Pot Kills (very rarely)
I've been talking with spiritualmonkey in the comments of another post about medical marijuana and whether to encourage or require medical cannabis dispensaries to treat their "medication" like other medication: to standardize it, dispense it in measured doses, or certify its purity and potency through trusted third parties. He pointed out (I hope I'm paraphrasing his argument correctly) that while this ought to be true of potentially toxic, commerically synthesized medications where overdose is a concern, THC is a naturally occurring agent with an extremely low toxicity . Cannabis has never killed a single person in centuries of recreational and medicinal use. It is unnecessary to demand testing for purity and potency for such a safe and harmless medication.
I've done a bit of checking and it turns out that there are a few documented cases of medical marijuana causing death in medical patients. Immunocompromised AIDS patients die from opportunistic infections introduced by contaminated marijuana. Fatal aspergillosis is associated with smoking contaminated marijuana in a marrow transplant recipient. Pulmonary aspergillosis is caused by inhalation of contaminated marijuana smoke. Hash oil caused exogenous lipid pneumonia which killed a kidney transplant patient. THC overdose isn't killing patients, but contaminants in the plants are. Natural contaminants. As askesis explained in a regrettably deleted post "natural" doesn't mean "safe". Many of the most toxic substances in the world are "natural" because natural things are trying to kill you every day.
Beyond these confirmed kills there seem to be a few cautionary signs. Cannabinoids seem to cause "neuron death", "a perpetuating role in liver damage", "interfering with peritoneal macrophage function", or be "a trigger for myocardial infarction" (2,3) or hypertension. There are potential negative complications for schizophrenic patients. It's been weakly linked to SIDS. Even healthy recreational users are concerned about glyphosate or parquat contamination (2) and the same fungal contamination mentioned above. (Koro Syndrome, "a transient state of acute anxiety characterized by the triad of a deep-seated fear of penile shrinkage, its disappearance into the abdomen, and apprehension regarding inevitable impotence or even death", is included not because it is a health risk but because it is totally hilarious. The death of a cannabis bodypacker due to perforation of the rectum doesn't count either.)
This isn't to say that cannabis is simply a minefield of danger with no reward. Cannabinoid chemicals are apparently involved in "apotosis" a cell's decision whether to die and might help encouraging cancer cells to die and are neuroprotective antioxidants which might be why it's being considered as a treatment for brain tumors. And these benefits aside, nearly every medication can have bad interactions or unwelcome side effects. Side effects don't mean a medication isn't worth considering.
None of this should come as a surprise to anyone. Patients are not healthy by definition. Sick people don't have the same tolerance to contaminants, resistance to diseases, and ability to bounce back that healthy people do. Immunocompromised patients, or patients with kidney or liver damage, or patients with weak hearts could have serious problems processing contaminated medicines, even if those contaminants are "natural". Just because a chemical is naturally occurring and relatively nontoxic doesn't give a caregiver carte blanche to use it in any form, strength, or state of purity, or delivery method to treat any disease or relieve any symptoms. Illness is a reason to be more cautious and remove as many unknown variables as possible which might otherwise complicate treatment. I'm OK with using cannabis medically and I'm OK with using cannabis recreationally, but I'm not cool with using a recreational product for medical purposes - you wouldn't choose steak knives or needle and thread for an operation when sterile scalpels and sutures were available. When something is used for medicinal purposes it needs more precision, more regulation, more testing, and more scrutiny than the equivalent recreational substance. Anyone who tries to say otherwise is smoking something.
I've done a bit of checking and it turns out that there are a few documented cases of medical marijuana causing death in medical patients. Immunocompromised AIDS patients die from opportunistic infections introduced by contaminated marijuana. Fatal aspergillosis is associated with smoking contaminated marijuana in a marrow transplant recipient. Pulmonary aspergillosis is caused by inhalation of contaminated marijuana smoke. Hash oil caused exogenous lipid pneumonia which killed a kidney transplant patient. THC overdose isn't killing patients, but contaminants in the plants are. Natural contaminants. As askesis explained in a regrettably deleted post "natural" doesn't mean "safe". Many of the most toxic substances in the world are "natural" because natural things are trying to kill you every day.
Beyond these confirmed kills there seem to be a few cautionary signs. Cannabinoids seem to cause "neuron death", "a perpetuating role in liver damage", "interfering with peritoneal macrophage function", or be "a trigger for myocardial infarction" (2,3) or hypertension. There are potential negative complications for schizophrenic patients. It's been weakly linked to SIDS. Even healthy recreational users are concerned about glyphosate or parquat contamination (2) and the same fungal contamination mentioned above. (Koro Syndrome, "a transient state of acute anxiety characterized by the triad of a deep-seated fear of penile shrinkage, its disappearance into the abdomen, and apprehension regarding inevitable impotence or even death", is included not because it is a health risk but because it is totally hilarious. The death of a cannabis bodypacker due to perforation of the rectum doesn't count either.)
This isn't to say that cannabis is simply a minefield of danger with no reward. Cannabinoid chemicals are apparently involved in "apotosis" a cell's decision whether to die and might help encouraging cancer cells to die and are neuroprotective antioxidants which might be why it's being considered as a treatment for brain tumors. And these benefits aside, nearly every medication can have bad interactions or unwelcome side effects. Side effects don't mean a medication isn't worth considering.
None of this should come as a surprise to anyone. Patients are not healthy by definition. Sick people don't have the same tolerance to contaminants, resistance to diseases, and ability to bounce back that healthy people do. Immunocompromised patients, or patients with kidney or liver damage, or patients with weak hearts could have serious problems processing contaminated medicines, even if those contaminants are "natural". Just because a chemical is naturally occurring and relatively nontoxic doesn't give a caregiver carte blanche to use it in any form, strength, or state of purity, or delivery method to treat any disease or relieve any symptoms. Illness is a reason to be more cautious and remove as many unknown variables as possible which might otherwise complicate treatment. I'm OK with using cannabis medically and I'm OK with using cannabis recreationally, but I'm not cool with using a recreational product for medical purposes - you wouldn't choose steak knives or needle and thread for an operation when sterile scalpels and sutures were available. When something is used for medicinal purposes it needs more precision, more regulation, more testing, and more scrutiny than the equivalent recreational substance. Anyone who tries to say otherwise is smoking something.