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Breaking Point: How Much Alcohol Can The Human Body Take At Once?

“I have no idea how I got home yesterday, I totally blacked out. So wasted!”

It’s a statement commonly met with snorts of laughter on college campuses across the nation. Binge drinking to the point of memory loss, vomiting, passing out — it just comes with the territory. Though alcohol and excessive drinking may be viewed by students and many others as a casual social activity, alcohol can have deadly effects. No matter how often high schools and colleges try to impress this upon students, the idea never sticks: in 2013, 24.6 percent of people aged 18 or over reported binge drinking in the previous month.

There are more than 2,200 alcohol poisoning deaths in the United States each year, more than “harder” drugs including MDMA, methamphetamine, and psychedelics. But exactly how much of America’s favorite drug does it take to kill you?

A Stimulating Depressant

Alcohol is considered both a food, since it contains calories and you (usually!) consume it through your mouth, and a psychoactive drug, since it can alter human consciousness. Ethanol is the source of an alcoholic beverage’s effect, and these calories are empty: they have no nutrient value, so the substance cannot be digested like other foods.

“Instead of being converted and transported to cells and tissues, it avoids the normal digestive process and goes directly to the blood stream,” wrote Dr. Michaele P. Dunlap, a Portland-based clinical psychologist. “About 20 percent of the alcohol is absorbed directly into the blood through the stomach walls and 80 percent is absorbed into the bloodstream through the small intestine.”

It is only when alcohol hits the bloodstream and begins diffusing into the body’s cells that its psychoactive effects begin to take place.

Perhaps the most important reason for alcohol’s popularity is its ability to lower inhibitions and create a social atmosphere that’s friendly and loose. Anyone who’s had a glass of wine or two knows that after that last drop, conversation comes easier and relaxation sets in. Since people may feel more animated and social after drinking, they may be tempted to label the substance as stimulating. These effects are misleading, however, since alcohol is really acting as a depressant on the central nervous system (CNS).

Alcohol targets certain cells in the brain, binding to receptors and mimicking the effect of some neurotransmitters. One of these neurotransmitters is called GABA, which inhibits nerve transmission in the brain, producing a calming effect over the nervous system. Drinking also causes the suppression of glutamate, which normally increases brain activity.

These actions cause the dreamy, relaxed feeling of being intoxicated, but alcohol also increases the release of dopamine in the brain’s reward center, which could explain why many users report feeling stimulated and euphoric.

Measuring The Influence

Since alcohol begins affecting us when it reaches the blood, our level of intoxication is measured in blood alcohol content (BAC). This refers to the weight of pure ethanol per unit of blood — in North America, for example, a BAC of 0.1 means 0.1 percent of your blood is alcohol.

The good effects of alcohol — euphoria, social ease, reduced anxiety — usually manifest when a person’s BAC is around 0.03 to 0.08. Even at this relatively low BAC, a few negative effects can manifest, including decreased ability to concentrate, poor reasoning and judgement, and decreased sensitivity in depth perception.

For the most part, this is the sweet spot for any enjoyable effects of alcohol, and the driving limit in the U.S. is a BAC of 0.08.

It’s past this point that things get uncomfortable, dangerous, and even deadly. After a while, alcohol stops releasing dopamine and the enjoyable effects of consumption begin to wear off.

“When you do too much of a drug, like alcohol, that releases all of those good things, they also trigger your stress axis,” George Koob, director of the National Institute on Alcohol Abuse and Alcoholism told Vice. “So then you end up with these chemicals in your brain that end up making you feel terrible.”

Terrible could describe many effects of alcohol past the 0.08 mark — motor control starts to diminish around 0.1, as does the ability to speak clearly or walk straight. This is also the point at which nausea and vomiting become a possibility, along with temporary erectile dysfunction.

If a person continues to drink past this, they’ll experience impaired sensation, loss of consciousness and memory around 0.2, diminishing bladder function and difficulty breathing around 0.3. This level, Koob warns, is somewhere you want to avoid.

“Zero-point-three to 0.4 percent, and you’re in the danger zone,” he said. “People have actually died at those levels.”

Most experts agree that the lethal dose, which describes a BAC that produces death from alcohol in half the population, falls into the 0.4- percent to 0.5-percent range.

There have been miraculous (and somewhat unsubstantiated) cases of people surviving higher BACs than 0.5, but as a general rule, humans can’t take more than this. As Koob expressed, though, avoiding anything even close to this is a better idea than trying to push the limit — many factors can influence both your BAC, and the BAC that will produce death in you as an individual.

Drinking To Death

When a person drinks heavily, central nervous system function deteriorates in a predictable way — first cognitive function is decreased, followed by motor and sensory control, then finally the functions we think of as automatic, like breathing and heartbeat. Here’s where things get deadly: A person with a BAC around .4 will lose control of their breathing and heart rate, which can become so depressed they fall into a coma.

There’s a high possibility of death at this point, but how do you know when you’re getting to this point if the alcohol has already ravaged your cognitive abilities?

Obviously, the safest way to avoid alcohol poisoning is to totally abstain from drinking — something 86.8 percent of American adults have chosen not to do. A more reasonable approach would be to know the risk factors for reaching the danger zone of BAC.

Drinking on an empty stomach, drinking higher-proof alcohol, and even just being a woman can up your risk of reaching a high BAC. Simple things like drinking water between alcoholic drinks to slow down the pace at which you consume alcohol can not only stave off undesirable effects of the drug and hangovers, they can save your life.