Alcohol Intake and Elimination Rates: When Is It Safe To Drive?Updated Sept. 28, 2020
Have you ever wondered how and why your body reacts to alcohol? Here, we introduce the biological processes which lead to drunkenness and alcohol impairment. To develop a safe and responsible relationship with alcohol, it helps to understand precisely what you’re subjecting your body to each time you take a swig of beer or a shot of hard liquor.
In addition to alcohol intake, this module discusses alcohol elimination. This is the set of processes by which your system rids itself of alcohol and restores sobriety. How rapidly and efficiently a person’s body can eliminate alcohol depends on a whole host of different environmental and genetic factors, which we will discuss in detail.
Sobriety cannot be influenced by cold showers, hot coffee or running laps of the footballs field. The passage of time is the only thing that will sober you up. When you have stopped consuming alcohol, it is only a matter of time before your system eliminates it and your body recovers. However, understand that regular or heavy alcohol consumption will eventually lead to long-term damage that your body will not bounce back from, even when you’re sober.
When you drink alcohol, it is taken into your body via ingestion – it passes through your mouth, throat, stomach and intestines and is absorbed along the way. There are other ways that alcohol and drugs can be taken, but we’ll discuss these in a later module. Most people think of ingestion as something that happens exclusively in the stomach and intestines, but in fact, the rest of the digestive tract has a part to play too. From the moment the alcoholic drink enters your mouth, you have started a chain reaction which will lead to intoxication.
Saliva begins the digestion process, allowing small amounts of alcohol to enter your blood stream directly via a network of tiny blood vessels in your mouth and throat. This process continues in the stomach, though most of the alcohol you absorb will be taken into your body via the intestines. Here, alcohol crosses the wall of your gut, passes into the blood and is transported to your liver for processing. In the liver, alcohol molecules are broken down into other chemicals which are less intoxicating but can be even more harmful than the alcohol itself. These new substances are then released back into the blood stream.
Your body’s circulatory system channels the blood stream through every vital organ, to supply the oxygen your organ tissues need to function. Therefore, any alcohol which enters your blood will also pass through these organs, including the brain. As alcohol enters your brain, it interacts with neurons and disrupts neurotransmitters (the chemicals which control your mood, physical functions and cognitive processes). Initially, alcohol will stimulate the release of feel-good dopamine, which creates the pleasant, happy feeling most people experience when they begin drinking. Then, it starts to interfere with other neurotransmitters, producing a less-positive effect:
Alcohol binds with glutamate, preventing it from doing its job. Glutamate has an excitatory effect on neurons; without it, your brain cannot respond to stimuli as quickly or efficiently. This is how alcohol slows reaction time.
Gamma aminobutyric acid (GABA).
Alcohol binds with certain receptors, enhancing the effects of gamma aminobutyric acid (GABA). GABA leads to feelings of calm and sleepiness. This further slows reaction time and interferes with your ability to think clearly.
How dramatically you experience these effects is dependent on other factors like your age, weight, experience with alcohol, food intake and state of mind prior to drinking. The effects of alcohol and other drugs on your brain’s neurotransmitters are profound. It only takes a slight imbalance in these vital chemicals for a person to experience considerable mood and personality changes. In this state, you are capable of doing things you would never dream of doing in a normal sober state. Like hopping into your car and attempting to drive home while intoxicated.
Your body rids itself of alcohol via various biological processes. Though, around 95% of all the alcohol you consume will be eliminated through metabolism. The small percentage remaining will be expelled from the body via excretion and evaporation.
Most alcohol is released from the body having been broken down into other chemicals by enzymes in the liver. However, some alcohol molecules will be released unchanged, through sweat, urine, tears and saliva. This is why heavily intoxicated people and those who drink regularly often smell of alcohol – they literally secrete it through their skin!
As blood passes through your lungs, the heat from your body causes some of the alcohol it contains to evaporate. From your lungs, the alcohol will be expelled with your breath. It is this alcohol that is being measured when a person takes a breathalyzer test.
How fast is alcohol eliminated?
The average person eliminates alcohol at a rate of 0.015% per hour. From person to person, this alcohol elimination rate varies from 0.013% to 0.018%. This figure is linked to metabolic rate. The faster your metabolism, the quicker your body will process and expel alcohol. People with slower metabolisms will have a higher BAC for longer, even when consuming the same amount of alcohol as someone with a faster metabolism.
In addition to metabolism, your alcohol elimination rate is affected by genetics and your level of experience with alcohol. A person who drinks regularly will typically have a higher alcohol elimination rate than an inexperienced drinker, as their body will have adapted to processing alcohol more efficiently.
At the average alcohol elimination rate of 0.015%, how long will it take you to sober up? That depends on your blood alcohol concentration.
- A BAC of 0.05% will be eliminated in 3.3 hours.
- A BAC of 0.08% will be eliminated in 5.3 hours.
- A BAC of 0.10% will be eliminated in 6.7 hours.
- A BAC of 0.15% will be eliminated in 10 hours.
If you decide to drink AND drive, you must consider how long it will take your BAC to drop below the legal limit of 0.08%. Then, you must factor this into your plans OR leave your car at home.
No amount of alcohol in your blood is entirely safe, so you would be wise to wait for all traces of alcohol to be eliminated before getting behind the wheel. If your BAC is 0.08% and your metabolic rate is average, total elimination will take no less than 5 hours and 20 minutes. Remember that for most people, a BAC of 0.08% occurs somewhere between 1.5 and 3 standard drinks. If you do not have the self-discipline to go out for a whole evening, drink just this amount and wait 5 hours to drive home, don’t drink or don’t drive.
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