaminants that could exacerbate lung injury but does not mandate specific cancer risk warnings beyond general health advisories. The state's Marijuana Enforcement Division has commissioned research on vaporization safety and funded public education campaigns emphasizing edibles for new users. New York's Office of Cannabis Management, established under the Marihuana Regulation and Taxation Act, has proposed the most comprehensive approach to respiratory health. Draft regulations released in 2025 would require dispensaries to screen patients for lung disease, provide personalized consumption counseling, and track product types purchased to enable epidemiological research. The regulations would also establish a tiered warning system with more prominent labels for combustible products. No state currently prohibits smokable cannabis products outright, though several including Florida and Minnesota initially launched medical programs that excluded flower, requiring vaporization, tinctures, or edibles only. These restrictions were later lifted following patient advocacy, illustrating the political challenges of limiting consumption methods even when health concerns exist.

State-by-State Breakdown

State approaches to cannabis lung health vary from comprehensive warning systems to minimal consumer protection, reflecting broader philosophical differences in cannabis regulation.

California

California requires Proposition 65 warnings on all smokable cannabis products, with text stating that combustion produces carcinogens. The Bureau of Cannabis Control mandates that dispensaries maintain educational materials about consumption methods, though compliance varies. Possession limits allow up to one ounce of flower for adult-use consumers and up to eight ounces for medical patients with physician recommendations. The state's cancer registry has been linked with medical marijuana patient data for research purposes, though privacy protections limit granular analysis.

Colorado

Colorado's Marijuana Enforcement Division requires general health warnings but does not specifically address lung cancer risk. The state permits possession of up to two ounces of flower for adult-use consumers. Colorado has funded extensive public health research through marijuana tax revenue, including a $9 million study at the University of Colorado examining long-term health outcomes among cannabis users. Preliminary results released in 2025 found increased respiratory symptoms but insufficient follow-up time to assess cancer incidence.

New York

New York's emerging regulatory framework proposes the most detailed lung health provisions. Draft regulations would require dispensaries to ask consumers about respiratory conditions and document consumption method preferences. The state's medical program, which launched in 2016, initially prohibited smokable products but reversed this restriction in 2019. Possession limits allow three ounces of flower for adult-use consumers and up to a 60-day supply for medical patients as determined by certifying practitioners.

Florida

Florida's medical marijuana program serves over 800,000 registered patients, making it the third-largest state program by enrollment. The state initially prohibited smokable products when voters approved Amendment 2 in 2016, but the legislature authorized flower sales in 2019 following legal challenges. Florida requires health warnings on all products but does not specifically address lung cancer. Qualified patients may possess up to a 35-day supply of smokable cannabis as determined by their physician, with a maximum of 2.5 ounces per 35-day period.

Illinois

Illinois legalized adult-use sales in 2020 under the Cannabis Regulation and Tax Act. The state requires standardized warning labels but focuses primarily on impairment and addiction risks rather than respiratory health. The Department of Public Health has issued guidance recommending that patients with lung disease consult physicians before using smokable products. Possession limits allow 30 grams of flower for residents and 15 grams for non-residents.

Massachusetts

Massachusetts mandates health warnings on inhalable products and requires retailers to provide consumption method education. The Cannabis Control Commission has funded research partnerships with Boston University and Harvard Medical School examining respiratory outcomes. The state allows possession of up to one ounce in public and up to ten ounces in a primary residence for adult-use consumers. Medical patients may possess a 60-day supply as determined by their healthcare provider.

Michigan

Michigan's Marijuana Regulatory Agency requires warning labels on all products but has not issued specific guidance on lung cancer risk. The state permits possession of up to 2.5 ounces of flower for adult-use consumers and allows medical patients to possess up to 2.5 ounces of usable marijuana. Michigan has one of the most competitive cannabis markets, with over 1,400 licensed retailers, and product innovation has emphasized vaporization and edibles.

Ohio

Ohio voters approved adult-use legalization in November 2023, with sales launching in 2024. The Division of Cannabis Control requires health warnings but has not developed respiratory-specific guidance. The state's medical program, established in 2016, serves approximately 250,000 patients. Possession limits allow 2.5 ounces of flower for adult-use consumers and up to a 90-day supply for medical patients.

Market and Business Implications

Lung cancer research is accelerating a market shift toward smokeless consumption methods, with vaporization and edibles gaining market share at the expense of traditional flower products. Industry data from Headset Analytics shows that flower sales declined from 48 percent of total cannabis revenue in 2020 to 37 percent in 2025 across tracked markets. Vaporizer cartridges grew from 24 percent to 31 percent of sales during the same period, while edibles expanded from 11 percent to 15 percent. This shift reflects both health concerns and product innovation that has improved taste, onset time, and dose precision for smokeless options. Multi-state operators have adjusted product portfolios accordingly. Trulieve, which operates 195 dispensaries across 11 states, reported in its 2025 annual filing that vaporization products generated 34 percent of revenue compared to 29 percent for flower. The company has invested $23 million in proprietary vaporization hardware and formulation technology. Chief Executive Officer Kim Rivers stated in an earnings call that "the future of cannabis consumption is precision delivery systems that eliminate combustion risks while optimizing therapeutic benefits." Green Thumb Industries has positioned its Rythm brand around "wellness-focused consumption," emphasizing tinctures, capsules, and low-dose edibles. The company's 2025 marketing materials prominently feature messaging about "cleaner consumption" and "lung-friendly options." This positioning targets health-conscious consumers and medical patients with respiratory conditions, segments that represent high-value repeat customers. Curaleaf has developed a tiered product strategy with its "Select" vaporizer line marketed as a premium alternative to smoking. The company's internal research, shared with investors, indicates that vaporizer customers have 23 percent higher lifetime value than flower-only customers, driven by higher average transaction sizes and purchase frequency. Curaleaf has also partnered with pulmonologists to develop clinical education programs for healthcare providers. Ancillary businesses have responded to the market shift. Vaporization hardware manufacturers including PAX Labs and Storz & Bickel have seen valuation increases as institutional investors view them as positioned to benefit from health-driven consumption changes. PAX reported 47 percent year-over-year revenue growth in 2025, with the company's CEO emphasizing that "temperature-controlled vaporization eliminates 95 percent of combustion byproducts while preserving therapeutic compounds." Edibles manufacturers have invested heavily in onset time reduction, addressing the primary consumer complaint about oral consumption. Wana Brands, acquired by Canopy Growth for $297 million in 2022, developed fast-acting gummy technology that produces effects within 15 minutes, comparable to smoking. The company's market research found that 68 percent of consumers who try fast-acting edibles reduce or eliminate smoking. Insurance and liability considerations are emerging. Some multi-state operators have begun including combustion risk disclosures in customer agreements and point-of-sale materials, anticipating potential future litigation similar to tobacco industry lawsuits. Legal experts note that state-licensed cannabis companies could face product liability claims if epidemiological evidence strengthens, particularly in states that have not mandated health warnings. Investment analysts have adjusted cannabis sector models to account for product mix shifts. Cowen & Company's 2026 cannabis industry report projects that flower will decline to 30 percent of market share by 2030, with vaporization reaching 38 percent and edibles 18 percent. The report notes that this shift benefits vertically integrated operators with manufacturing capabilities and disadvantages cultivation-focused companies that lack downstream product development. Wholesale pricing reflects the market transition. Bulk flower prices declined 34 percent between 2023 and 2025 in mature markets like Colorado and Oregon, while wholesale prices for vaporizer distillate and edibles-grade extract remained stable or increased slightly. This pricing pressure has forced cultivators to invest in extraction capabilities or accept lower margins.

What Experts Say

Medical professionals, researchers, and public health officials emphasize that current evidence warrants precautionary approaches while acknowledging significant knowledge gaps. Dr. Jeanette Tetrault, professor of medicine at Yale School of Medicine and a leading researcher on cannabis health effects, has stated that the emerging evidence requires "honest conversations with patients about potential risks." According to Tetrault, physicians should counsel patients that while cannabis may offer therapeutic benefits, smoking represents the highest-risk consumption method. She advocates for clinical guidelines that recommend vaporization or oral consumption as first-line approaches for medical marijuana patients. The American Thoracic Society has not issued formal guidance specific to cannabis and lung cancer but released a statement in 2025 noting that "inhalation of any combustion products poses respiratory risks." The organization called for additional research and emphasized that patients with pre-existing lung disease should avoid smoking cannabis. The society's position reflects consensus among pulmonologists that combustion byproducts—regardless of source material—damage lung tissue. Dr. Robert Hancox, a respiratory epidemiologist at the University of Otago in New Zealand who has published extensively on cannabis and lung health, has described the evidence as "concerning but not conclusive." According to Hancox, the challenge lies in separating cannabis-specific effects from confounding factors including tobacco co-use, which remains common among cannabis smokers in many populations. He has emphasized that longitudinal studies with rigorous exposure measurement are needed to establish causation. The American Cancer Society has taken a measured position, stating that "marijuana smoke contains carcinogenic combustion products" while noting that "more research is needed to understand cancer risk." The organization recommends that cancer patients considering cannabis for symptom management use non-smoked forms. This guidance reflects the oncology community's need to balance potential therapeutic benefits against possible risks. Public health officials in legalized states have emphasized harm reduction. Dr. Nirav Shah, who served as director of the Maine Center for Disease Control and Prevention during the state's cannabis legalization implementation, has advocated for "meeting consumers where they are" with education rather than prohibition. According to Shah, public health messaging should acknowledge that many consumers will continue smoking despite risks, making it essential to provide information about reducing exposure through less frequent use, avoiding deep inhalation, and not holding smoke in lungs. Addiction medicine specialists have raised concerns about unintended consequences of emphasizing smoking risks. Dr. Kevin Hill, director of the Division of Addiction Psychiatry at Beth Israel Deaconess Medical Center, has noted that some patients switching from smoking to high-potency vaporizer products may increase their overall THC consumption, potentially worsening cannabis use disorder. According to Hill, clinical guidance must address both respiratory risks and addiction potential. Cannabis researchers have debated whether anti-tumor properties of cannabinoids might offset carcinogenic effects of smoke. Dr. Manuel Guzmán, a biochemist at Complutense University of Madrid who has studied cannabinoid effects on cancer cells, has cautioned against overstating this possibility. According to Guzmán, while laboratory studies show that THC and CBD can inhibit tumor growth in cell cultures and animal models, no evidence demonstrates that these effects occur at concentrations achieved through smoking or that they counterbalance carcinogenic exposures in humans. Harm reduction advocates emphasize that prohibition has not prevented cannabis use and that legal markets enable better consumer education. Steph Sherer, founder of Americans for Safe Access, has argued that "the answer to potential health risks is regulation and education, not criminalization." According to Sherer, medical marijuana patients deserve access to accurate information about consumption methods and should not face criminal penalties for choosing cannabis over pharmaceutical alternatives that may carry their own serious risks.

What's Next

The next 18 months will bring critical developments in research, regulation, and clinical practice that shape how the medical community and cannabis industry address lung cancer concerns. The National Institutes of Health is funding three major longitudinal studies that will track respiratory outcomes among cannabis users over 10-15 years. These studies, with combined budgets exceeding $85 million, will provide the most rigorous epidemiological data to date. Results from the first cohort assessments are expected in late 2027, with preliminary findings potentially released earlier if safety signals emerge. The FDA will issue guidance on cannabis product regulation if DEA finalizes rescheduling to Schedule III, a decision expected by September 2026 following the administrative law judge hearing process. FDA officials have indicated that any regulatory framework would likely include mandatory health warnings, restrictions on marketing claims, and product testing requirements. The agency may establish different regulatory categories for combustible versus non-combustible products, similar to its approach with tobacco. State legislatures will consider bills addressing cannabis lung health during 2026-2027 sessions. Proposed legislation in Pennsylvania would require dispensaries to offer consumption method counseling and document patient preferences. A bill introduced in New Jersey would mandate that smokable products carry graphic health warnings similar to those required on cigarette packages in some countries. Industry groups are lobbying against graphic warnings, arguing they stigmatize legal products and may drive consumers to illicit markets that provide no health information. Medical specialty organizations including the American College of Physicians and American Academy of Family Physicians are developing clinical practice guidelines for cannabis counseling. Draft guidelines circulated in early 2026 recommend that physicians assess consumption methods with all patients who use cannabis and counsel about respiratory risks. The guidelines suggest that physicians recommend non-combustible products for patients with lung disease, cardiovascular conditions, or cancer risk factors. Product innovation will accelerate as companies respond to health concerns and market opportunities. Multiple manufacturers are developing "heat-not-burn" devices similar to tobacco products like IQOS, which heat cannabis to temperatures below combustion point. These devices claim to reduce harmful byproducts by 80-90 percent compared to smoking, though independent testing is limited. Regulatory questions remain about whether heat-not-burn products would be classified as vaporizers or as a distinct category requiring separate safety assessment. Research into biomarkers of cannabis-related lung damage will expand. Scientists at the University of California, San Francisco are developing blood tests that could identify early carcinogenic changes in cannabis smokers, potentially enabling screening protocols similar to those used for tobacco smokers. If validated, such biomarkers could allow personalized risk assessment and targeted intervention. Insurance companies may begin incorporating cannabis use into health risk assessments. Some life insurance underwriters already ask about cannabis consumption frequency, and health insurers may follow. This development could create financial incentives for consumers to switch to lower-risk consumption methods or reduce use frequency. Litigation risk will influence corporate behavior. Legal experts anticipate that plaintiff attorneys will monitor epidemiological research for evidence supporting product liability claims. Cannabis companies are consulting with law firms that defended tobacco manufacturers to develop legal strategies and risk mitigation approaches. Some operators are considering voluntary warning enhancements beyond regulatory requirements to demonstrate reasonable care. International research will contribute important evidence. The European Respiratory Society is coordinating a multi-country study across 12 nations examining cannabis smoke exposure and lung cancer incidence. The study benefits from healthcare systems with comprehensive medical records and lower tobacco co-use rates than the United States. Results are expected in 2028.

Further Reading

• National Academies of Sciences, Engineering, and Medicine: "The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research" (2017) - https://nap.nationalacademies.org/catalog/24625/the-health-effects-of-cannabis-and-cannabinoids-the-current-state
• National Institute on Drug Abuse: "Marijuana Research Report: What are marijuana's effects on lung health?" - https://nida.nih.gov/publications/research-reports/marijuana/what-are-marijuanas-effects-lung-health
• American Lung Association: "Marijuana and Lung Health" policy statement - https://www.lung.org/quit-smoking/smoking-facts/health-effects/marijuana-and-lung-health
• Tashkin DP: "Effects of marijuana smoking on the lung" in Annals of the American Thoracic Society (2013) - https://www.atsjournals.org/doi/full/10.1513/AnnalsATS.201212-127FR
• U.S. Drug Enforcement Administration: Notice of Proposed Rulemaking on cannabis rescheduling - https://www.federalregister.gov/cannabis-scheduling
• California Bureau of Cannabis Control: Medicinal and Adult-Use Cannabis Regulation and Safety Act regulations - https://cannabis.ca.gov/laws-regulations/
• Colorado Department of Revenue Marijuana Enforcement Division: Rules and statutes - https://sbg.colorado.gov/med
• Substance Abuse and Mental Health Services Administration: National Survey on Drug Use and Health - https://www.samhsa.gov/data/data-we-collect/nsduh-national-survey-drug-use-and-health
• American Cancer Society: "Marijuana and Cancer" - https://www.cancer.org/cancer/risk-prevention/marijuana.html
• Centers for Disease Control and Prevention: "What We Know About Marijuana" - https://www.cdc.gov/marijuana/health-effects/index.html