1) I'll have to take a rain check on a more detailed response-- I can't check most journals for reviews from home, and I won't be in my office again until next Friday on account of business travel. I'm speaking off the cuff.

2) My general impression is that there isn't a complete consensus, largely because the government simply doesn't allow most studies which would give the most useful data on humans. The fact that you aren't even allowed to effectively ask the question has definitely ruffled feathers in the scientific community, and I recall reading some angry editorials to that effect in either Science or Nature.

3) Animal models are less useful here. It's relatively easy to pump rats/etc. full of tobacco smoke and count tumors. Quantifying neurological effects involves a lot more indirect interpretation, and generally speaking you'll need a lot more experimentation to come to firm answers. (Which leads us back to #2.)

3B) Obviously, a lot of humans are experimenting with the drug, but they're experimenting with material that is produced in smaller batches and is of highly uneven composition, dosage, etc. Plus, it's not simple to set up trials where you interview pot smokers because of the fear of legal repercussions.

4) In terms of respiratory problems, it's similar to smoking similar amounts of tobacco-- inhaled burning plant being more or less equal to inhaled burning plant. Obviously, pot smokers tend to smoke much smaller quantities in terms of mass, so the effects aren't quite as bad as you'd typically see with tobacco, but only because of dosage. I think even a lot of the pro-pot crowd admits the drug would probably be safer if other deliveries were tested, as smoking marijuana is definitely linked to respiratory illnesses.

5) I've never seen a reputable source claim it was harmless to the brain, but the pertinent unknown is how it stacks up against legal drugs, notably alcohol and tobacco, but also way-too-commonly-prescribed stuff like Ritalin and Prozac. (Some people claim pot is kept illegal in part because Big Pharma dreads more competition, but it's clear to me that they'd make a lot more money if marijuana was legal and they could make it.) It's an anomaly that your doctor can't prescribe smoked marijuana for medical purposes, given that they have more potent things with more potent side effects in their cabinet (opiates, etc.). Ironically, the best justification for this is that the drug's full medical effects aren't completely understood... because it's too hard to legally do formal trials... which leads us back to #2.

valguarnera@carrionfields.com