Cannabis Smoking in 2015
2015; Elsevier BV; Volume: 148; Issue: 3 Linguagem: Inglês
10.1378/chest.15-0447
ISSN1931-3543
AutoresJason Biehl, Ellen L. Burnham,
Tópico(s)Biochemical Analysis and Sensing Techniques
ResumoRecent legislative successes allowing expanded access to recreational and medicinal cannabis have been associated with its increased use by the public, despite continued debates regarding its safety within the medical and scientific communities. Despite legislative changes, cannabis is most commonly used by smoking, although alternatives to inhalation have also emerged. Moreover, the composition of commercially available cannabis has dramatically changed in recent years. Therefore, developing sound scientific information regarding its impact on lung health is imperative, particularly because published data conducted prior to widespread legalization are conflicting and inconclusive. In this commentary, we delineate major observations of epidemiologic investigations examining cannabis use and the potential associated development of airways disease and lung cancer to highlight gaps in pulmonary knowledge. Additionally, we review major histopathologic alterations related to smoked cannabis and define specific areas in animal models and human clinical translational investigations that could benefit from additional development. Given that cannabis has an ongoing classification as a schedule I medication, federal funding to support investigations of modern cannabis use in terms of medicinal efficacy and safety profile on lung health have been elusive. It is clear, however, that the effects of inhaled cannabis on lung health remain uncertain and given increasing use patterns, are worthy of further investigation. Recent legislative successes allowing expanded access to recreational and medicinal cannabis have been associated with its increased use by the public, despite continued debates regarding its safety within the medical and scientific communities. Despite legislative changes, cannabis is most commonly used by smoking, although alternatives to inhalation have also emerged. Moreover, the composition of commercially available cannabis has dramatically changed in recent years. Therefore, developing sound scientific information regarding its impact on lung health is imperative, particularly because published data conducted prior to widespread legalization are conflicting and inconclusive. In this commentary, we delineate major observations of epidemiologic investigations examining cannabis use and the potential associated development of airways disease and lung cancer to highlight gaps in pulmonary knowledge. Additionally, we review major histopathologic alterations related to smoked cannabis and define specific areas in animal models and human clinical translational investigations that could benefit from additional development. Given that cannabis has an ongoing classification as a schedule I medication, federal funding to support investigations of modern cannabis use in terms of medicinal efficacy and safety profile on lung health have been elusive. It is clear, however, that the effects of inhaled cannabis on lung health remain uncertain and given increasing use patterns, are worthy of further investigation. Over the past decade, US cannabis legislation has changed dramatically at the state level, enabling sales for medicinal and recreational use. Although not necessarily causal, paralleling these legislative changes, per capita cannabis consumption has also risen.1Kilmer B Caulkins JP Midgette G et al.Before the grand opening: measuring Washington State's marijuana market in the last year before legalized commercial sales. RAND Corporation website.http://www.rand.org/content/dam/rand/pubs/research_reports/RR400/RR466/RAND_RR466.pdf. Published 2013Google Scholar-2Light MK Orens A Lewandowski B et al.Market size and demand for marijuana in Colorado. Marijuana Policy Group, Colorado Department of Revenue. State of Colorado website.https://www.colorado.gov/pacific/sites/default/files/Market%20Size%20and%20Demand%20Study,%20July%209,%202014%5B1%5D.pdfGoogle Scholar In 2013, 650,000 Washington State residents (9% of the population), and 393,000 Colorado residents (7.3% of the population) reported using cannabis at least monthly. Among these regular cannabis users, 25% to 32% used cannabis daily, with an average of 3.5 to 3.9 joints smoked per day.1Kilmer B Caulkins JP Midgette G et al.Before the grand opening: measuring Washington State's marijuana market in the last year before legalized commercial sales. RAND Corporation website.http://www.rand.org/content/dam/rand/pubs/research_reports/RR400/RR466/RAND_RR466.pdf. Published 2013Google Scholar2Light MK Orens A Lewandowski B et al.Market size and demand for marijuana in Colorado. Marijuana Policy Group, Colorado Department of Revenue. State of Colorado website.https://www.colorado.gov/pacific/sites/default/files/Market%20Size%20and%20Demand%20Study,%20July%209,%202014%5B1%5D.pdfGoogle Scholar More worrisome, legalization of medicinal marijuana has been associated with both decreased risk perceptions and increased use among Colorado youth compared with 34 states without medicinal laws.3Schuermeyer J Salomonsen-Sautel S Price RK et al.Temporal trends in marijuana attitudes, availability and use in Colorado compared to non-medical marijuana states: 2003-11.Drug Alcohol Depend. 2014; 140: 145-155Abstract Full Text Full Text PDF PubMed Scopus (193) Google Scholar Because smoking remains the most prevalent route of cannabis consumption,4Tashkin DP Effects of marijuana smoking on the lung.Ann Am Thorac Soc. 2013; 10: 239-247Crossref PubMed Scopus (167) Google Scholar its increasingly widespread use and social acceptability raise concerns regarding its future impact on lung health in the United States. In this commentary, we highlight limitations in understanding the effects of inhaled cannabis on lung health based on epidemiologic investigations regarding the relationship of cannabis to airways diseases and lung cancer. We also focus on areas in animal model and human clinical and translational research where novel investigations can broaden the scope of current research knowledge. To understand the potential clinical impact of inhaled cannabis use on lung health, it is important to appreciate the plant's complexity and mechanisms of action.5Brenneisen R Chemistry and analysis of phytocannabinoids and other Cannabis constituents.in: ElSohly MA Forensic Science and Medicine: Marijuana and the Cannabinoids. Humana Press, Totowa, NJ2011: 17-49Google Scholar Cannabis contains 483 unique compounds, including 66 cannabinoids. Ten subclasses of cannabinoids have been characterized, including Δ-9-tetrahydrocannabinols (THCs) and seven subclasses of cannabidiols (CBDs).6ElSohly MA Slade D Chemical constituents of marijuana: the complex mixture of natural cannabinoids.Life Sci. 2005; 78: 539-548Crossref PubMed Scopus (700) Google Scholar THCs are the primary psychoactive substances, with pharmacologic properties including euphoria and analgesia. In contrast, CBDs possess anxiolytic properties that counter effects of THC. Two cannabinoid receptors, G-protein-coupled transmembrane proteins negatively coupled to adenylyl cyclase termed CB1 and CB2, have been identified in humans.7Croxford JL Yamamura T Cannabinoids and the immune system: potential for the treatment of inflammatory diseases?.J Neuroimmunol. 2005; 166: 3-18Abstract Full Text Full Text PDF PubMed Scopus (208) Google Scholar These receptors are activated by both endogenous endocannabinoids (a family of locally produced, phospholipid-derived substances8Després JP The endocannabinoid system: a new target for the regulation of energy balance and metabolism.Crit Pathw Cardiol. 2007; 6: 46-50Crossref PubMed Scopus (30) Google Scholar) and many exogenous cannabinoids. CB1 receptors are predominantly localized on neurons within the CNS where they mediate the psychogenic effects of cannabis and are found in the autonomic innervation of airway smooth muscle, whereas CB2 receptors are primarily localized on immune cells. The focus of epidemiologic data published in the past 15 years has primarily been on understanding the relationship between cannabis use and airways diseases9Aldington S Williams M Nowitz M et al.Effects of cannabis on pulmonary structure, function and symptoms..Thorax. 2007; 62: 1058-1063Crossref PubMed Scopus (215) Google Scholar, 10Hancox RJ Poulton R Ely M et al.Effects of cannabis on lung function: a population-based cohort study.Eur Respir J. 2010; 35: 42-47Crossref PubMed Scopus (129) Google Scholar, 11Kempker JA Honig EG Martin GS The effects of marijuana exposure on expiratory airflow. A study of adults who participated in the U.S. National Health and Nutrition Examination Study.Ann Am Thorac Soc. 2015; 12: 135-141Crossref PubMed Scopus (52) Google Scholar, 12Moore BA Augustson EM Moser RP Budney AJ Respiratory effects of marijuana and tobacco use in a US sample.J Gen Intern Med. 2005; 20: 33-37Crossref PubMed Scopus (151) Google Scholar, 13Pletcher MJ Vittinghoff E Kalhan R et al.Association between marijuana exposure and pulmonary function over 20 years.JAMA. 2012; 307: 173-181Crossref PubMed Scopus (179) Google Scholar, 14Tashkin DP Simmons MS Sherrill DL Coulson AH Heavy habitual marijuana smoking does not cause an accelerated decline in FEV1 with age..Am J Respir Crit Care Med. 1997; 155: 141-148Crossref PubMed Scopus (90) Google Scholar, 15Taylor DR Fergusson DM Milne BJ et al.A longitudinal study of the effects of tobacco and cannabis exposure on lung function in young adults.Addiction. 2002; 97: 1055-1061Crossref PubMed Scopus (150) Google Scholar (Table 1). Smoking cannabis has been associated with an increase in total lung capacity and FVC,9Aldington S Williams M Nowitz M et al.Effects of cannabis on pulmonary structure, function and symptoms..Thorax. 2007; 62: 1058-1063Crossref PubMed Scopus (215) Google Scholar10Hancox RJ Poulton R Ely M et al.Effects of cannabis on lung function: a population-based cohort study.Eur Respir J. 2010; 35: 42-47Crossref PubMed Scopus (129) Google Scholar13Pletcher MJ Vittinghoff E Kalhan R et al.Association between marijuana exposure and pulmonary function over 20 years.JAMA. 2012; 307: 173-181Crossref PubMed Scopus (179) Google Scholar potentially resulting from deep-breathing maneuvers of users.9Aldington S Williams M Nowitz M et al.Effects of cannabis on pulmonary structure, function and symptoms..Thorax. 2007; 62: 1058-1063Crossref PubMed Scopus (215) Google Scholar10Hancox RJ Poulton R Ely M et al.Effects of cannabis on lung function: a population-based cohort study.Eur Respir J. 2010; 35: 42-47Crossref PubMed Scopus (129) Google Scholar In the setting of heavy, prolonged cannabis use (typically > 20 joint-years),9Aldington S Williams M Nowitz M et al.Effects of cannabis on pulmonary structure, function and symptoms..Thorax. 2007; 62: 1058-1063Crossref PubMed Scopus (215) Google Scholar11Kempker JA Honig EG Martin GS The effects of marijuana exposure on expiratory airflow. A study of adults who participated in the U.S. National Health and Nutrition Examination Study.Ann Am Thorac Soc. 2015; 12: 135-141Crossref PubMed Scopus (52) Google Scholar13Pletcher MJ Vittinghoff E Kalhan R et al.Association between marijuana exposure and pulmonary function over 20 years.JAMA. 2012; 307: 173-181Crossref PubMed Scopus (179) Google Scholar15Taylor DR Fergusson DM Milne BJ et al.A longitudinal study of the effects of tobacco and cannabis exposure on lung function in young adults.Addiction. 2002; 97: 1055-1061Crossref PubMed Scopus (150) Google Scholar a dose-response association between development of airflow limitation (either decreased FEV1 or decreased FEV1/FVC) has also been reported, the latter possibly attributable to increased FVC. Symptoms referable to chronic bronchitis, including daily cough, phlegm production, and wheeze, have been noted in cannabis smokers after less-intense use.9Aldington S Williams M Nowitz M et al.Effects of cannabis on pulmonary structure, function and symptoms..Thorax. 2007; 62: 1058-1063Crossref PubMed Scopus (215) Google Scholar11Kempker JA Honig EG Martin GS The effects of marijuana exposure on expiratory airflow. A study of adults who participated in the U.S. National Health and Nutrition Examination Study.Ann Am Thorac Soc. 2015; 12: 135-141Crossref PubMed Scopus (52) Google Scholar12Moore BA Augustson EM Moser RP Budney AJ Respiratory effects of marijuana and tobacco use in a US sample.J Gen Intern Med. 2005; 20: 33-37Crossref PubMed Scopus (151) Google Scholar15Taylor DR Fergusson DM Milne BJ et al.A longitudinal study of the effects of tobacco and cannabis exposure on lung function in young adults.Addiction. 2002; 97: 1055-1061Crossref PubMed Scopus (150) Google Scholar In terms of lung cancer, epidemiologic data suggesting an association between increased duration and quantity of cannabis exposure with higher odds of lung malignancy development16Aldington S Harwood M Cox B Cannabis and Respiratory Disease Research Group et al.Cannabis use and risk of lung cancer: a case-control study.Eur Respir J. 2008; 31: 280-286Crossref PubMed Scopus (187) Google Scholar, 17Callaghan RC Allebeck P Sidorchuk A Marijuana use and risk of lung cancer: a 40-year cohort study.Cancer Causes Control. 2013; 24: 1811-1820Crossref PubMed Scopus (146) Google Scholar, 18Han B Gfroerer JC Colliver JD Associations between duration of illicit drug use and health conditions: results from the 2005-2007 national surveys on drug use and health.Ann Epidemiol. 2010; 20: 289-297Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar have not been con-sistent19Zhang LR Morgenstern H Greenland S Cannabis and Respiratory Disease Research Group of New Zealand et al.Cannabis smoking and lung cancer risk: pooled analysis in the International Lung Cancer Consortium.Int J Cancer. 2015; 136: 894-903Crossref PubMed Scopus (110) Google Scholar (Table 2). Together, these epidemiologic data imply that modest consumption of cannabis may have a minimal impact on lung health. Importantly, however, these data were largely collected prior to recent legislative changes; therefore, the relatively small percentage of heavy cannabis consumers surveyed may not reflect emerging trends in cannabis use.TABLE 1Epidemiologic Studies of Cannabis Effects on AirwaysStudy TypeCohort Size, Location, Racial FeaturesCannabis Users in Cohort, With and Without TobaccoHow Cannabis Use Assessed and QuantitatedaPack-y = 1 pack/d of tobacco cigarettes × 20 cigarettes/pack × 365 d/y; joint-y = 1 joint/day × 365 d/y.Approximate Cannabis Use Among Cannabis UsersYears of Cannabis UseMain Findings and ObservationsReferenceLongitudinal (8-y period)394 United States 100% white131 cannabis 112 cannabis + tobacco 65 tobacco, 86 nonsmokersDetailed drug questionnaires endorsed by ATS, NHLBI, and NIDA3-4 joints/d or 45-56 joint-y (first visit)1983-1993No ↓FEV1 over 8 y associated with cannabis smoking; no additive effect of cannabis and tobacco on FEV1; only 20 of 394 followed full 8 y14Longitudinal (data obtained from subjects at age 18, 21, and 26 y)900 New Zealand Race not reported50% occasional cannabis users 10% cannabis dependent (DSM-IV) Unspecified number of tobacco smokersNo. occasions cannabis used in preceding 12 mo by surveyAt age 18 y, 22 of 859 subjects (2.5%) cumulatively used cannabis > 300 d At age 26, 108 of 930 subjects (11.6%) had used> 300 d1990-1998Subjects at risk for ↓FEV1/FVC either used cannabis on > 900 occasions or smoked > 20 cigarettes/d; additive effects from cannabis and tobacco use on ↓FEV1/FVC15Cross-sectional6,728 United States (NHANES III) 68% white94 cannabis 320 cannabis+ tobacco 1,525 tobacco 4,789 nonsmokersQuestionnaires on lifetime use of cannabis and past month use of cannabisCannabis smoked 10.2 d/mo; 16% near-daily cannabis users; 77% also smoked tobacco1988, 1994After controlling for tobacco, cannabis use was associated with chronic bronchitis, cough, phlegm production, and wheezing but not ↓FEV1/FVC ≤ 70%12Cross-sectional339 New Zealand 90% white75 cannabis 91 cannabis+ tobacco 92 tobacco 81 nonsmokersQuestionnaires on lifetime cannabis use, joint-yAverage 46-54 joint-y among cannabis users; wide CIsBefore 2007Dose-response relationship of joint-y cannabis smoking and ↓FEV1/FVC, ↓sGaw, ↓TLC; one joint of cannabis had equal effects on ↓FEV1/FVC as 2.5-5 tobacco cigarettes9Longitudinal (data obtained from subjects at age 18, 21, 26, and 32 y)1,037 New Zealand European ethnicity248 cannabis 435 cannabis+ tobacco 58 tobacco 226 nonsmokersQuestionnaires on No. times cannabis used in past year in joint-y since age 17 y; tobacco smoked/d23% (222 of 967) with > 1 joint-y (110 of 222 [50%] with > 10 pack-y tobacco) 48% (461 of 967) with ≤ 1 joint-y (82 of 461 [18%] with >10 pack-y tobacco)1980-2004Longitudinal analyses (adjusted) in cannabis users revealed ↓FVC; in tobacco users, ↓FEV1, FEV1/FVC; cannabis-only smokers had ↓TLC, Va, ↓sGaw; only 40 of 967 in cohort smoked > 1 joint-y and did not smoke cigarettes10Longitudinal (data obtained over a 20-y period)5,115 United States 48% white and 51% black795 cannabis 1,065 cannabis + tobacco 851 tobacco, 2,305 nonsmokersQuestionnaires on lifetime exposure in joint-y; joints/d in past 30 d; tobacco in pack-y2-3 d of use in past 30 d; 0.9-1.5 joint-y1985-2005At > 20 joint-y cannabis, ↓FEV1, ↑FVC; trend for ↓FEV1 > 10 joint-y; tobacco smoking had stronger impact on airflow limitation than cannabis13Cross-sectional6,723 United States (NHANES III) 67% white and 12% black184 cannabis 671 cannabis+ tobacco 2,975 tobacco 2,893 nonsmokersQuestionnaires on lifetime exposure in joint-y; past 30-d cannabis use; tobacco in pack-yAmong current cannabis users (tobacco and nontobacco users), 15.8 joint-y 12.0 d of use/mo2007-2010In logistic regression analyses, > 20 joint-y history predicted ↓FEV1/FVC ≤ 70%, as did tobacco use between 1 and 5 pack-y; current cannabis users with ↑respiratory symptoms associated with longer duration and more intense use11ATS = American Thoracic Society; DSM-IV = Diagnostic and Statistical Manual, Fourth Edition; NHANES = National Health and Nutrition Examination Survey; NHLBI = National Heart, Lung, and Blood Institute; NIDA = National Institute on Drug Abuse; sGaw = specific airway conductance; TLC = total lung capacity; VA = alveolar volume.a Pack-y = 1 pack/d of tobacco cigarettes × 20 cigarettes/pack × 365 d/y; joint-y = 1 joint/day × 365 d/y. Open table in a new tab TABLE 2Epidemiologic Studies of Cannabis Association With Lung CancerStudy TypeCohort Size, Location, Racial FeaturesSubjects With Cancer and Control SubjectsHow Cannabis Use Assessed and QuantitatedaPack-y = 1 pack/d tobacco cigarettes × 20 cigarettes/pack × 365 d/y; joint-y = 1 joint/d × 365 d/y.Approximate Cannabis Use Among Cannabis SmokersYears of Cannabis UseMain Findings and ObservationsReferenceCase-control cohort403 New Zealand residents79 lung cancer 324 controlDuration of cannabis use, joint-y, pack-y tobacco use12 of 79 cases with > 10.5 joint-y compared with four of 324 control subjects2001-2005After adjustment for family history and pack-y tobacco, relative risk for lung cancer was 1.08 (95% CI, 1.02-1.15) per joint-y cannabis smoking16Cross-sectional29,195 National surveys on drug use and health, United States Adjusted for race/ethnicityLung cancer by duration of cannabis use: Never= 9 ≤ 1 y = 23 2-10 y= 23 >11 y = 67Duration of cannabis use (y); daily tobacco use also ascertained for use in modelsNot reported2005-2007After adjustment, cannabis use of > 11 y associated with OR for lung cancer development of 7.87 (95% CI, 1.28-48.4)18Longitudinal evaluation over 40 y of single cohort49,321 Swedish men born in 1949-1951 conscripted in 1969-1970 for military service189 lung cancer 49,132 controlEver or never use of cannabis, lifetime frequency of cannabis use, No. tobacco cigarettes per day5,156 ever cannabis users 831 of 5,156 (16%) reported > 50 times of use 515 of 831 (62%) also smoked > 10 cigarettes/d1969-2009After adjusting for tobacco and alcohol consumption, smoking cannabis > 50 times was associated with a hazard ratio of 2.12 (95% CI, 1.08-4.14) for lung cancer development over 40 y; ever use was not associated with an increased hazard ratio for lung cancer17Analysis of pooled data from six case-control studies5,144 International Lung Cancer Consortium: United States, Europe, New Zealand 79% white, 11% black2,159 lung cancer 2,985 controlLifetime cannabis use, joint-y; 86% of habitual cigarette smokers also used cannabis10% of patients with lung cancer were habitual cannabis users 6% with > 10 joint-y1999-2013Little or no association between intensity, duration, or cumulative use of cannabis and risk of lung cancer development; pooled OR for association between cannabis smoking (habitual vs nonhabitual) and lung cancer risk was 0.95 (95% CI, 0.66-1.38)19a Pack-y = 1 pack/d tobacco cigarettes × 20 cigarettes/pack × 365 d/y; joint-y = 1 joint/d × 365 d/y. Open table in a new tab ATS = American Thoracic Society; DSM-IV = Diagnostic and Statistical Manual, Fourth Edition; NHANES = National Health and Nutrition Examination Survey; NHLBI = National Heart, Lung, and Blood Institute; NIDA = National Institute on Drug Abuse; sGaw = specific airway conductance; TLC = total lung capacity; VA = alveolar volume. Cannabis consumers in most epidemiologic studies and users in general rarely consume only cannabis and no tobacco, a fact that limits understanding cannabis-specific effects on lung health. Moreover, in certain populations, cannabis often is smoked simultaneously with tobacco. Reasons for this preference include the fact that the combustion of both cannabis and tobacco together increases the vaporization efficiency of THC per gram of cannabis and may contribute to enhanced psychogenic effects compared with smoking cannabis alone.20Van der Kooy F Pomahacova B Verpoorte R Cannabis smoke condensate II: influence of tobacco on tetrahydrocannabinol levels.Inhal Toxicol. 2009; 21: 87-90Crossref PubMed Scopus (33) Google Scholar This suggests that concurrent use of tobacco and cannabis could compound effects on airways pathology, and indeed, one study reported additive effects.15Taylor DR Fergusson DM Milne BJ et al.A longitudinal study of the effects of tobacco and cannabis exposure on lung function in young adults.Addiction. 2002; 97: 1055-1061Crossref PubMed Scopus (150) Google Scholar Therefore, accurate histories regarding both cannabis and tobacco use along with additional information regarding methods of use are important clinically and in scientific investigations. Routine spirometric monitoring of heavy or long-term cannabis users also appears to be warranted given the prevalence of airflow limitation among the heaviest users11Kempker JA Honig EG Martin GS The effects of marijuana exposure on expiratory airflow. A study of adults who participated in the U.S. National Health and Nutrition Examination Study.Ann Am Thorac Soc. 2015; 12: 135-141Crossref PubMed Scopus (52) Google Scholar and limited longitudinal data in heavy users.13Pletcher MJ Vittinghoff E Kalhan R et al.Association between marijuana exposure and pulmonary function over 20 years.JAMA. 2012; 307: 173-181Crossref PubMed Scopus (179) Google Scholar Finally, as with tobacco use, cannabis use is more prevalent in individuals who use and abuse other drugs, including alcohol.21Degenhardt L Hall W Lynskey M The relationship between cannabis use and other substance use in the general population.Drug Alcohol Depend. 2001; 64: 319-327Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar Identification of cannabis use in clinical or research settings should, therefore, prompt screening for unhealthy use of other drugs and alcohol. Epidemiologic studies have indicated that smoking remains the exceedingly most common route of cannabis use. The preference for smoking compared with oral or topical use may result from superior bioavailability and relatively quick onset of effects.22Grotenhermen F Pharmacokinetics and pharmacodynamics of cannabinoids.Clin Pharmacokinet. 2003; 42: 327-360Crossref PubMed Scopus (891) Google Scholar Numerous methods to smoke cannabis currently exist (Fig 1); additionally, a variety of mechanisms for noncombusted cannabis inhalation have also increased in popularity, such as vaporizer devices that aerosolize cannabinoids by heating them to below burning temperature (Table 3). Vaporized use of cannabis has received increased interest both in the medical literature and by medicinal cannabis supporters in hopes to achieve the therapeutic benefits of cannabis without the potentially adverse effects from by-products of cannabis combustion. The use of portable, battery-operated vaporization devices has also been increasing, particularly among youth.23Goldstein JE Students find way to secretly smoke marijuana in class. CBS Denver website.http://denver.cbslocal.com/2014/02/05/students-find-way-to-secretly-smoke-marijuana-in-class. Published February 2, 2014Google Scholar Clinicians caring for patients reporting the use of vaporized or other noncombusted cannabis products need to be aware that these devices are touted as eliminating carcinogenic combustion products common to both smoked cannabis and tobacco (eg, tar, acrolein). However, neither carcinogenic nor other downstream effects of vaporized cannabis on airways have been rigorously tested. Additionally, effects of potentially increased THC delivery from vaporizers or other devices on pulmonary immune function, particularly alveolar macrophage function, remain unknown. Investigations outside the United States with commercially available vaporization devices are presently establishing methods to test pharmacologic effects of vaporized CBD and THC24Solowij N Broyd SJ van Hell HH Hazekamp A A protocol for the delivery of cannabidiol (CBD) and combined CBD and A9-tetrahydrocannabinol (THC) by vaporisation.BMC Pharmacol Toxicol. 2014; 15: 58Crossref PubMed Scopus (34) Google Scholar; however, future investigations to delineate safety of vaporization or other routes of use on lung health in the United States will remain limited given the schedule I controlled status of cannabis.TABLE 3Rationale and Disadvantages of Various Inhaled Cannabis MethodsMode of Inhaled CannabisAdvantagesDisadvantagesBluntInexpensive, effects of given quantity cannabis may be enhanced relative to consumption by other methodsMade from tobacco or cigar paper, smoke harsh in quality, difficult to rollBongWater can trap some of the more harmful products of combustionExpensive, easily broken, not as porTABLEDabbingCondensed product is easy to conceal, potent psychogenic effectsBurn injury common related to volatile agents used to solubilize condensed cannabis productsG-penMore discreet, no smoke odor or visible smoke, no products of combustionLittle regulation of ingredients, use rising among youthHookahCan smoke with multiple people, higher volume of smoke, flavors availableProduct mixed with tobacco, combustion products potentially more damaging to the lungsJointSmall and convenientFragile, difficult to rollPipeProduct can be inhaled directly, producing more rapid psychogenic effectsGlass pipes can break, possible to inhale harmful resinVaporizerNo smoke odor, no products of combustionDevice relatively expensive, not porTABLE, little regulation of ingredientsSee also Figure 1. Open table in a new tab See also Figure 1. All epidemiologic studies mentioned quantitated cannabis use by self-report using validated surveys and, therefore, are subject to recall bias. For occasional See also Figure 1. cannabis users, such bias would not likely be problematic, but in daily users, cognitive impairment from cannabis has the potential to influence data accuracy. Additionally, subject candor and accuracy may have suffered from the illegal nature of cannabis during the time when or in the place where data were collected. Therefore, development of biomarkers enabling an accurate assessment of current and past cannabis use are urgently needed to objectively determine the dose of cannabis that may compromise lung health. Assays of urine (less commonly saliva or blood) are widely available and reliably confirm cannabis exposure.25Toennes SW Kauert GF Steinmeyer S Moeller MR Driving under the influence of drugs – evaluation of analytical data of drugs in oral fluid, serum and urine, and correlation with impairment symptoms.Forensic Sci Int. 2005; 152: 149-155Crossref PubMed Scopus (137) Google Scholar However, their accuracy may be influenced by the time elapsed since last cannabis use; furthermore, they do not provide a quantitative estimate of use. Accurate quantitation can be performed through liquid chromatography-tandem mass spectrometry, although this method is cumbersome for routine clinical applications.26Mercolini L Mandrioli R Protti M Conti M Serpelloni G Raggi MA Monitoring of chronic cannabis abuse: an LC-MS/MS method for hair analysis.J Pharm Biomed Anal. 2013; 76: 119-125Crossref PubMed Scopus (42) Google Scholar To address these limitations, portable and sensitive real-time methods, including the application of an electronic nose, are currently undergoing clinical testing to detect subtle body odors related to metabolic changes on the human skin surface that indicate cannabis consumption.27Voss A Witt K Kaschowitz T et al.Detecting cannabis use on the human skin surface via an electronic nose system.Sensors (Basel). 2014; 14: 13256-13272Crossref PubMed Scopus (26) Google Scholar Understanding the relationship of pulmonary pathophysiology and symptoms to changes in biomarkers quantifying cannabis exposure may help to establish a threshold for harmful cannabis use and help to set policies regulating drug sales. Excellent reviews have been published describing the res
Referência(s)