i wouldn't be terribly concerned with health problems and weed unless you smoke everyday. even then, i bet something else will kill you first. if you smoke bongs and bowls all day, i bet you'd be fine. blunts and spliffs tho, i dunno.

either way, it's all about risk-reward. if you think it's too big of a risk and not enough reward, don't do it. i smoke because it brings me pleasure that is greater than any negative health effects (the few that there are) on me