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Several different methods are available for alcohol testing. Alcohol
test can be done via blood draw, breath, urine or saliva.
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Blood
Alcohol Testing
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Blood
Alcohol Concentration (BAC) is considered to be the standard for
measuring the degree to which an individual is impaired by alcohol.
For years, studies have shown that there is a direct correlation
between the blood alcohol concentration and the degree to which
reactions and judgments are impaired. The methodology used for blood
alcohol testing is 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.
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Breath Alcohol Testing
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It
is well proven that there is a direct correlation between a person's
blood alcohol concentration and his breath alcohol contents. During
respiration, gas is exchanged from the lungs to the blood (primarily
oxygen) during inhalation, and visa versa (primarily C02) during
exhalation. During this exchange, alcohol in the blood vaporizes
cross the lungs membrane into the exhaled breath. There are
several types of breath alcohol testing devices available today. These range
from disposable screening testers to the equipment that provides
legally admissible test results, or devices ideal for screening purpose by companies as well as individuals . including very expensive digital read-out
breath alcohol monitors. These types of testers fall into three
categories:
- Evidential Breath Testing Devices, usually a table top equipment
- Non Evidential or Screening Only Devices, Usually Portable/Hand Held
- Disposable Devices For Forensic and Non Forensic Results
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The
evidential breath testing devices are generally
expensive (costs range from $3000-$5000 per unit), require regular
maintenance, repair and calibration, and must be operated by Certified
Personnel. Attachments such as sterile mouthpieces must be used
each time a test is performed. These units are large table top units
designed to be used in one location. Movement and environmental changes can effect the calibration parameters and settings which require recalibration and maintenance.
The
portable hand held devices provide fairly accurate
results and are used for screening purposes. By measuring the alcohol
content in the breath, a reliable indication of the blood alcohol
level is achieved. Portables devices are less accurate than evidential
devices, however by comparing the cost performance ratio, these
devices are affordable and sufficient for personal and corporate screening usage. Most potable
devices are not evidential and not admissible in
the court of law.
The
disposable devices are noninvasive,
and non scalable methods of screening for alcohol.
Can be used to detect the presence of alcohol with an estimate
to the degree of impairment. Being disposable, they are the most sanitary way of testing for alcohol. The disposable devices operate based on a known chemical reaction that is highly sensitive to alcohol and less sensitive to other gases. Unlike the semiconductor based sensors, the disposable devices are less likely to produce a false positive result. Being disposable makes these type of devices are the safest testers for the public and at much lesser cost than portable units.
Here's how the disposables work The ethyl alcohol in the blood escapes through the lung tissues into
the exhaled breath. The presence of ethyl alcohol in the breath
is detectable by a color change of very sensitive chemically coated
media contained encapsulated in these Disposable devices. Immediately
prior to use, the ampoule is ruptured by slight finger pressure
on the outer flexible and clear tube to release the crystals within the
confines of the ampoule. When the subject exhales into the tube, crystals
interact with breath vapor and change color from yellow to White/green blue (aqua)
if alcohol is present. If all the crystals change color completely from yellow to light blue or white to many eyes, it indicates that the subject's blood alcohol level is exceeding the tester's preset threshold level indicated on the tube.).02, .04, .05, or .08% BrAC.
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Urine Alcohol Testing |
Although urine alcohol testing will indicate the presence of alcohol in a person's body, it will not indicate an individual's current condition. Once consumed, alcohol enters the blood through the stomach wall within 15 minutes, causing immediate impairment. It is then metabolized by the liver enzyme and, after 1½ to 2 hours, it will begin to show up in the urine. Therefore, urine alcohol does not measure a true condition of the person. The results indicate the person's condition several hours before.
Additionally, urine alcohol concentration does not directly correspond to blood alcohol concentration. Urine alcohol concentration will vary depending on the person's metabolism and the amount of fluid in his system. For instance, a person who is slightly dehydrated will tend to have a higher alcohol concentration in his urine than someone who has a normal level of fluid in his system.
At least one study has indicated that a false positive for urine alcohol can occur. High levels of sugar and acetone in the body can cause fermentation in the urine, creating a false positive for urine alcohol. All things considered, the urine alcohol test is the least preferred or perhaps accurate test available for alcohol testing. It is worthwhile to read a supporting research paper published in THE AMERICAN JOURNAL OF CLINICAL PATHOLOGY: ERRORS OF CONVERTING A URINE ALCOHOL VALUE INTO A BLOOD ALCOHOL LEVEL. SIDNEY KAYE, PH.D., AND EDUARDO CARDONA, M. S. |
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