Dear Dr. Ken: I'm still living with my roommate from college. Thing is, he wakes 'n' bakes almost every day (getting stoned first thing in the morning). I've tried to convince him he should take it easy, but he says I'm just dropping "propaganda."

Aside from all the Doritos and Mountain Dew, will smoking so much mess with his health? -- Barry P., Austin, Texas

Barry: Sorry to be a buzzkill, but smoking pot affects your short- and long-term health. You expect the impaired cognitive function (messed up thoughts), stunted psycho-motor skills (lack of coordination) and sedation (chilling). Yet the long-term effects of regular pot smoking will really harsh your mellow.

Here's a list of possible chronic effects of the chronic:

Breathing: Lung problems can be pronounced with regular smoking. It's been said three to four joints a day result in breathing problems that are comparable to a pack-a-day cigarette habit.

Sperm and "Man Boobs": Marijuana use impairs sperm and lowers testosterone levels, which can lead to impotence, loss of interest in sex, and gynecomastia, aka "man boobs."

More effects (after the jump)

Cancer: Marijuana, like tobacco, produces a host of known carcinogens and toxic compounds when burned -- whether in a joint, feathered roach clip or skull bong. Frequent pot smokers tend to have more pre-cancerous lung lesions, which often become cancer sooner or later. That risk depends on the frequency and intensity of use.

Gums: A recent study found pot smokers are more likely to get gum disease.

Mental Illness: Chronic use of marijuana (smoked, eaten or in pill form) is associated with an increased risk of schizophrenia, though not necessarily caused by it. Studies of regular marijuana use in relation to the development of depression, impaired memory, or impaired thought have shown mixed results.

Dependence: After long-term use, there can be physical and mental dependence. The body can take a month to adjust to life without pot.

There are, of course, a number of approved medical uses for marijuana and its active ingredient, THC, but chances are you're not looking to your doctor for a prescription. The biggest health risk from smoking pot once or twice is an accidental injury. Otherwise, it's not likely to result in a major health problem. Increased use, however, leads to increased risk.

Dr. Ken Spaeth is a physician and Research Fellow at the Harvard School of Public Health. He is also co-author of the Bioterrorism Sourcebook. You can e-mail him your questions at askdrken@aol.com.