http://www.ncbi.nlm.nih.gov/pubmed/19638490
http://jpet.aspetjournals.org/cgi/reprint/jpet.106.105247v1
Some empirical research on cannabinoids and cancers. Just do a google scholar/pubmed search for more.
It's illogical to assume that marijuana causes cancer. No case of lung cancer resulting from marijuana use alone has ever been documented.
In addition to this, THC is a bronchial dilator, which means it works like a cough drop and opens up your lungs, which aids clearance of smoke and dirt. Hence, coughing and phlegm.
Since 1982, UCLA researchers have evaluated pulmonary function and bronchial cell characteristics in marijuana-only smokers, tobacco-only smokers, smokers of both, and non-smokers. Although they have found changes in marijuana-only smokers, the changes are much less pronounced than those found in tobacco smokers.
The nature of the marijuana-induced changes were also different, occurring primarily in the lung's large airways - not the small peripheral airways affected by tobacco smoke. Since it is small-airway inflammation that causes chronic bronchitis and emphysema, marijuana smokers may not develop these diseases
- Tashkin, D.P. et al, "Longitudinal Changes in Respiratory Symptoms and Lung Function in Non-smokers, Tobacco Smokers, and Heavy, Habitual Smokers of Marijuana With or Without Tobacco," pp 25-36 in G. Chesher et al (eds), Marijuana: an International Research Report, Canberra: Australian Government Publishing Service (1988).
As for dependence:
Marijuana produces no withdrawal symptoms no matter how heavy it is used. It is habit forming (psychologically addictive), but not physically addictive. The majority of people who quit marijuana don't even have to think twice about it. Comparing marijuana to addictive drugs is really quite silly.
For a drug to be physically addictive, it must be reinforcing, produce withdrawal symptoms, and produce tolerance. Marijuana is reinforcing, because it feels good, but it does not do the other two things. Caffeine, nicotine and alcohol are all physically addictive. -
- abovetheignorance.com
Also backed up by
http://www.marijuanalibrary.org/Exposing_09_1095.html (Exposing Marijuana Myths: A Review of the Scientific Evidence by Lynn Zimmer, Associate Professor of Sociology, Queens College and John P. Morgan, Professor of Pharmacology, City University of New York Medical School)
on amotivational syndrome:
http://www.marijuanalibrary.org/Exposing_11_1095.html
The lowered sex drive thing is just laughable. And that paper by Zimmer and Morgan also has this to say on the subject of marijuana causing learning difficulties when you're not high.
The original basis of this claim was a report that, upon postmortem examinations, structural changes in several brain regions were found in two rhesus monkeys exposed to THC. 51 Because these changes primarily involved the hippocampus, a cortical brain region known to play an important role in learning and memory, this finding suggested possible negative consequences for human marijuana users.
Additional studies, employing rodents, reported similar brain changes.
However, to achieve these results, massive doses of THC - up to 200 times the psychoactive dose in humans - had to be given . In fact, studies employing 100 times the human dose have failed to reveal any damage. 52
In the most recently published study, rhesus monkeys were exposed through face-mask inhalation to the smoke equivalent of four to five joints per day for one year. When sacrificed seven months later, there was no observed alteration of hippocampal architecture, cell size, cell number, or synaptic configuration. The authors conclude:
"while behavioral and neuroendocrinal effects are observed during marijuana smoke exposure in the monkey, residual neuropathological and neurochemical effects of marijuana exposure were not observed seven months after the year-long marijuana smoke regimen." 53
Thus, 20 years after the first report of brain damage in two marijuana-exposed monkeys, the claim of damage to brain cells has been effectively disproven.
Interestingly, according to a
2001 study published in the journal Archives of General Psychiatry, long-term cannabis smokers who abstained from pot for one week “showed virtually no significant differences from control subjects (those who had smoked marijuana less than 50 times in their lives) on a battery of 10 neuropsychological tests.” Investigators added, “Former heavy users, who had consumed little or no cannabis in the three months before testing, [also] showed no significant differences from control subjects on any of these tests on any of the testing days.”
This
study also concludes that the impact of cannabis on the brain is minimal.
