But theres also the factor that people who tend to do marijuana are younger, and younger people can better resist health problems.

So even if someone did tons of weed in high school, the effects might not come until they are older. As people get older though and have families, they tend to get off the weed. Whereas smoking is just viewed as acceptable at any age.

I am no scientist but there are a huge number of factors to look at.

At the end of the day, they are both very bad for your health. The question is, should one be illegal and one not illegal. If marijuana is really that bad for your health, its not hard for insurance companies to just start making those folks who do marijuana pay more for the potential health problems they will have. The free market will fix it if it was legal.

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"The person who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself. " — John Stuart Mill