There are a number of different bodily specimens that can be chemically tested to detect evidence of recent drug use. Although some state laws dictate which types of tests can be used, a number of options are technologically feasible. Urine is the most commonly used specimen for illicit drugs, reflecting SAMHSA’s guidelines, and breath is the most common for alcohol, reflecting DOT’s guidelines.
Results of a urine test show the presence or absence of drug metabolites in a person’s urine. Metabolites are drug residues that remain in the body for some time after the effects of a drug have worn off. It is important to note that a positive urine test does not necessarily mean a person was under the influence of drugs at the time of the test. Rather, it detects and measures use of a particular drug within the previous few days and has become the defacto evidence of current use. Because alcohol passes rapidly through the system, urine tests must be conducted very quickly after alcohol consumption in order to ensure any degree of accuracy. For this reason, urine tests are generally not helpful in detecting alcohol use as opposed to illicit and prescription drug use, which is more easily traced in urine.
A breath-alcohol test is the most common test for finding out how much alcohol is currently in the blood. The person being tested blows into a breath-alcohol device, and the results are given as a number, known as the Blood Alcohol Concentration (BAC), which shows the level of alcohol in the blood at the time the test was taken. BAC levels have been correlated with impairment, and the legal limit of 0.08 for driving has been set in all states.
Under DOT regulations, a BAC of 0.02 is high enough to stop someone from performing a safety-sensitive task for a specific amount of time (usually between 8 and 24 hours) and a BAC reading of 0.04 or higher is considered to be a positive drug test and requires immediate removal from safety-sensitive functions. Under DOT regulations, a person who tests at the 0.04 BAC level may not resume job duties until a specific return-to-duty process has been successfully completed. Other alternative specimens that can be used for detecting the use of selected drugs of abuse include blood, hair, oral fluids and sweat.
Analysis of hair provides a much longer “testing window,” giving a more complete drug-use history going back as far as 90 days. Like urine testing, hair testing does not provide evidence of current impairment, but rather only past use of a specific drug. Hair testing cannot be used to detect for alcohol use. Hair testing is the least invasive form of drug testing; therefore, privacy issues are decreased.
Oral fluids, collected from the mouth also can be used to detect traces of drugs and alcohol. Oral fluids are easy to collect (a swab of the inner cheek is the most common collection method), harder to adulterate or substitute, and may be better at detecting specific substances, including marijuana, cocaine and amphetamines/methamphetamines. Because drugs do not remain in oral fluids as long as they do in urine, this method shows promise in determining current use and impairment.
Determining the biological relationship between two people through DNA testing is simple, inexpensive, and more accurate than ever before. Along with paternity testing, DNA testing can prove or disprove relationships between siblings, grandparents, aunts, or uncles.
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