How much alcohol does it take to get intoxicated?Many people figure a few beers at a ballgame or a couple of glasses of wine with dinner won’t put them over the legal limit for driving. But how alcohol affects people is highly individual, with a number of factors in the mix. Quick shots of liquor hit the bloodstream faster than slow sips of wine. Drinking on an empty stomach impairs reflexes more than consuming alcohol with food. And women and older drinkers generally hit legal intoxication levels sooner than men and younger people. Carbonated beverages raise alcohol levels faster, because the gas irritates the stomach lining, causing alcohol to be absorbed faster. (Sweet or caffeinated alcoholic drinks aren’t absorbed any faster, it just seems that way because people often consume more of them than they realize.)
And factors like fatigue, stress, illness and depression can magnify alcohol’s impact.Eileen Wolter was driving home from an office Christmas party she had organized in Los Angeles in 1998. “I was definitely under a lot of stress,” she says. She had had several mixed drinks, a few glasses of wine and very little food, but thought she was fineuntil she took a turn too fast and hit a stop sign. She was driving with a flat tire and a broken wheel, causing even more car damage. A police car stopped to see if she was OK, and she flunked a breathalyzer test. “I blew a .09,” says Ms. Wolter, who was arrested, fined $2,000 and sentenced to community service and alcohol education classes. “I wasn’t hurtjust humiliated and angry and scared. Dealing with all of itand the fact that I could have hurt myself or someone elsemade me realize what a stupid chance I’d taken,” says Ms. Wolter, now a 40-year-old writer and mother of two who says she will never drink that way and drive again. Drinkers who think they can tell when they’ve had enough are very often wrong. “Alcohol can affect your reflexes even if you feel fine,” says Samir Zakhari, director of the division of metabolism and health effects at the National Institute of Alcohol Abuse and Alcoholism. That’s a key reason why many experts urge people who plan to drink any amount of alcohol not to drive, and vice versa.
From a $5 keychain gizmo to a $2,000 desktop device, dozens of blood-alcohol testers are on the market today, allowing consumers to test themselves, their guestseven their wayward teenagers. Most work in the same way: You wait as a digital counter counts down, then inhale deeply and blow into a plastic mouthpiece or across a small hole. The devices don’t directly measure blood-alcohol concentration (BAC), but a derivative in breath. They convert it to BAC and display it on a digital screen, sometimes adding ‘caution’ or ‘danger. We tested three models at our BAC party and found that in general, the smaller the device, the higher the readingnot necessarily a bad thing, we decided. But they were all within a hundredth of a percentage point, whether it was the BreakKey, a $69 keychain model weighing less than an ounce, the AlcoHAWK Slim Digital Alcohol Breath Tester ($55), or the BACtrack Select S80 Breathalyzer ($249) that had a readout to an extra digitworth it to the guest who wracked up a .079% score, just shy of the .08% limit. (The $5 Wingman Sport Breathalyzer, which arrived after the party, gave a consistently higher reading compared with the others in a second test .190 after a single glass of wine, while the BACtrack and the AlcoHAWK both read .04. The BreakKey had mysteriously stopped functioning and kept reading “Blow… Hard.” Results can be thrown off by vigorous exercise, medical conditions like acid reflux and diabeteseven dieting, which can raise the level of acetones in a person’s breath that some devices falsely read as alcohol. Mouthwashes that contain alcohol can also make readings high, although manufacturers say that newer breathalyzers that use fuel-cell technology don’t give as many false-positive readings as those made with semiconductors. Most police departments use fuel-cell models for preliminary readings in the field and tabletop versions at the station that are accurate enough to use in court. Police breathalyzers must also be approved by the National Highway Transportation Safety Administration, while consumers models sold in the U.S. need clearance from the Food and Drug Administration.Many of the devices urge consumers to keep them in their cars or their purses to test themselves before getting behind the wheel. But many experts and advocacy groups worry that they can give people a false sense of complacency. Samir Fakhari, director of the division of metabolism at the National Institute of Alcohol Abuse and Alcoholism, says that home breathalyzers may be reasonably accurate in giving ‘an approximation of your BAC.’ But he worries that they can be misused, misinterpreted and even befuddle someone who is truly inebriated. ‘It’s a better idea not to drink at all if you’re driving,’ he says.
If used too soon after a person has imbibed, many breathalyzers will inadvertently measure the vapor left in the mouth rather than the level derived from blood, which is why most models advise users not to test for least 20 minutes after drinking or eating to get an accurate reading.