Health Risk of Marihuana Use

4.0: CONCLUSIONS

Reviews that do show health risks of marijuana are typically based on
poorly designed research, e.g., using massive doses of THC, far more
than even those levels consumed by the heaviest marijuana smokers.
Every study showing health risks has been discredited or refuted;
cannot be replicated; or has been shown to be in error by a majority
of studies on a given topic.

Apart from potential dangers from non THC factors in marijuana smoke,
the best research shows clearly that there are no substantiated
health risks associated with marijuana use. Indeed, there may well
be health benefits (in addition to the proven benefits of medical
marijuana), as marijuana levels of THC seem to strengthen the immune
system.

Laws prohibiting marijuana on the basis of health risks cannot be
justified by the research literature.

http://cannabisdigest.ca/health-risks-marijuana-use-james-geiwitz-ph-d/