WASHINGTON — Drinking and driving by teenagers has declined by almost one-fifth in states with stricter alcohol laws, according to a 30-state survey of high school seniors.

The survey, appearing Tuesday in the American Journal of Public Health, shows that policies discouraging risky drinking can have an impact on young people, said Alexander C. Wagenaar of the University of Minnesota, first author of the study.

Wagenaar said the survey was done before all 50 states set the legal blood alcohol concentration level at 0.02 percent for drivers under 21. The effects should eventually be seen in every state, he said.

"Clearly it shows that the laws are working," Mothers Against Drunk Driving spokeswoman Wendy Hamilton said. "Teenagers are getting it."

There is a different threshold for adults, however. For at least 19 states and the District of Columbia, the legal limit for adults is now 0.08 percent. A federal law passed last year requires a 0.08 level in all states by 2004. States that fail to comply could lose federal highway funds.

Wagenaar said data from the new survey is consistent with other studies that have shown a 10 percent to 20 percent decline in alcohol-related car crashes in states with a 0.02 blood alcohol level for youthful drivers.

"The (blood alcohol level) law for young people reinforces the law that moved the legal drinking age up to 21," he said.

In the new study, researchers addressed a series of questions about drinking and driving to 5,000 high school seniors in 30 states. The annual survey is identical in method and questions to one that began in the late 1970s, said Wagenaar. As a result, he said, it accurately measures the effects over time of specific laws on the drinking and driving habits of young people.

The survey compared answers to the questions collected before the youth alcohol laws were passed, with answers from after the laws were passed. The dates of passage in each state varied, but the surveys were adjusted so that the time pattern was the same, he said.

The study found that after the BAC laws were passed, 19 percent fewer youthful drivers admitted that they had driven a car, truck or motorcycle after drinking any alcoholic beverage.

Asked if they had driven after five or more drinks, 23 percent fewer admitted that they had taken the wheel.

Wagenaar said teens also are showing they are more cautious about others drinking. He said the survey found that 7.1 percent fewer teens admitted riding with drivers who had been drinking, and 13.5 percent fewer said they had ridden with a driver who had consumed five or more drinks.

In a broader sense, said Wagenaar, the study shows that policies and laws that make alcohol less accessible and emphasize its possible risks are affecting a gradual shift in the perception of the role of drinking in society.

"Policies, such as raising the drinking age to 21 or tighter regulation on alcohol sales, help to engender a norm that alcohol is not the same as soda pop, that it can be a risky substance and that it is not without hazards," he said.

The American Journal of Public Health is a monthly publication of the American Public Health Association.

Web site: www.apha.org