The amount of alcohol in a person's body is measured by the presence of alcohol in a certain blood volume. This is called blood alcohol concentration, or "BAC." A driver's BAC can be measured by testing the blood, breath, urine, or saliva.

What is Blood Alcohol Concentration?

Posted On: May 23, 2024

If you’ve ever glanced at the label of your favorite beer or wine, you might have seen the letters “BAC” on the bottle, along with a number. While many of us have stumbled upon this acronym without fully understanding its significance, it’s especially important for alcohol servers to know in order to serve responsibly.

In this blog, we’ll help you gain an understanding of BAC's intricacies for safe alcohol consumption and legal compliance.

Blood Alcohol Concentration Defined

Blood alcohol concentration, commonly referred to as BAC, determines an individual’s level of intoxication. It measures the percentage of alcohol in one’s blood and is shown as a ratio of alcohol to blood in the body. For reference, someone with no alcohol in their system will have a BAC of 0.00.

Having a system in place for assessing an individual’s ‘drunkenness’ has allowed states to create laws and policies around what people can and cannot due under the influence. For example, in a collective effort to reduce fatalities on the road, all 50 states agreed to enforce a BAC for drivers of 0.08% in 2004.

This means that anyone 21 and up is legally intoxicated and unable to drive safely when 8/10ths of a milliliter of alcohol is present in every 1000 milliliters of their blood. It sounds complicated, but it typically only takes a couple of drinks to hit that limit.

How Is BAC Measured?

BAC is determined through tests on blood, breath, urine, or saliva, with breath tests being a popular method due to their convenience and reliability. Factors such as weight, gender, and the speed of consumption influence BAC levels, making its calculation complex. For instance, women generally reach higher BAC levels faster than men under similar conditions due to differences in body composition and metabolism.

Education on BAC is also crucial for restaurant staff and bartenders, who often use charts to estimate patrons' intoxication levels, aiding in responsible service decisions.

Some other factors that affect BAC include:

Drinking on an empty stomach
The rate of the person’s drinking
The ratio of body fat (body fat does not absorb alcohol)
Metabolic rate (affected by diet, digestion, fitness, emotional state, hormonal cycle, time of day, year, etc.)
Tiredness also affects concentration and absorption
Individual differences in size, weight, and metabolism
The percentage of alcohol in the drink
Type of alcohol (fizzy drinks are absorbed more quickly)
The amount of time since the last drink (the body can only break down about 1/2 a drink an hour)

Using stimulants, such as caffeine, won’t affect BAC but may ‘mask’ the effect of alcohol, making you feel soberer than you are.

Alcohol Absorption and Elimination

The process of alcohol absorption and elimination from the body is influenced by various factors. Alcohol is absorbed into the bloodstream through the stomach and small intestine, with the rate of absorption affected by the drink's alcohol content, the presence of food in the stomach, and the individual's drinking pace.

Once absorbed, the liver metabolizes alcohol at a constant rate, with most alcohol being processed by the body, while a small percentage is excreted unchanged.

Factors Affecting Alcohol Absorption and Elimination:

The presence of food in the stomach can slow the absorption of alcohol, reducing BAC spikes.
The type and concentration of alcohol consumed, as higher alcohol content drinks are absorbed faster.
The individual's metabolic rate can vary due to factors like diet, physical fitness, and hormonal cycles.

Individual Differences in BAC

BAC levels are not uniform across individuals, influenced by:

Body weight and composition: Larger individuals typically have lower BAC levels after consuming the same amount of alcohol as smaller individuals due to the dilution effect.
Gender: Women often experience higher BAC levels than men due to differences in body composition and alcohol metabolism.
Metabolic rate: Variations in how quickly an individual's body processes alcohol can lead to different BAC readings.

Understanding these differences is vital for individuals to gauge their alcohol consumption more accurately and for servers to make informed decisions about serving alcohol.

What Are the Risks of Having a High BAC?

The faster someone drinks, the higher the BAC is, and the more dangerous drinking becomes. Here’s an overview of how alcohol consumption can affect a person based on different BAC levels:

BAC .02 – Drinkers begin to feel moderate effects.
BAC .04 – Most people feel relaxed, mildly euphoric, sociable, and talkative.
BAC .05 – Judgment, attention, and control are somewhat impaired. The ability to drive safely begins to be limited. Sensory-motor and finer performance are impaired. People are noticeably less capable of making rational decisions about their capabilities (for example, about driving.)
BAC .08 – This is the legal level for intoxication in some states. There is a definite impairment in muscle coordination and driving skills.
BAC .10 –This is legally drunk in most states. There is a clear deterioration in reaction time, control, and hand-eye coordination.
BAC .12-.15 – Vomiting usually occurs unless this level is reached slowly or if an individual has developed a strong tolerance to alcohol. In addition:
- Drinkers are drowsy.
- Drinkers display emotional instability, loss of critical judgment, and impaired perception, memory, and comprehension. Lack of sensor-motor coordination and impaired balance are typical.
- Decreased sensory responses and increased reaction times develop.
- The vision is significantly impaired, including limited ability to see detail, peripheral vision, and slower glare recovery.
BAC .15 – This blood-alcohol level means the equivalent of 1/2 pint of whiskey is circulating in the bloodstream.
BAC .18-.25 – Drinkers are disoriented, confused, dizzy, and have exaggerated emotional states. Vision is disturbed, as is the perception of color, form, motion, and dimensions. Drinkers may also experience increased pain threshold and lack of muscular coordination. Furthermore, they may stagger or lose the ability to walk and have slurred speech. Apathy and lethargy are typical.
BAC .25-.30 – Drinkers display general inertia, near-total loss of motor functions, little response to stimuli, inability to stand or walk, vomiting, and incontinence. Drinkers may lose consciousness or fall into a stupor.
BAC .30-.50 – Symptoms are complete unconsciousness, depressed or absent reflexes, subnormal body temperature, incontinence, and impaired circulation and respiration.

Death may occur at .37% or higher, while BACs of .45% and higher are fatal to nearly all individuals.

Role of Alcohol Servers in Serving Responsibly

Alcohol servers play a pivotal role in promoting safe drinking practices. Through training programs, servers learn to:

Recognize signs of intoxication.
Understand the legal responsibilities of serving alcohol.
Make informed decisions about when to refuse service to prevent overconsumption and ensure patron safety.

Best Practices for Responsible Service:

Refusal procedures: Establishing a clear protocol for when and how to refuse service to patrons.
Standardized serving sizes: Ensuring consistency in alcohol serving sizes to prevent unintentional overconsumption.
Comprehensive staff training: Beyond bartenders and servers, training all staff members in recognizing intoxication signs and responsible service principles.
Effective communication systems: Facilitating communication among staff regarding patrons' intoxication levels and appropriate actions.
Safe closing procedures: This includes last calls and assessing patrons' sobriety before departure, offering alternatives like taxi services if necessary.

Ensuring the responsible service of alcohol not only protects patrons but also helps establishments maintain a positive reputation and comply with legal standards.

By understanding and addressing the complexities of BAC, alcohol absorption and elimination, and individual differences, both consumers and servers can contribute to a safer and more enjoyable drinking environment.

Using BAC Awareness To Maintain Order at the Bar

A strict alcohol program must ensure the certification of all servers through a state-sanctioned Alcohol Seller Training program.

After that, it’ll be on the management team to lead by example and enforce the rules and standards without exception. Making responsible service part of the culture will help the establishments avoid penalties and negative publicity.

Moreover, identifying BAC levels can be very tricky for those without prior experience. Thus, aside from training, an accessible support system that may come in the form of documents, charts, or tools must be available for all the staff who are serving alcohol.

Stay Compliant With Learn2Serve

Understanding the concept of Blood Alcohol Concentration and recognizing the effects of varying BAC levels on cognitive and motor functions is crucial for personal safety and the well-being of others. To ensure a commitment to responsible drinking, consider investing in an alcohol server training course such as those provided by Learn2Serve by 360training. Such courses provide invaluable insights into alcohol consumption, its effects on the body, and strategies for harm reduction. Visit our website today to explore our comprehensive alcohol server training courses.