My personal opinion on the topic is as follows:
I am only 20 yrs old but I have been smoking everyday for about 5 years and I am really not worried about my long term health for a couple of reasons. One is that the fact that if MJ has been considered a medicine since we have been walking this planet, I dont think that people would be dying left and right because of disorders or cancers caused from inhalation of Cannabis. Second, by myself I only smoke about a gram AT THE MOST a day so if you combine that with the fact that our lungs ROUTINLY clean themselves from tar I dont think the smoke is really adding up in my own situation. However if you smoke like 3 or 4 J's or blunts everyday for your entire life the smoke from the weed and the paper will probubly add up. Caughing up phlem, sore throat? Possibly. Cancer? I DOUGHT IT.

Tar does build up in your lungs unless vaporized; don't believe me? Then just take a glance at your pipe. However just like most "Fun" things that exist, ALWAYS USE IN MODERATION. If you wanna be safe and sure, just vape and/or edibles.

Happy Tokaging