Today's teens cannot escape exposure to alcohol, drugs and sex. They would be much better served if they could learn the truth about these things from adults instead of being encouraged by laws and attitudes to hide from them.

We Americans have lively disagreements about lots of things, but when it comes to kids, booze and drugs, our rich civic conversation turns anemic. We scrunch our faces into a middle-aged scowl, wag our fingers at the youngsters and say ``don't go near that stuff.''


Then we pour ourselves an adult refreshment.


That's why it's good to hear from John M. McCardell, a retired college president who is not afraid to challenge conventional wisdom.


``Consider this,'' McCardell told the Daily News. ``Alcohol education is now mandated only after you've been convicted of DUI. What genius thought that one up? You get convicted and then you have to take alcohol education?


``We're spending a lot of money and a lot of man-hours too late.''


McCardell knows something about education and about underage drinking. As the retired president of Middlebury College, he knows that if parents and teachers don't teach young people about drinking, their buddies at the frat house will.


Parents can teach kids about the pleasures of moderation, the distinctions between wines, and how to use alcohol as a stress-reducer and social lubricant.


The buddies at the frat house will teach them that drinking isn't about taste or sociability, it's about getting hammered. They will teach drinking games designed to get as many kids as drunk as possible. They will show them how to use a funnel and tube to put large quantities of beer into the stomach without having to bother with swallowing.


Which lessons would you rather your children learn?


But try to teach your kids and their friends how to drink responsibly, and you can find yourself in jail. The campus bars that once provided a setting for mature, supervised drinking have all been closed down. Young people are drinking as much as ever, but laws and policies force them to do it in places where no adult can go.


``Zero tolerance'' policies at colleges often backfire. Students caught drinking in the dorms are forced to move off-campus for a semester - to apartments where students can, and do, drink all they want.


McCardell's solution cuts against the prohibitionist grain that has run through alcohol and drug policies for 30 years. He says we should lower the drinking age to 18, but treat it like driving. At 18, young people could legally drink at home with their parents. After they graduated from high school, they could apply for a state ``drinking license'' once they had completed an alcohol education course.


Unlike too much of what passes for drug education, such a course should be built on facts, not propaganda. It should cover practical knowledge, stressing the difference between drug use and drug abuse, instead of ``just say no.''


Drug education should incorporate what science has learned about the neurochemistry of addiction, much of which goes against the conventional wisdom. Addiction is ``a disease of the brain,'' not a character flaw, Dr. Nora Volkow, director of the National Institute on Drug Abuse, told the nation's leading drug researchers at their annual meeting this week. Addiction has a genetic component - if your parents are alcoholics, you will likely have the same tendency - but is triggered as well by early experiences.


Researchers say the earlier young people start drinking or using drugs, especially binge drinking or heavy drug use, the greater the tendency toward addiction. They also debunk the myth that alcohol abuse is less prevalent in Europe, where even children drink wine with dinner and the drinking age is lower. Binge drinking among teenagers in Britain, France and Germany is a bigger problem than in the U.S.


That doesn't necessarily argue against McCardell's initiative, which he is promoting through an organization named ``Choose Responsibility.'' Allowing moderate drinking by 18- to 21-year-olds would likely be less damaging to young people than the unsupervised binge drinking that is now the norm. But the research reinforces the importance of keeping alcohol away from children younger than 18.


The brain isn't fully developed until age 23, neuroscientists have learned, which explains a lot about our children's behavior. While their brains are still developing, they are more easily damaged by drug abuse. Aaron White, who studies adolescent alcohol use at Duke University Medical Center, challenges another bit of conventional wisdom while arguing against lowering the drinking age:


``If you're going to do that, I suggest you teach them to roll joints,'' he told Newsweek, ``because the science is clear that alcohol is more dangerous than marijuana.''


Indeed. Cannabis is less addictive than alcohol, and less damaging to your body. A lethal dose of alcohol is 10 times its effective dose - one way scientists measure a drug's dangerousness - but there is no known lethal dose of marijuana.


McCardell may be a lonely voice advocating for a more realistic approach to teens and drinking, but at least he has a voice. America has an estimated 25 million marijuana users, but no respected voice has emerged to argue in favor of regulated cannabis, sold in liquor stores and used moderately by responsible adults.


I'm sure there are educators doing their best to teach fact-based drug and alcohol courses in some school health classes, including lessons in peer pressure, self-esteem and mental health, which are all critical pieces of the substance abuse puzzle. There are surely sex education teachers who go beyond abstinence and birth control to cover other aspects of sex that are equally important, such as intimacy, abusive relationships, gender identity, body image and sex in the media.


But those who would teach young people what they really need to know about sex and drugs are hampered by laws, politics and culture that confuse telling the truth with ``sending a message.'' Children need sermons, to be sure, but slogans that pretend that maturity and understanding arrive magically on your 21st birthday do more harm than good.


Today's teens cannot escape exposure to alcohol, drugs and sex. They would be much better served if they could learn the truth about these things from adults instead of being encouraged by laws and attitudes to hide from them.


Rick Holmes is opinion editor for the MetroWest Daily News. He can be reached at rholmes@cnc.com.