Lowering the legal blood-alcohol limit for driving also lowers the amount of teens will get behind the wheel after drinking, according to a new study.
In their study of drinking and driving behavior, University of Minnesota researchers found a 19 percent decrease in the frequency of teens who drove after any drinking in those states that lowered their blood-alcohol rates.
The investigators also found a 23 percent decline in the frequency of teenagers who drove after drinking at least five alcoholic beverages in those same states.
"The findings show that reducing blood-alcohol concentration limits is a potent tool to discourage driving after drinking behavior," said the study's lead author, Alexander Wagenaar, an epidemiologist at the University of Minnesota School of Public Health.
Laws Have ‘Sizable Effect’
Although these laws are not always rigorously enforced or widely publicized, Wagenaar says "the research shows that they are still having a sizable effect in preventing teenagers from drinking and driving."
The study, the largest survey of its kind, appears in the May issue of the American Journal of Public Health. The study evaluated the changes, if any, of the number of teens who drank and then drove after the blood-alcohol limit laws were lowered for minors. The authors compiled their data from a series of annual surveys of 5,000 high school seniors in 30 states.
Before 1983, no state had set a reduced alcohol limit targeted at minors. Between 1985 and 1992, a dozen states passed laws that lowered alcohol limits for minors only. In 1991, Congress passed legislation that gave the remaining states incentives to follow suit.
Laws There, But Not Always Enforced
A 1995 federal law was tougher, warning states they would lose a portion of their federal highway funds if they failed to enact a youth alcohol limit law. Today, all states have such youth laws, and many states are debating lowering the general limit for all drivers from 0.10 to 0.08.
Citing a study in Maryland, which recently lowered its legal limit for adult drunken driving from 0.10 to 0.08, the authors said a public information campaign more than doubled the effect of its youth drunken driving law.
"It's clear that these laws are having substantial effects even though they are only being partially implemented in many states," says Wagenaar. "These policies could be even more of a deterrent if they were more fully enforced."