[TheSutterDynasty]

Here's a review of some literature findings for you, Hoot.

Originally Posted by Abstract

There is evidence of psychiatric, respiratory, cardiovascular, and bone toxicity associated with chronic cannabis use. Cannabis has now been implicated in the etiology of many major long-term psychiatric conditions including depression, anxiety, psychosis, bipolar disorder, and an amotivational state. Respiratory conditions linked with cannabis include reduced lung density, lung cysts, and chronic bronchitis. Cannabis has been linked in a dose-dependent manner with elevated rates of myocardial infarction and cardiac arrythmias. It is known to affect bone metabolism and also has teratogenic effects on the developing brain following perinatal exposure. Cannabis has been linked to cancers at eight sites, including children after in utero maternal exposure, and multiple molecular pathways to oncogenesis exist.

Reece, A.S. Chronic Toxicology of Cannabis. Clinical Toxicology. 2009. 47: 517-524.

I'm not sure if you'll be able to acess it online. The author has gathered some of the literature with negative-oriented findings. Of course, there are also studies that haven't found such negative effects. At any rate:

...with a dose equivalent of one cannabis joint to 2.5-5 cigarettes

That's from Lange P. Cannabis and the lung. Thorax 2007; 62:1036–1037.