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Explaining Alcohol to Teens

March 31, 2015 by HealthyFamilies BC


Talking to teens about alcohol and helping them understand what happens to the body when drinking alcohol and what factors influence intoxication can guide them towards safe decisions. Use this information as a guide to explain how alcohol works and why it affects us the way it does.

Alcohol starts to slow thinking, movement and speech as soon as it reaches the brain. How does it get to the brain?

The alcohol you drink moves into the bloodstream from the stomach and small intestine. The amount of alcohol in the blood is called blood alcohol content (BAC). The higher your blood alcohol level, the greater the slow-down effect on your brain and other parts of the central nervous system.

Alcohol is largely metabolized (broken down into carbon dioxide and water) by the liver for removal by the lungs and urine. When all the alcohol is processed and eliminated from the body, BAC returns to zero.

What Affects Blood Alcohol Content (BAC)?

  • Amount: The more alcohol, the higher the BAC.
  • Speed: The faster the drinking, the higher the BAC.
  • Absorption: Food in the stomach slows down the rate of absorption of alcohol (meaning BAC rises more gradually in a body with a full stomach than in a body with an empty stomach).
  • Weight: The smaller the body size, the higher the BAC for the same amount of alcohol (larger bodies have more water than smaller bodies to dilute alcohol).
  • Gender: A woman will have a higher BAC than a man after drinking the same amount because
    • women’s bodies have less water - 50% compared to 60% for men,
    • women also have smaller livers and less of the dehydrogenase enzyme involved in metabolizing or breaking down alcohol, and
    • women’s hormonal cycles and birth control pills impact metabolism rates.
  • Age: People tend to lose lean body mass as they age, resulting in more body fat and less water in the body to dilute alcohol. Older bodies also process alcohol less effectively, putting an extra burden on the liver and producing a higher blood alcohol content.
  • Metabolism: the liver metabolizes alcohol at a fairly fixed rate (about .016% BAC every hour for men, a lesser amount for women).
  • Time: Despite common beliefs that coffee, cold showers or exercise can quickly sober you up, time is the only thing that can bring BAC back to zero.

What Happens as Blood Alcohol Content (BAC) Rises?

How and how much alcohol affects your behaviour - and how obvious it is to others - depends on your drinking experience, how much tolerance for alcohol you have, and your situation. Here’s a scale of BAC levels and what may be experienced as BAC rises.

  • .00 = Relaxed buzz
  • .05 = Less inhibited, more sociable feeling of well-being
  • .10 = Serious impairment of motor coordination and judgment ability
  • .15 = Sloppy, disoriented demeanour
  • .20 = Memory blackouts, danger of choking on vomit
  • .25 = Medical assistance may be necessary
  • .30 = Hospitalization may be required, may have alcohol poisoning, passed out in a stupor
  • .35 = Coma
  • .40 = Death from respiratory failure

How Blood Alcohol Content (BAC) is Measured?

Blood alcohol content (BAC) is usually given as a percentage showing how much alcohol (measured in milligrams) is in a 100 millilitres of blood. For example, a BAC of 0.08 per cent is 80 milligrams of alcohol for every 100 millilitres of blood.

One way to measure BAC is through breathalyzer instruments, like those used by police to prevent people from driving impaired. In British Columbia, the legal drinking limit for operating a motor vehicle is a BAC of .05 per cent - anything higher can result in penalties under provincial laws.

Use BAC tables or online calculators to see what your BAC levels might be while drinking. These tools aren’t 100 per cent accurate, but provide a rough guide to understand how having multiple drinks over time affects BAC. Knowing how having three drinks over the course of two hours will make you feel can help you set safer limits for yourself.


BAC Women

Canada’s Low-Risk Drinking Guidelines state you can reduce your long-term health risks by drinking no more than:

  • 10 drinks a week for women, with no more than 2 drinks a day most days
  • 15 drinks a week for men, with no more than 3 drinks a day most days

And, plan non-drinking days every week to avoid developing a habit.


Resources & Links:

Canadian Center on Substance Abuse: Canada’s Low Risk Alcohol Drinking Guidelines
Road Safety: Driving While Affected by Drugs or Alcohol
ICBC: Impaired Driving


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