I am not going to argue that smoking anything is healthy for you, including marijuana, but the studies are consistently showing that despite having elevated amounts of tar and carcinogens there is a lowered instance of head/neck carcinomas and also lung cancer with marijuana users.
Your 2 articles that actually mention mj use and lung cancer was the same study of 79 patients with only a subset thereof being marijuana users, not a very large statistical sampling to be drawing definitive correlations.
Here are a few other studies to mull over:
fisrt this one, which was sponsored by the NIDA but after the results came in they decided against publishing it:
Study Finds No Link Between Marijuana Use And Lung Cancer
how could this be?? research is starting to find some interesting things, the following is but one of many other studies that are starting to come out pointing to cannabinoids and potential anti-carcinogenic properties:
Marijuana Cuts Lung Cancer Tumor Growth In Half, Study Shows
And while we are at it an abstract on a study of another common cancer with smokers:
A Population-Based Case-Control Study of Marijuana Use and Head and Neck Squamous Cell Carcinoma -- Liang et al. 2 (8): 759 -- Cancer Prevention Research
There are pulmonary issues as a result of marijuana smoking for sure, but the risk of developing cancers is significantly higher with cigarettes.
Either way both are moot, the Gov. has no business dictating what adults can and cannot do to their own bodies.