Alcohol doesn’t cause permanent loss of IQ and is not carcinogenic. Also there are clear standards for driving under the influence of alcohol that cannot be so clear for marijuana.
If marijuana is so easy to obtain for teen agers, it is even easier for adults. So, what’s the big deal? I don’t know anyone who smokes marijuana that has any trouble getting it.
I know that the Gateway drug claim is controversial, but I’ll will give you an anecdotal story about it anyway. A friend of mine, who has a very laissez faire attitude toward drugs, talked about her drug experiences openly with her kids and even allowed them to, or at least didn’t stop them, smoking marijuana and drinking beer at home, as long as they didn’t drive afterwards. Her son started using other drugs and eventually became a heroin addict. He called her one time, when he was contemplating suicide, and told her that she was the worst mother in the world because she made drugs sound so harmless and like so much fun.
As a matter of fact I know two mothers, with similar attitudes and similar results. Both of the boys were top students before the marijuana use. One of them who had been in advanced classes and a soccer star, dropped out of high school. I don’t know what happened to the other.
Marijuana and IQ:
'“Scientifically, these are extremely preliminary findings,” cautions Carl Hart, associate professor of psychology at Columbia University, who has studied the cognitive effects of marijuana in humans in the lab and was not associated with the research. [...] There are also other factors — such as child abuse or other trauma — that might lead people to seek escape in heavy marijuana use and could also affect brain function. Meier and her colleagues did not examine these factors but say it’s possible that such elements could explain the results better than marijuana itself.' - http://healthland.time.com/2012/08/28/does-weekly-marijuana-use-by-teens-really-cause-a-drop-in-iq/
Alcohol:
"researchers confirmed previous findings that alcoholism is associated with thinking problems and lower IQ" - http://www.ur.umich.edu/0506/Oct17_05/15.shtml
"heavy drinking may have extensive and far–reaching effects on the brain, ranging from simple “slips” in memory to permanent and debilitating conditions that require lifetime custodial care." - http://pubs.niaaa.nih.gov/publications/aa63/aa63.htm
and is not carcinogenic.
"Alcohol is a known cause of cancers of the:
Mouth
Throat (pharynx)
Voice box (larynx)
Esophagus
Liver
Colon and rectum
Breast
"Alcohol may also increase the risk of cancer of the pancreas." - http://www.cancer.org/cancer/cancercauses/dietandphysicalactivity/alcohol-use-and-cancer
Also there are clear standards for driving under the influence of alcohol that cannot be so clear for marijuana.
Roadside sobriety tests can fill the gap until we get biochemical tests in place.
If marijuana is so easy to obtain for teen agers, it is even easier for adults. So, what’s the big deal?
The big deal is that keeping marijuana selling illegal hyperinflates its profits and channels those profits into criminal hands.
I know that the Gateway drug claim is controversial
The gateway claim is nonsense - research shows that the correlation between earlier marijuana use and later use of other drugs can be explained by a "common-factor" model, that is, a third factor that causes both results, such as individuals' opportunities and unique propensities to use drugs, or mor broadly a social or psychological predisposition towards anti-social behaviour. (http://www.rand.org/pubs/research_briefs/RB6010/index1.html, http://rds.homeoffice.gov.uk/rds/pdfs2/hors253.pdf)