Editing Effects of cannabis (section)

===Related to smoking===
[[File:Ganja Smoking - Gangasagar Fair Transit Camp - Kolkata 2013-01-12 2646.JPG|thumb|right|250px|A man smoking cannabis in [[Kolkata, India]]]]
As of 2025, no high-quality evidence has been found linking cannabis smoking to lung cancer, despite cannabis smoke having similar properties to tobacco smoke. Why this is the case remains unclear. Various studies have speculated that differences in patterns of use compared to tobacco could account for the difference, as well as the anti-inflammatory properties of certain cannabinoids. The health effects of cannabis smoke are an area of active study.

A 2007 study found that while [[tobacco smoking|tobacco]] and cannabis smoke are quite similar, cannabis smoke contained higher amounts of [[ammonia]], [[hydrogen cyanide]], and [[nitrogen oxides]], but lower levels of [[carcinogenic]] [[polycyclic aromatic hydrocarbon]]s (PAHs).<ref name="MoirRickert">{{cite journal | vauthors = Moir D, Rickert WS, Levasseur G, Larose Y, Maertens R, White P, Desjardins S | title = A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions | journal = Chemical Research in Toxicology | volume = 21 | issue = 2 | pages = 494–502 | date = February 2008 | pmid = 18062674 | doi = 10.1021/tx700275p | doi-access = free }}</ref> This study found that directly inhaled cannabis smoke contained as much as 20 times as much ammonia and 5 times as much hydrogen cyanide as tobacco smoke and compared the properties of both mainstream and sidestream (smoke emitted from a smouldering 'joint' or 'cone') smoke.<ref name="MoirRickert" /> Mainstream cannabis smoke was found to contain higher concentrations of selected polycyclic aromatic hydrocarbons (PAHs) than sidestream tobacco smoke.<ref name="MoirRickert" /> However, other studies have found much lower disparities in ammonia and hydrogen cyanide between cannabis and tobacco, and that some other constituents (such as polonium-210, lead, arsenic, nicotine, and tobacco-specific nitrosamines) are either lower or non-existent in cannabis smoke.<ref>{{cite book |last=Institute of Medicine |date=1982 |title=Marijuana and Health |url=https://archive.org/details/marijuanahealthr0000inst |location=Washington, D.C. |publisher=The National Academies Press |doi=10.17226/18942 |isbn=978-0-309-03236-0 |url-access=registration }}</ref><ref>{{cite web |url=http://www.acsa2000.net/HealthAlert/radioactive_tobacco.html |title=Radioactive Tobacco |author=Malmo-Levine, David |date=2 January 2002 |website=acsa2000.net |url-status=dead |archive-url=https://web.archive.org/web/20130112032208/http://www.acsa2000.net/HealthAlert/radioactive_tobacco.html |archive-date=12 January 2013 }}</ref> A 2021 [[longitudinal study]] conducted among populations of [[HIV-positive people|HIV-positive]] and [[HIV-negative]] adults found that smoke-related [[carcinogenic]] [[toxicant]]s and [[biomarker]]s detected in tobacco smokers were also detected in exclusive cannabis smokers, including [[carbon monoxide]] (CO), [[polycyclic aromatic hydrocarbons]] (PAHs), [[aldehydes]] (such as [[acrolein]]), [[acrylonitrile]] and [[acrylamide]] [[metabolites]], but exposures are lower compared with tobacco or dual smokers.<ref name="EClinicalMedicine">{{cite journal |last1=Lorenz |first1=David R. |last2=Misra |first2=Vika |last3=Chettimada |first3=Sukrutha |last4=Uno |first4=Hajime |last5=Wang |first5=Lanqing |last6=Blount |first6=Benjamin C. |last7=De Jesus |first7=Victor R. |last8=Gelman |first8=Benjamin B. |last9=Morgello |first9=Susan |last10=Wolinsky |first10=Steven M. |last11=Gabuzda |first11=Dana |date=January 2021 |title=Acrolein and other toxicant exposures in relation to cardiovascular disease among marijuana and tobacco smokers in a longitudinal cohort of HIV-positive and negative adults |url=https://www.thelancet.com/action/showPdf?pii=S2589-5370%2820%2930441-7 |format=PDF |journal=eClinicalMedicine |publisher=[[Elsevier]] |volume=31 |issue=100697 |page=100697 |doi=10.1016/j.eclinm.2020.100697 |doi-access=free |pmc=7846668 |pmid=33554087 |s2cid=231802821 |access-date=7 September 2021 |archive-date=20 April 2023 |archive-url=https://web.archive.org/web/20230420131252/https://www.thelancet.com/action/showPdf?pii=S2589-5370%2820%2930441-7 |url-status=live }}</ref> Increased levels of acrolein exposure by tobacco smoking but not exclusive cannabis smoking were detected both in HIV-positive and HIV-negative adults, and contribute to increased diagnoses of [[cardiovascular diseases]] and [[respiratory diseases]] among tobacco smokers.<ref name="EClinicalMedicine" />

Cannabis smoke contains thousands of organic and inorganic chemical compounds. This [[Tar (tobacco residue)|tar]] is chemically similar to that found in tobacco smoke or cigars.<ref>{{cite journal | vauthors = Hashibe M, Straif K, Tashkin DP, Morgenstern H, Greenland S, Zhang ZF | title = Epidemiologic review of marijuana use and cancer risk | journal = Alcohol | volume = 35 | issue = 3 | pages = 265–75 | date = April 2005 | pmid = 16054989 | doi = 10.1016/j.alcohol.2005.04.008 }}</ref> Over fifty known [[carcinogen]]s have been identified in cannabis smoke.<ref>{{Cite journal | title = Does smoking cannabis cause cancer? | publisher = Cancer Research UK | date = 20 September 2010 | url = http://cancerhelp.cancerresearchuk.org/about-cancer/cancer-questions/does-smoking-cannabis-cause-cancer | access-date = 23 June 2012 | url-status=dead | archive-url = https://web.archive.org/web/20120729115046/http://cancerhelp.cancerresearchuk.org/about-cancer/cancer-questions/does-smoking-cannabis-cause-cancer | archive-date = 29 July 2012 }}</ref> These include nitrosamines, reactive aldehydes, and polycylic hydrocarbons, including benz[a]pyrene.<ref>{{Cite journal |last=Tashkin |first=Donald |name-list-style=vanc |date=March 1997 |title=Effects of marijuana on the lung and its immune defenses |publisher=UCLA School of Medicine |url=http://www.ukcia.org/research/EffectsOfMarijuanaOnLungAndImmuneDefenses.php |access-date=23 June 2012 |archive-date=23 June 2012 |archive-url=https://web.archive.org/web/20120623140306/http://www.ukcia.org/research/EffectsOfMarijuanaOnLungAndImmuneDefenses.php |url-status=live }}</ref>  Cannabis smoke was listed as a cancer agent in California in 2009.<ref>{{cite web |url=http://oehha.ca.gov/prop65/prop65_list/files/p65single072012.pdf |title=Chemicals known to the state to cause cancer or reproductive toxicity |publisher=ca.gov |date=20 July 2012 |access-date=8 January 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130120030810/http://oehha.ca.gov/prop65/prop65_list/files/p65single072012.pdf |archive-date=20 January 2013 }}</ref>  A study by the [[British Lung Foundation]] published in 2012 identifies cannabis smoke as a carcinogen and also finds awareness of the danger is low compared with the high awareness of the dangers of smoking tobacco particularly among younger users. Other observations include possible increased risk from each cigarette; lack of research on the effect of cannabis smoke alone; low rate of addiction compared to tobacco; and episodic nature of cannabis use compared to steady frequent smoking of tobacco.<ref name="BLA2012">{{Cite journal |url=http://www.blf.org.uk/Files/8ec171b2-9b7e-49d9-b3b1-a07e00f11c05/ |title=The impact of cannabis on your lung |publisher=British Lung Association |date=June 2012 |access-date=8 January 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130927183248/http://www.blf.org.uk/Files/8ec171b2-9b7e-49d9-b3b1-a07e00f11c05/ |archive-date=27 September 2013 }}</ref>{{unreliable medical source|date=November 2019}}<!-- Should this study and the complaints about it all be removed and just replaced with a reliable study?--> Professor [[David Nutt]], a UK drug expert, points out that the study cited by the British Lung Foundation has been accused of both "false reasoning" and "incorrect methodology". Further, he notes that other studies have failed to connect cannabis with lung cancer, and accuses the BLF of "scaremongering over cannabis".<ref>{{Cite journal |last=Le |first=Bryan |name-list-style=vanc |url=http://www.thefix.com/content/david-nutt-cannabis-carcinogenic90225 |title=Drug prof slams pot lung-danger claims |publisher=The Fix |date=8 June 2012 |access-date=9 January 2013 |archive-date=30 December 2012 |archive-url=https://web.archive.org/web/20121230000132/http://www.thefix.com/content/david-nutt-cannabis-carcinogenic90225 |url-status=live }}</ref>