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Do you know your alcohol limit?
Many factors influence how many drinks it takes to reach legal driving limit of 0.08
The Times’ Shannon Casas, left, Sarah Mueller, and R. Keith Hatchell pass the time playing cards while they partake in alcoholic beverages at the Hall County Sheriff’s Office Training Center as they prepare for taking DUI field tests Tuesday afternoon.

See how the test subjects reacted in today's print edition of The Times.

Pushing the limit

The National Transportation Safety Board, an independent federal agency, recommended in May to lower the blood alcohol concentration to 0.05 from 0.08.

It was a little more than a decade ago that Georgia lowered its driving standard to 0.08 from 0.10, when legislation signed by President Bill Clinton in 2000 would have cut a portion of federal highway funds to states that did not comply with a legal limit of 0.08 or lower.

The 0.05 recommendation is likely to play out in a similar fashion, with a recommendation that the federal government authorize the National Highway Traffic Safety Administration to support states that adopt the recommendation by awarding “incentive grants.”

The odds: Drivers at a blood alcohol level of 0.05 are 1.38 times more likely to be in a crash than are sober drivers.

The consequences: The risk of fatal crash involvement at BACs between 0.05 and 0.079 ranges from about 3 to 17 times greater, depending on the age of the driver and the type of fatal crash (single-vehicle versus all crashes).

Outside lobbying groups: The American Medical Association since 2009 has called for a BAC of 0.04, saying that alcohol has a “wide variation of effect from subject to subject.”

International law: According to the International Center for Alcohol Policies and the World Health Organization, more than 100 countries have established maximum BAC limits at or below 0.05, including 25 of the 27 European Union members.

Deterrent effect: The majority of alcohol-impaired drivers in fatal crashes have BAC levels well over 0.08, the NTSB noted, but research on the effectiveness of laws limiting BAC levels has found that lowering the BAC limit changes the behavior of drivers at all BAC levels. Thus, reducing the BAC limit could have a broad deterrent effect, reducing the risk of injuries and fatalities.

Source: “Reaching Zero: Actions to Eliminate Alcohol-Impaired Driving,” published by the NTSB

The magic number for drinkers is 0.08. Past that and, if you’re caught driving, your next stop will be a jail cell.

But how do you determine when your body has hit that blood alcohol concentration? And as the National Transportation Safety Board pushes for that number to be lowered to 0.05, does it become even harder to determine when one drink is one too many?

In light of that recent recommendation, three Times staff members headed to the Hall County Sheriff’s Office Training Center to determine just how many drinks would put them over the limit.

Sgt. Jeff Shoemaker with the Hall County Sheriff’s Office guided the 3½-hour exercise, which prescribed exact amounts of liquor, tested participants with field sobriety tests and an Alco-Sensor breath test and ensured no one drove to or from the facility.

“I hope to learn something about myself. What kind of a drinker am I, and how much alcohol is OK?” government reporter Sarah Mueller said before the experiment.

Anatomy of drinking

How much alcohol is OK depends on a number of factors, one in particular being size. A larger person with a larger blood volume would see less effect per drink on their alcohol content, said Dr. Frank McDonald, a neurologist at The Longstreet Clinic in Gainesville.

The Times’ participants ranged in weight from 107 to 172 pounds.

After one margarita each, which contained 2 ounces of tequila, the science proved true.

Metro editor Shannon Casas was already at 0.06, past the new 0.05 recommendation. Mueller, was at 0.04 and presentation editor R. Keith Hatchell, the heaviest, at 0.02.

After a second drink with 1 ounce of tequila, Casas was just past 0.08 and Mueller was at 0.06. Hatchell had 2 ounces in his second drink and also was at 0.06. After a third drink with 2 ounces, Hatchell was at 0.08 and Mueller at 0.13.

But while the test subjects had clear, measured doses of how much they were drinking, drinkers at bars and restaurants may not.

“Realistically, how much alcohol is in your drink depends on how much your bartender likes you,” Shoemaker said.

Gender also plays a role in how the body processes the drinks, though.

Alcohol gets into the tissues and organs because, chemically, it goes where the body has water: the brain, the liver and muscle tissue, according to a presentation given during the exercise. The average male is 68 percent water, the average female only 55 percent. Thus a woman does not need as much alcohol to become intoxicated.

A person’s blood alcohol content over time is also determined by the contents of his or her stomach, Shoemaker said; 20 percent of alcohol is absorbed through the stomach walls, and 80 percent through the intestines.

The day’s subjects were specifically told to come on empty stomachs so they would get intoxicated more quickly.

The type of drink matters as well, with a 1½ -ounce shot of 80 proof distilled spirits equal to one 4-ounce glass of wine or one 12-ounce beer.

But one thing is the same for everyone: Only time can help you sober up, not substances like coffee or energy drinks.

“Yes, caffeine is a central nervous system stimulant, but that’s kind of an old wives’ tale,” McDonald said of efforts to sober up. “The only thing that helps is time, as the liver metabolizes the alcohol.”

The average person’s BAC drops by 0.015 per hour, Shoemaker said.

Slow it down

Moderate drinking — unless one is pregnant or has other medical risk factors — isn’t by itself a health risk, McDonald said. In fact he said some drinking can even reduce the risk of stroke.

“Alcohol per se is not necessarily bad. In fact, people who are moderate drinkers have a reduced risk of stroke than teetotaler or heavy drinkers,” he said, adding “By moderate, I mean one to two drinks daily.”

But drinking in any amount, when factoring in a 2-ton vehicle, makes driving a health risk, McDonald said.

Why? Because it slows you down.

“Alcohol affects the brain because it’s a central nervous system depressant and decreases brain function, which can interfere with coordination and response time,” he said.

Shoemaker compared drinking and driving, even at lower levels, to any other condition that increases roadway dangers.

“It’s like if it’s raining. You have to back off your speed a little bit — it’s just not safe for the conditions that are present,” he said. “Alcohol slows down the actions and reactions of the body. When we get to operating the vehicle, we’re multi-tasking, making judgments constantly. I probably won’t fail to act, but my reaction time is increased. And if it’s increased in a vehicle, then that’s that much further that we traveled.”

As blood alcohol concentration increases, the central nervous system becomes more depressed, and the effects are more pronounced.

“As it increases, coordination becomes extremely poor; your judgement gets worse, one’s ability to concentrate,” McDonald said.

One field sobriety test that measures that slow down asks the alleged drinker to stand on one foot and count to 30 in 30 seconds.

By the end of the exercise, and after three margaritas with 5 ounces of tequila, Mueller tried the test and counted only to 16.

Getting in a car with that slowed internal clock can lead to serious consequences.

About half of all fatal crashes involve drunken drivers, National Highway Traffic Safety Administration studies show. The average DUI driver admits to driving under the influence about 80 times each year, once every four or five nights.

The sheriff’s office reported more than 350 DUI arrests in Hall County in 2012.

The NTSB made its recommendation in May to lower the blood alcohol content level to 0.05 based on national traffic accident data.

Time to pull over

Shoemaker said deputies look for irregularities in drivers — driving too fast, driving too slow, braking erratically, drifting and swerving tend to be good indicators of driving under the influence.

Once pulled over, there are three key tests to determine sobriety.

There’s the horizontal eye test to detect “nystagmus,” an involuntary jerk of the eye caused by alcohol an other depressants. There also the walk a straight line test, and the one-leg stand test,” which measure both the test taker’s physical ability and ability to follow directions.

Often, the nystagmus test, because it’s an involuntary physical symptom of inebriation, can be most important for catching an intoxicated person who doesn’t seem impaired to the untrained eye.

“We’re looking to see the eye jerking pretty good — distinct, sustained nystagmus,” he said, explaining the eye moves like “a windshield wiper that’s getting stuck on the windshield. It isn’t smooth.”

“If I’m a tolerant drinker and I’m used to standing on one foot, that’s one thing. But you can’t control your internal functions,” he added.

When Casas performed her field sobriety test at 0.083, she said she surprised herself even with steady physical composure.

But Shoemaker said she’d still be in handcuffs if she were caught driving.

“The nystagmus alone is enough to make an arrest. She showed four out of six indicators on the nystagmus test so, yes, I would arrest her,” he said.

Training officers in the tests prepares them to make a legitimate arrest and defend it in court.

“The best way for our officers to be educated to detect, whenever they encounter a drunk driver, is by seeing one,” Shoemaker said. “And that officer can testify on the stand, ‘Yes, I have seen what a drunk or impaired person looks like.’”

The training is especially important for detecting those on the border of legality.

“We train them to be able to find that 0.06 and 0.08,” he said. “Anybody can find the 0.15. They’re falling out the door, trying to stick their license through the window.”

And the tests and training are pretty spot on, he said.

“About 90 percent of our officers can make an educated decision to arrest that person or not arrest that person,” he said.

Follow the law

Shoemaker stressed that a shaky field sobriety test alone cannot warrant an arrest if a person registers a blood alcohol level below 0.08.

“We don’t want to take a person and say, ‘Well, you just look like you’re drunk.’ If they’re below, we let them go,” he said.

Although citations can be issued at lower levels in certain circumstances.

“The per se limit for a ‘drunk driver’ is a 0.08 BAC, but you can be charged with a DUI at lesser levels, if say, you were involved in an accident,” Shoemaker said, a charge called “DUI Less Safe.”

In it’s totality, DUI law is an “intricate web” Shoemaker said, with different levels of prosecution.

When a person gets their driver’s license, Shoemaker explained, they are also giving consent for roadside sobriety testing.

“If they refuse the state-administered test, it will be used against them in court, and the state can move forward to suspend their license,” he said.

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