Prof: Alcohol impairment goes beyond BAC number

May 21, 2013  

WEST LAFAYETTE, Ind. - Drivers may think they have the green light to drive when their blood alcohol levels fall below the legal limit or the buzz wears off, but that's not the case, says a Purdue University expert.

"It's more than just a number, and my advice is to not drink and drive at all because there really is no safe level," says Julia Chester, an associate professor of psychological sciences who studies genetic differences and sensitivity to alcohol effects. "Impairment means the driver's reflexes and attention are limited, and someone who's been drinking could be impaired by withdrawal effects or fatigue even if the level of alcohol in their blood is metabolized to a lower level. This is especially something to consider for people who have been drinking all day in hot weather during a summer holiday weekend party. The buzz may be gone, but the aftereffects of consuming so much alcohol could still hinder your ability to drive a car."

Chester says the blood alcohol content number provides a false sense of security because it's a snapshot of alcohol's effects. The current federally approved legal level, also known as BAC, is .08. Recently, the National Transportation Safety Board recommended that states lower the level to .05 in an effort to reduce traffic fatalities. 

"Each person and situation is different, and the question is to what degree will it impair you," Chester says. "Various individual considerations that relate to alcohol impairment include how much food someone has consumed, what medications have been taken and how rested is the driver. Genetics play a role, and an individuals' genetic and experiential history may make them more sensitive to alcohol's cognitive- and motor-impairing effects."

Writer: Amy Patterson Neubert, 765-494-9723,

Source: Julia Chester, 765-494-6863, 

Related website: 
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