Alcohol is the most commonly used drug in the world. Alcohol in small amounts induces a feeling of mild euphoria but as volume increases, inhibitions, mobility, decision making and coordination decreases with stupor and unconsciousness occurring with high dosages. Alcohol also has a synergistic effect when accompanied with use of other drugs like cannabis, barbiturates and cocaine, increasing the potency of the effect.
Law enforcement is thus concerned about public inebriation, especially when driving vehicles and in the conduct of crime. Alcohol tests may be ordered when a person is observed by law enforcement officials to be exhibiting loss of coordination, slow reaction time, vomiting, and unconsciousness or if physical appearance and demeanor indicates inebriation. Alcohol levels in a person’s body indicate the amount of alcohol consumed within a certain time frame.
There are various methods used to determine alcohol content in a person’s body, usually using a person’ breath, saliva, blood and urine. Among the different tests available to determine alcohol levels in a person’s body, urine testing is among the most reliable and the most flexible in terms of detecting for additional substances and it is the most inexpensive. However, urine testing is usually the easiest to fake, one of the most invasive and one that poses a biohazard to the tester. Urine testing also just measures the presence of alcohol ingested up to 48 hours prior, however, since alcohol takes one half to two hours to be metabolized, urine tests does not accurately predict a person’s current alcohol consumption. Urine tests are also dependent on a person’s physical status, with dilution, metabolism and other factors playing a role in the results. The presence of glucose as well as some microorganisms in the sample could also lead to higher ethanol counts since glucose can be fermented with time and sufficient temperature.
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Urine testing involves looking at a sample’s ethanol content to determine a person’s alcohol intake. Drinking alcohol or ethanol is broken down in the liver to acetaldehyde via the enzyme alcohol dehydrogenase. Acetaldehyde is in turn broken down into acetic acid as well as to other by products. Another pathway that breaks down ethanol is the cytochrome P450 2e1 pathway that breaks down ethanol to acetaldehyde and other reactive radicals. Urine testing utilizes the alcohol dehydrogenase pathway to determine alcohol in urine. This method, the alcohol dehydrogenase assay, measures the reduction of nicotinamide adenine dinucleotide to measure the amount of ethanol present in the sample.
Another, more sensitive test for alcohol in urine is the EtG test. Etg or ethyl glucoronide is another by product of alcohol metabolism. Unlike ethanol, EtG stays in the body up to 80 days, making it a useful alcohol detection method for alcohol consumption in the military and in schools. However, the sensitivity of ethyl gluoronide makes false positive an easy occurrence. Many household products, like hand sanitizers, detergents, and even antiperspirants contain alcohol. It is thus easy to trigger a positive just by moderate usage of alcohol containing products. This means that EtG tests by itself is viewed somewhat unreliable and may require corroborating results from other tests.
In converting urine test results to alcohol blood content, the assumption is usually that 1.3 parts of alcohol present in the urine equals one part present in alcohol. However, this value can vary greatly among individuals creating a source of error.
Urine testing lags behind blood testing in terms of accuracy of results. However, it still is a commonly used detection tool. Although relatively easy to fool with dilution and has numerous sources of error, it still used by law enforcement and is quite capable of withstanding legal challenge.[ad#afterpost]
- Advanced Safety Devices Alcohol Testing Methodology obtained from http://www.safety-devices.com/alcohol-testing-methodology.htm
- Buddy T. (2008) Widely-Use EtG Test for Alcohol Unreliable obtained from http://alcoholism.about.com/od/work/a/etg.htm
- Worthington Biochemical Corporation from A Vallee and Hoch (1955) Alcohol dehydrogenase assay obtained from http://www.worthington-biochem.com/ADH/assay.html