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Alcohol

Alcohol

Alcohol acts as a depressant by suppressing the central nervous system. Within minutes of consumption, alcohol appears in the blood stream and becomes evenly distributed throughout the body. About 20% of the alcohol consumed is absorbed through the stomach and the remaining 80% is absorbed through the small intestine. Once alcohol enters the bloodstream, it is pumped to the lungs and throughout the body.

Several different types of alcohol bottles.

Factors of Alcohol in the Body

The amount of alcohol in the body depends on many factors including—the time it takes to consume the drink, the amount of alcohol in the drink, and the number of drinks consumed. Other factors include the age, weight, and gender of the person who is doing the consuming.

A close-up photo of hands clinking their glasses of beer together.

Alcohol Affects Women Differently Than Men

Interestingly, women metabolize alcohol differently than men.

  • When given the same amount of alcohol, women typically will test with a higher blood alcohol concentration (BAC) than men. This is due in part to the fact that women have less water in their bodies than men, thus the alcohol is not diluted in the same proportion as in men.
  • Also, women women have less response from the alcohol metabolizing enzyme in the stomach known as Alcohol Dehydrogenase, or ADH. Because the enzyme is less effective in women, more alcohol reaches the bloodstream of women after use.

Alcohol Side Effects for Women

It is important to note that these are not simply benign differences between men and women. Because of the difference in alcohol metabolism and decreased efficiency, women are more likely to suffer from alcohol-related liver and heart damage!

A sad woman drinking wine.

Knowledge Check #1

An infographic about alcohol metabolism. In the body, ethanol is converted into acetaldehyde, which is then coverted to acetate.
"In the body, ethanol is converted into acetaldehyde by the alcohol dehydrogenase enzyme, which is subsequently converted into acetate by the aldehyde dehydrogenase enzyme. Acetate can be broken down into carbon dioxide and water, then eliminated from the body. Acetaldehyde has been linked as a possible contributor to the symptoms of a hangover, along with dehydration and the metabolism of other molecules in alcoholic drinks."

What enzyme converts ethanol to acetaldehyde and acetate?

  1. lipase
  2. alcohol metabolase
  3. alcohol dehydrogenase (ADH)
  4. amylase

Answer: c. alcohol dehydrogenase (ADH). Alcohol dehydrogenase (ADH) converts ethanol to acetaldehyde and then acetate.

Knowledge Check #2

Why do women typically have a higher blood alcohol level after consuming the same number and type of drinks as men?

  1. Their bodies are smaller.
  2. They have fewer active enzymes for breaking down alcohol in the stomach.
  3. Their bodies have more water.
  4. Women do not typically have higher blood levels.

Knowledge Check #3

True or False: The difference in blood alcohol levels between women and men has no adverse effects.

  1. True
  2. False

Answer: b. False. Women are more likely to suffer from alcohol-related liver and heart damage.

Blood Alcohol Concentration

The amount of alcohol circulating in the body can be measured and is reported as a percentage known as blood alcohol concentration (BAC). While alcohol can affect people differently, there are predictable physical effects and impaired driving ability seen with increasing BAC levels.

The symptoms of increasing blood alcohol content (BAC). At low levels (0.02 - 0.06), symptoms include slowed reactions and a feeling of warmth. At higher levels (0.10 - 0.30), symptoms include nausea, impaired motor skills, and blackouts. 0.50 BAC causes death. The legal BAC limit in the USA is 0.08.

Open a larger version of the Symptoms of BAC in a new tab.

Blood Alcohol Levels

In 2003, every state defined the legal limit of alcohol in the bloodstream to be 0.08 percent for people who are of legal age to drink, which is typically 21 years old. Prior to that, legal limits had been as high as 0.15! See the graph below to see how much more likely a person would be to have an accident with that Blood Alcohol Content or higher!

A graph showing the relative risk of an accident based on blood alcohol levels (BAC). At 0 BAC, there is almost no relative risk. As the BAC gets higher, the relative risk gets higher.

Age Limit for Alcohol Consumption

It is important to note that while 0.08 is the legally accepted level of alcohol in the bloodstream, it affects each person in different ways. It is also important to note that there are NO acceptable levels of legal alcohol consumption in persons under the age of 21 years of age in the United States.

An almost empty bottle of alcohol turned on its side. A droplet of alcohol is hanging off the rim. In the background, a man with a glass of alcohol is resting his head on the table.

Testing for Alcohol

Because alcohol is evenly dispersed throughout the body, the amount of alcohol can be measured in numerous ways. Alcohol is excreted released from the body without being changed in form from the lungs through breathing, the pores by sweating, and from the kidneys by urination. Therefore, alcohol can be smelled on the breath and in the sweat of someone who has recently been drinking it. The body attempts to get rid of it in these ways directly. Alcohol in the blood will pass directly into the alveoli of the lungs where it will be passed out through the mouth and nose as the person breathes.

Breathalyzers

Breathalyzers reflect the amount of alcohol that is in the pulmonary lung artery at the time of the test.

Breath testers use infrared light or fuel cells to measure the concentration of alcohol in the breath and are typically conducted by law enforcement officers in the field. They work by shining an infrared light through the chamber where the breath is captured. As the light passes through the chamber, it will interact with the alcohol and cause the light density to decrease. The decrease in light intensity is proportional to the concentration of alcohol present in the captured breath.

A diagram of a breathalyzer. The breath enters the chamber at the top, goes through an infrared light, and exits through the bottom. There is an infrared detector at the end of the chamber.

Testing for Alcohol in the Forensic Laboratory

In the forensic laboratory, toxicologists collect blood, urine, and vitreous humor clear, gel-like substance that fills the eye samples and test them by using gas chromatography. However, urine samples do not reflect the amount of alcohol currently in the bloodstream, but rather what has been eliminated. These concentrations can vary widely depending on the amount of other liquids consumed.

Field Sobriety Test

Field sobriety tests are sometimes used in the field by police officers as a type of screening test to either ascertain the level of impairment of the person or to see if further alcohol testing is needed in conjunction with a traffic or legal infraction.

A police officer giving a man a field sobriety test.

Horizontal Gaze Nystagmus

Field sobriety tests include various physical tests such as the "walk and turn", "stand on one leg" and "Horizontal Gaze Nystagmus" test the eyes will involuntarily jerk as an impaired person looks from one side to the other When impaired by alcohol, a person has difficulty dividing their attention and maintaining balance; this is the basis for those screening tests of sobriety.

Calculating BAC

While BAC levels can be directly measured, these values can change within hours of alcohol consumption. The Widmark equation can be used to estimate BAC levels based on the number, size, and concentration of the drinks consumed as well as the weight and gender of the person.

Male Formula: A times D times 5.14 over Wt times 0.73.

Female Formula: A times D times 5.14 over Wt time 0.66.

A = Alcohol consumed in ounces (oz.)

D = % alcohol written as a decimal (example: 6% = 0.06 and 40% = 0.40)

Wt = weight of the person in pounds (lbs.)

 

The amount of alcohol (A) and % alcohol (D) can be determined based on the type of drink consumed.

Type of drink Average amount in oz % of alcohol
Beer 12 oz 6%
Wine 5 oz 12%
Hard liquor (shot) 1.25 oz 40%

Calculating BAC: Example #1

A 230 lb. male consumes 2 beers in less than an hour. What is his BAC level?

  1. The male formula is used. BAC = A times D times 5.14 over Wt times 0.73.

  2. The amount (A) in this example is 12 oz. × 2 (24 oz.). The % alcohol (D) in the formal of a decimal is 0.06. The weight of the person (Wt) is 230 lb. These values are placed appropriately into the equation.

    BAC 24 times 0.06 times 5.14 over 230 times 0.73.

  3. The numerator and denominator are multiplied separately. BAC 7.402 over 165.6
  4. Those values are then divided to find the BAC level. BAC = 0.045.

Knowledge Check #4

This value is below the legal limit. What effects would you expect at this BAC?

  1. slurred speech
  2. nausea
  3. short-term memory loss
  4. lowered alertness

Answer: d. lowered alertness

Knowledge Check #5

What is the BAC level of a 145-lb. female who consumes 3 glasses of wine in a short period of time?

  1. 0.097
  2. 9.252
  3. 0.019
  4. 0.97

Answer: a. 0.097. BAC = 15 times 0.12 times 5.14 over 145 times 0.66., BAC 9.252 over 95.7, BAC = 0.097

Widmark Formula Modified

The Widmark formula is modified for alcohol consumed over a long period of time by adding the following calculation:

  1. Estimate the hours since drinking commenced
  2. Multiply the hours × 0.015
  3. Subtract this value from the BAC calculation

Calculating BAC: Example #2

A 150 lb. male consumes a six pack of beer over a 3-hour period of time. Determine the BAC for this person.

  1. First, the BAC is determined using the male formula. BAC = A times D times 5.14 over Wt times 0.73.

  2. The given values for weight, amount, and concentration are used in the equation. (6 beers × 12 oz each = 72 oz)

    BAC 72 times 0.06 times 5.14 over 150 times 0.73.

  3. The numerator and denominator are multiplied separately. BAC 22.2 over 109.5
  4. Those values are then divided to find the BAC level. BAC = 0.203.
  5. Multiply the hours since drinking commenced × 0.015. 3 × 0.015 = 0.045
  6. Subtract this value from the calculated BAC. BAC = 0.203 - 0.045, BAC = 0.158.

Knowledge Check #6

This value is above the legal limit for drivers over the age of 21. What effects would you expect to see at this BAC level?

  1. difficulty standing
  2. nausea
  3. difficulty maintaining lane position
  4. All these effects would be seen at a BAC level of 0.158.

Answer: d. All these effects would be seen at a BAC level of 0.158.

Knowledge Check #7

A 150-lb female has 3 mixed drinks (shots) one right after the other. It has been two hours and she is ready to go home. Is her BAC low enough for her to drive home? Calculate her BAC after two hours.

  1. 7.71
  2. 0.0779
  3. 0.0479
  4. 0.1079

Answer: c. 0.0479. BAC = 3.75 times 0.40 times 5.14 over 150 times 0.66., BAC = 7.71 over 99, BAC = 0.0779 - (2 × 0.015), BAC = 0.0779 - 0.03, BAC = 0.0479. While her BAC is below the legal limit, it would still be safer for her to have a designated driver take her home.

Calculating BAC: Example #3

The equation can also be used to evaluate whether a person is truthfully reporting the number of drinks they’ve consumed based on a measured BAC level.

An officer pulls over a 125-lb woman and gives her a field sobriety test followed by a BAC test. The breathalyser indicates a BAC of 0.085. The woman claims she only drank two beers. If it is true that she drank beer, how many did she really have?

  1. The female BAC equation is used. BAC = A times D times 5.14 over Wt times 0.66.

  2. The known values for BAC, alcohol concentration (D) and weight are put into the equation while the amount of alcohol (A) is not known.

    0.085 A times 00.6 times 5.14 over 125 times 0.66.
  3. The numerator and denominator are multiplied separately. 0.085 A times 0.3084 over 82.5.
  4. Both sides are multiplied by 82.5.   7.0125 = (A)(0.3084)
  5. Both sides are divided by 0.3084.   A = 22.7 oz.

This is the amount in oz. If each beer is 12 oz., the woman is telling the truth.

Knowledge Check #8

How many shots did a 175-lb male with a BAC of 0.10 consume? Assume the shots were consumed within the last hour.

  1. 2 shots
  2. 3 shots
  3. 4 shots
  4. 5 shots

Answer: d. 5 shots. BAC = A times D times 5.14 over Wt times 0.73., 0.10 = A times 0.40 times 5.14 over 175 times 0.73., 0.10 = A times 2.056 over 127.75., 12.775 = (A)(2.056), A = 6.21 oz. This value is in oz., the equivalent of approximately 5 shots (5 × 1.25 oz. = 6.25 oz.)

Adverse Effects of Excessive Alcohol Consumptions

While we often associated alcohol consumption with the danger of drunk driving, studies show that excessive alcohol consumption can have numerous adverse effects, both immediate and long-term.

Alcohol is a factor in the deaths of thousands of people younger than age 21 in the United States each year. This includes:

  • 1,072 from motor vehicle crashes.
  • 1,000 from homicides
  • 208 from alcohol overdose, falls, burns, and drowning
  • 596 from suicides

Alcohol-related Deaths

An estimated 95,000 people (approximately 68,000 men and 27,000 women) die from alcohol-related causes annually, making alcohol the third-leading preventable cause of death in the United States. The first is tobacco, and the second is poor diet and physical inactivity. Alcohol-attributable deaths include associated liver disease and cancer, heart disease, stroke, and hypertension high blood pressure .

A man clutching his chest in pain.

Excessive Alcohol Use

Read more about excessive alcohol use in this infographic from the Centers for Disease Control and Prevention (CDC). You may open a larger version of the Excessive Alcohol Use diagram in a new tab.

An infographic about excessive alcohol use. Excessive drinking includes binge drinking, underage drinking, heavy drinking, and pregnant drinking.
Excessive alcohol use includes: binge drinking (4 or more drinks consumed on one occasion for women, and 5 or more drinks consumed on one occasion for men), any alcohol use under the age of 21, heavy drinking (8 drinks more one per week for women, and 15 drinks or more per week for men), and any alcohol use by pregnant women.
An infographic about what is considered an alcoholic drink in the U.S. and how excessive drinking affects us.
What is considered a drink? U.S. standard drink sizes: 12 oz. of 5% alcohol by volume (ABV) beer, 8 oz. of 7% ABV malt liquor, 5 oz. of 12% ABV wine, and 1.5 oz. of 40% (80-proof) distilled spirits or liquor (examples: gin, rum, vodka, whiskey). How does excessive drinking affect us? 88,000 deaths per year; violence, injuries, and motor vehicle crashes; risky sexual behaviors (unintended pregnancies, miscarriages, and stillbirth); chronic conditions (cancer, heart disease, and high blood pressure); and 249 billion dollars in economic cost.
An infographic about binge drinking and the problems associated with it.
Binge drinking is the main problem. Over 90% of excessive drinkers binge drink. 1 in 6 adults, or more than 38 million adults, binge drink. Binge drinkers do so about 4 times a month. Binge drinkers average 8 drinks per binge. Most people who binge drink are not alcohol dependent or alcoholics.
An infographic about drinking in moderation.
If you choose to drink, do so in moderation. No one should begin drinking or drink more frequently based on potential health benefits. For women, moderate drinking is up to 1 drink a day, and for men, up to 2 drinks per day. Do not drink at all if you are under age 21, pregnant or may be pregnant, or have health problems that could be made worse by drinking.

Knowledge Check #9

How many deaths in the U.S. are attributed to excessive drinking each year?

  1. 90%
  2. 249 billion
  3. 1 in 6
  4. 88,000

Answer: d. 88,000

Knowledge Check #10

According to the CDC infographic above, the main problem with drinking is _________.

  1. addiction to alcohol
  2. regular drinking
  3. binge drinking
  4. underage drinking

Answer: c. binge drinking

Knowledge Check #11

What chronic conditions are associated with excessive drinking?

  1. high blood pressure
  2. heart disease
  3. cancer
  4. All these are associated with excessive drinking.

Answer: d. All these are associated with excessive drinking.

Credits

"Alcohol Facts and Statistics." National Institute on Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, updated March 2021, www.niaaa.nih.gov/publications/brochures-and-fact-sheets/alcohol-facts-and-statistics.