alcohol abuse and teenagers

What are the dangerous effects of alcohol use in teens?
Just a few of the many dangerous effects of alcohol use in teens include the following:
Alcohol decreases teens' ability to pay attention.
The younger a person is when they begin drinking, the more likely they are to develop a problem with alcohol.
Each year, almost 2000 people under the age of 21 years died in car crashes in which underage drinking is involved. Alcohol is involved in nearly half of all violent deaths involving teens.
More than three times the number of eighth-grade girls who drink heavily said they have attempted suicide compared to girls in that grade who do not drink.
Teens that drink are more likely to engage in sexual activity, have unprotected sex, or have sex with a stranger.
Excess alcohol use can cause or mask other emotional problems, like anxiety or depression.
Drinking in excess can lead to the use of other drugs, like marijuana, cocaine, or heroin.
http://www.medicinenet.com/alcohol_and_teens/article.htm

How can parents prevent alcohol use?
Clear communication by parents about the negative effects of alcohol, as well as about their expectations regarding drug use, have been found to significantly decrease alcohol use in teens. Adequate parental supervision has also been found to be a deterrent to alcohol use in youth. Alcohol, and other drug use, has been found to occur most often between the hours of 3 and 6 p.m., immediately after school and prior to parents' arrival at home from work. Teen participation in extracurricular activities has therefore been revealed to be an important measure in preventing use of alcohol in this age group. Parents can also help educate teens about appropriate coping and stress-management strategies. For example, 15- to 16-year-olds who use religion to cope with stress tend to use drugs significantly less often and have less problems as a result of drinking than their peers who do not use religion to cope.