Blood Alcohol Concentration (BAC) is the level of alcohol present in blood after drinking. BAC is considered to be the standard for measuring the degree to which an individual is impaired by alcohol. There are more ways to test BAC, but blood alcohol testing offers the most accurate results. As a disadvantage, this testing is an intrusive and sometimes painful technique, and the analysis process can be time consuming and expensive.
What is the blood alcohol test?
As the term implies, a blood alcohol test is a normal venipuncture procedure of taking blood out of a vein. The blood is drawn from a vein, usually from the inside of the elbow or the back of the hand and then analyzed for the presence and percentage of alcohol.
Blood alcohol tests are performed for:
- Measuring the BAC when a person is suspected of being legally drunk and driving or working;
- Evaluate the cause of impaired state of mind, such as unclear thinking, confusion, or coma;
- Establish whether alcohol is present in the blood for the population for which alcohol is forbidden (underage people suspected of drinking or in people enrolled in an alcohol treatment program).
Results of blood alcohol test
The results are normal if no alcohol is found in the blood. At BAC between 0.08-0.10 mm/l, the person is legally intoxicated, according to the legislation of most states.
Factors that affect the blood alcohol level
There are some factors that play an important role in the metabolism of alcohol. In other words the rate of metabolism is about 8.5 g of alcohol per hour but this varies among individuals depending on factors like:
- Number of drinks per hour. The more you drink, the higher the BAC goes.
- Weight. The more you weigh, the more water is present in your body, which dilutes the alcohol and lowers the blood alcohol level;
- Age. One drink raises the blood alcohol level of an older adult 20% more than it does for a young adult;
- Sex. Women’s tissues have less water and more fat than men’s bodies. Alcohol does not go into fat cells so women tend to retain more alcohol in their blood;
- Food in your stomach absorbs some of the alcohol; in this case the alcohol concentration will be higher if you do not eat before or during drinking,
- Other medication in combination with alcohol emphasizes the perception of alcohol in the body. Also, a person who uses other drugs, such as marijuana, will feel the effects of both drugs more than if the drugs were used separately.
Special concerns when doing a blood alcohol test
A blood alcohol test cannot indicate for how long you have been drinking or whether you have an alcohol problem. Such a test can only measure the amount of alcohol in the blood at the time the sample is taken.
Another problem is the time between drinking and collecting the blood sample, which will influence the test results. The alcohol is metabolized steadily after drinking. In general, the body breaks down about one drink per hour.
On the other hand, if a person ingests a significant amount of alcohol shortly before the test, their BAC will actually increase after the test.
Resources
Breathalyzers.net – distributes several different hand-held models, including the highly regarded AlcoMate Digital hand-held unit for consumers, and the Lifeloc FC for professional use.
Also see:
Alcohol breath tester
Types of alcohol tests
Alcohol testing using saliva
Breath alcohol analysis
Breath alcohol test
