What factors determine your blood alcohol content (BAC)?

If you were arrested for DUI, you likely registered a blood alcohol content (BAC) of at least .08 percent on a Breathalyzer test administered by the officer who pulled you over. It’s illegal throughout the country to drive with a BAC at that level. You may not know, however, just what “blood alcohol content” refers to and what factors can impact it.

Your BAC is how much alcohol is in your bloodstream. A .08 percent BAC means you have 8 milligrams (mg) of alcohol in your system for every 10,000 mg of blood.

That number wasn’t chosen randomly. It’s based on extensive research into what a person’s BAC is when alcohol begins to impair their ability to safely operate a vehicle. Did you know that back in 1938, the most common BAC legal limit was .15 percent?

Everyone metabolizes alcohol differently. Two drinks for a 200-pound man probably won’t put his BAC anywhere near the legal limit. However, two drinks for a 100-pound woman will likely place her over that limit.

It’s not just a matter of size and weight. Men have more water in their bodies than women. That dilutes any alcohol they consume. Further, women have fewer stomach enzymes than men. That means they can’t break down the alcohol in their system as quickly.

A person’s body type — regardless of gender — also plays a role. Muscle absorbs more alcohol than fat. Therefore, two people of the same weight can absorb alcohol differently based on whether that weight is predominantly fat or muscle.

Other factors, such as your metabolic rate and stress level and impact how your body absorbs alcohol and how quickly it goes into your bloodstream. So can the amount of food in your stomach. Of course, many medications (legal and illegal) have a significant impact on a person’s reaction to alcohol.

How quickly you’re drinking impacts the rate at which the alcohol is absorbed into your system. If you down multiple drinks one after the other, the body has no time to absorb the alcohol.

You can’t make a guessing game out of your BAC or even look at a chart and determine what yours is at any given moment.

Breathalyzers aren’t error-proof. Neither are the officers who administer them. If you’re arrested for DUI, your attorney can investigate the test results and look at other options for defending you against the charges.