If you wait until your children are in middle school to talk to them about the dangers of alcohol, you may be too late.

That's the message being echoed this fall by educators and substance-abuse experts in the wake of a study released at the start of the school year in which 7 percent of fourth-graders said they've had an alcoholic drink in the past year.

Ten percent had more than a sip of alcohol in that time period, according to the study authored by John Donovan, an associate professor of psychiatry and epidemiology at the University of Pittsburgh Medical Center. It was published in the September issue of "Prevention Science".

The largest jump in underage alcohol use happens between fifth and sixth grade, when many children begin middle school, the researchers concluded after conducting a review of national and statewide surveys.

"There is a fairly sizable amount of literature showing that the earlier people start to drink, or even have their first drink, the more likely they are to have problems later in life with alcohol, drugs, delinquency, risky sexual behavior (and) motor vehicle accidents," Donovan says.

"Alcohol is the drug of choice for children," says Mary Easley, the first lady of North Carolina and co-chair of the Leadership to Keep Children Alcohol Free, a coalition of governors' spouses working with public and private agencies.

"Peer pressure plays a role, but strong parental involvement early on can counteract it," she says.

Parents must be aware, Easley says, of the serious consequences children may face if they start drinking at a young age.

"Parents look at their kids and think they physically look like miniature adults, but developmentally they are not," says Steve Pasierb, president of the Partnership for a Drug-Free America. "Any kind of substance abuse through the teenage years can really set a child up for lagging development."

Once in middle school, children's attitudes toward alcohol shift dramatically, says Joseph Califano, head of the National Center on Addiction and Substance Abuse at Columbia University and former secretary of the Department of Health, Education and Welfare.

In elementary school, most children see drinking alcohol as wrong, Califano says. But in middle school, the presence of older children can be very influential.

There is no shortage of substance education in classrooms across the country. In fact, 37 states require drug and alcohol education, although the timing and content of the classes vary, according to Join Together, a program at the Boston University School of Public Health, which fosters community-based alcohol and drug abuse prevention and treatment programs.

One federally funded program now being developed by the American Association for the Advancement of Science will target middle school students nationwide and take a science-based approach to teaching how alcohol physically harms the body.

A recent report by Join Together states that schools should not be the main provider of prevention education because teachers do not have the resources, time or training to be effective.

Schools are relied upon "by default," Join Together director David Rosenbloom said in a prepared statement. But "schools are only part of the community solution."

Califano agrees. "Parents should be talking to their kids when they ask questions and should be ready to answer honestly," he says. "And believe me, they'll ask in first, second and third grade."

Donovan noted in his study that some of the younger children who reported drinking alcohol were probably served by their parents. While a glass of wine or a sip of beer at home may seem harmless, Donovan warns that alcohol introduction in what is perceived as a safe family context will not necessarily lower a child's risk of abusing alcohol later in life.

Parents should recognize that all kids are at risk, experts say.

"Don't think that because you're not a drinker or you think your kid lives in a good neighborhood that they won't drink," Pasierb says. "You need to weigh in anyway, and you need to have that conversation that a no-alcohol-use standard exists."