Marijuana effects on lungs, looking for the truth

I've read many studies on the research of marijuana on the lungs, brain, heart, etc.  From my findings, I have found that moderate smoking poses little risk to the body.  While I've ready pretty consistent reports on marijuana effects on the heart and brain, I read different articles about marijuana on the lungs everyday.  For example: The WHO did a study that concluded in 1998, that even among heavy smokers, marijuana posed minimal health risks to the lungs and was not associated with major lung diseases (http://news.bbc.co.uk/2/hi/science/nature/58013.stm).  I also have read that marijuana has not been proven and is unlikely to cause cancer due to its active ingredient, THC (http://www.washingtonpost.com/wp-dyn/content/article/2006/05/25/AR2006052501729_pf.html).  But, on the other hand I have read reports of marijuana being detrimental to the lungs even in moderation (http://www.medicalnewstoday.com/articles/94896.php).  I am unsure what to believe, especially because most media is biased either in favor of marijuana or against marijuana.  I have been an occasional marijuana smoker (2-3 times a week) for about a half of a year.  I just would like to know a doctor's perspective, as I am unsure what to believe at the moment.  I understand that emphysema is unlikely with marijuana due to the airways that it affects, but what about other serious lung diseases?  I am in fairly good shape, work out and try to run everyday, and don't plan on smoking past my college years.  I just would like to know, as a doctor, what you have seen in the field as far as severe medical complications (I am well aware of mild coughing/wheezing).  Thank you.

[National Jewish Health]

However, it is likely that smoking 2 to 3 joints weekly would be minimally harmful for the majority of individuals; the exception being those individuals who suffer from the condition, alpha-1 antitrypsin deficiency, that severely predisposes one to the early-in-life development of severe chronic obstructive pulmonary disease (COPD).

Authors Van Hoozen, B E. Cross, C E.
Institution Division of Pulmonary and Critical Care Medicine, University of
California at Davis, Sacramento 95817, USA.
Title Marijuana. Respiratory tract effects. [Review] [163 refs]
Source Clinical Reviews in Allergy & Immunology. 15(3):243-69, 1997.
Abstract Daily marijuana smoking has been clearly shown to have adverse effects on pulmonary function and produce respiratory symptomatology (cough, wheeze, and sputum production) similar to that of tobacco smokers.  Based on the tobacco experience, decrements in pulmonary function may be predictive of the future development of chronic obstructive pulmonary disease (COPD).  However, in the absence of alpha-1-antitrypsin deficiency, the habitual marijuana-only smoker would likely have to smoke 4-5 joints per day for a span of at least 30 yr in order to develop overt manifestations of COPD.  The mutagenic/carcinogenic properties of marijuana smoke are also well-established. The potential for induction of laryngeal, oropharyngeal, and possibly bronchogenic carcinoma from marijuana has been documented by several case reports and observational series.  Despite this, a relative risk ratio for the development of these tumors has not yet been quantified.  Based on a higher frequency of case reports for upper airway cancer compared to bronchogenic carcinoma, marijuana smoking may have a more deleterious effect on the upper respiratory tract.  However, this hypothesis remains speculative at best, pending confirmation by longitudinal studies. [References: 163]

The latest report in 2005 by Tashkin et all does indeed confirm the lack of an association of smoking marijuana and lung cancer.  However, there is substantial evidence that this substance causes lung damage and lung disease.  The following is a 2008 statement of the World Health Organization (WHO) on the adverse effects of marijuana.

World Health Organization (2008) Chronic health effects of cannabis use
• selective impairment of cognitive functioning which include the organization and integration of complex information involving various mechanisms of attention and memory processes;
• prolonged use may lead to greater impairment, which may not recover with cessation of use, and which could affect daily life functions;
• development of a cannabis dependence syndrome characterized by a loss of control over cannabis use is likely in chronic users;
• cannabis use can exacerbate schizophrenia in affected individuals;
• epithetial injury of the trachea and major bronchi is caused by long-term cannabis smoking;
• airway injury, lung inflammation, and impaired pulmonary defence against infection from persistent cannabis consumption over prolonged periods;
• heavy cannabis consumption is associated with a higher prevalence of symptoms of chronic bronchitis and a higher incidence of acute bronchitis than in the non-smoking cohort;
• cannabis used during pregnancy is associated with impairment in fetal development leading to a reduction in birth weight;
• cannabis use during pregnancy may lead to postnatal risk of rare forms of cancer although more research is needed in this area.

Marijuana Smokers Face Rapid Lung Destruction - As Much As 20 Years Ahead Of Tobacco Smokers

A study in a Wiley-Blackwell journal - Respirology - finds that the development of bullous lung disease occurs in marijuana smokers approximately 20 years earlier than tobacco smokers.

A condition often caused by exposure to toxic chemicals or long-term exposure to tobacco smoke, bullous lung disease (also known as bullae) is a condition where air trapped in the lungs causes obstruction to breathing and eventual destruction of the lungs.

At present, about 10% of young adults and 1% of the adult population smoke marijuana regularly. Researchers find that the mean age of marijuana-smoking patients with lung problems was 41, as opposed to the average age of 65 years for tobacco-smoking patients.

The study "Bullous Lung Disease due to Marijuana" also finds that the bullous lung disease can easily go undetected as patients suffering from the disease may show normal chest X-rays and lung functions. High-resolution CT scans revealed severe asymmetrical, variably sized bullae in the patients studied. However, chest X-rays and lung functions were normal in half of them.

Lead author Dr. Matthew Naughton says, "What is outstanding about this study is the relatively young ages of the lung disease patients, as well as the lack of abnormality on chest X-rays and lung functions in nearly half of the patients we tested."

He added, "Marijuana is inhaled as extremely hot fumes to the peak inspiration and held for as long as possible before slow exhalation. This predisposes to greater damage to the lungs and makes marijuana smokers are more prone to bullous disease as compared to cigarette smokers."

Patients who smoke marijuana inhale more and hold their breath four times longer than cigarette smokers. It is the breathing manoeuvres of marijuana smokers that serve to increase the concentration and pulmonary deposition of inhaled particulate matter - resulting in greater and more rapid lung destruction.

This paper is published in the January 2008 issue of Respirology. The abstract is available free online here.

About Respirology

Respirology is a journal of international standing, publishing peer-reviewed articles of scientific excellence in clinical and experimental respiratory biology and disease and its related fields of research including thoracic surgery, internal medicine, immunology, intensive and critical care, epidemiology, cell and molecular biology, pathology, pharmacology and physiology.

[Rob2008]

I believe it truley depends on the purity of the drug.   Pesticides and other chemicals can cause havoc with the brain.

[threefive79]

yes but with marijuana the drug is usually pure, sure there are some pesticides and fertilizers, but the drug is rarely laced and sold as regular marijuana.  we eat fertilizers and pesticides that farmers put on fruits and vegetables anyway, kfc feeds their chickens chemicals to grow abnormally, i'm sure the pesticides and fertilizers in marijuana are the least of concern to one's health.  i've only read one very bad case (http://stopthedrugwar.org/reader_blogs/2008/apr/18/marijuana_lead_laced_pot_newest_)

[alearguello]

the active ingrediant in marijuana isnt only known to not cause cancer, but is commonly used to TREAT cancer patients, and there are even studies out saying that THC prevents some types of cancer from even developing, one being breast cancer. note: smoking isnt the only way to get THC into your system, thats a common misconception. theres edibles, sprays, lotions, lip balm, pills.. just about anything you can think of for those with a smoking condition. i see it as a very personal choice since marijuana affects people differently. in my experience, i've found that by smoking it, you're in immediate control over your dosage, and can regulate how much YOU need and/or want. no doctor can prescribe your dosage, they simply give the OK for you to medicate yourself.  

i choose an organic plant over lab constructed pills anyday; its also very rare you'll ever find pesticides or fertilizers in marijuana. and not only is the product itself almost always 100% organic, but the process in preparing it (whether its to smoke it or eat it) is completely natural as well.

it doesnt control my life, but its definitely had a positive effect. i'm very open-minded and so i feel almost anyone in the state of mind that marijuana is a medicine will benefit greatly from it, whether it be emotinally, physically, or mentally. and that just like everything else, even the foods we take in, it needs to be moderated according to YOU and how YOU feel. no modern day lab-made medicine can offer you that, just check out the damage "harmless" painkillers have caused in todays society. (and for the record, i am not speaking for potheads that just sit on their *** all day.)

it makes me think differently, it makes me focus, it relieves me of stress so that i can fall asleep on the nights that stress hits me hardest, it makes me question EVERYTHING, something people arent doing as much as they should these days. the way i see it, its all a big lie and a definite threat to our government who thrive off of the money they make by peoples addictions to painkillers and prescribed meds. it woke me up to issues that todays youth just let slide by so carelessly without realizing that the decisions they make now will affect how they will be living their lives for years to come, and i've never felt cleaner or more knowledgeable in my life. i'm only 20 years old.

i know i rambled off for a bit, but i hope this helped.
take care.