Originally alcohol tests were administered by collecting blood samples. As the science evolved it was discovered that alcohol was also present in exhaled air, in urine and saliva. Referring to this, scientists say that 85% alcohol gets eliminated through the process of metabolism and the rest is evaporated into the breath or eliminated in urine and saliva.
New techniques and instruments were invented to test the alcohol in the body. At first, such instruments were expensive and difficult to use, but nowadays modern electronics has created fast analytical systems, which make an alcohol test cheap and much more convenient to use.
Testing the Breath Alcohol
Testing the level of alcohol in the breath is a simple and non-invasive technique, which measures the level of alcohol exhaled by normal breathing. There is a direct correlation between a person’s blood alcohol concentration and his breath alcohol content. Breath alcohol testers are nowadays very diverse and designed for a large category of population. They can vary from disposable screening testers to the modern and very expensive digital breath alcohol monitors to the affordable hand-held digital alcohol testers.
How to use a breath alcohol tester
A common tester has a balloon and a glass tube with yellow crystals, which turn green when they get in contact with alcohol molecules.
The tested person exhales into the balloon, with one continuous breath. The balloon’s mouthpiece is fitted to the end of the glass tube. The alcohol content of the exhaled air is measured by counting the number of bands in the tube that have changed from yellow to green. This reflects the alcohol content of the blood.
A calibrated breathalyzer machine is also available to check a person’s alcohol level. With a calibrated breathalyzer the person blows into a mouthpiece, and the machine displays the alcohol level in digital format. This is more accurate than the balloon type test.
What do the results mean?
If a person is completely sober, then the blood alcohol concentration (BAC) level is zero and the yellow bands in the tube will not change color. The exhaled air contains no alcohol.
- At 0.00 BAC to 0.05 BAC, the band will turn green.
- At 0.05 BAC to 0.10 BAC two bands will turn green.
- For 0.10 BAC to 0.15 BAC, three bands turn green. At these levels, a person is considered legally drunk in all states.
Testing the Blood Alcohol
The level of alcohol in the body can also be measured by examining a blood sample. This test is nothing but a normal procedure of taking blood out from a vein. Alcohol is quickly absorbed into the blood and can be measured within 40 to 70 minutes after having consumed any alcoholic drink. The amount of alcohol in the blood reaches its highest level about an hour after drinking. The presence of food in the stomach may increase the amount of time it takes for the blood alcohol to reach its highest level.
The methodology used for testing the blood alcohol is called Gas Chromatography and is the most accurate forensic quality test in the industry today. However, drawing blood is an invasive and expensive procedure that most companies prefer to avoid.
Testing the Saliva Alcohol
Saliva tests are not so often used. Although there is a correlation between blood alcohol concentration and saliva alcohol concentration, the technology itself is not fully reliable. Some saliva testers seem to indicate the presence of alcohol but high or low cold temperatures easily effect the enzyme alcohol oxidize used in these testers. However, the saliva test is a screening method only. This means that any result, which is non-negative, is considered a presumptive positive and has to be confirmed in order to be legally defensible.
Testing the Urine Alcohol
Urine alcohol testing is not as accurate as the blood or breath testing. Urine indicates the alcohol in the body but not the person’s present condition. In other words alcohol is metabolized by the body and appears in the urine after almost 2 hours. It’s obvious that what a urine test measure is the condition of the person 2 hours before his present state.
More than this, urine alcohol concentration does not have the same correspondence to blood alcohol concentration because it depends on the person’s metabolism. If you have a lot of liquids in your body, your alcohol concentration will show lower. Another inconvenience is that it is not readily available since the sample is tested at a laboratory hours after the collection. Therefore, it is not helpful when time plays an important role.