That would pretty much have to be the answer to the lung argument.
Tobacco smokers can smoke up to 2 packs per day, or 40 cigaretts. Imagine 40 joints a day! That certainly would increase the risk of lung problems!
Tobacco is poison and cannot be injested without toxins, pot can and isn't poison.
Although I feel it should be a social thing, like having a drink, I vote for eating it.
My mom used to smoke 3 packs per day. Sweet as she is, she was a raging bitch when she kicked the habit. That's some serious withdrawal there.
No way could someone smoke that many cigs per day. I used to make a good joint last 2-3 days.