There are several reasons why an individual is required to undergo drug testing. Examples of cases where a drug test is required or requested are:
- Random workplace
- Sporting events
- Insurance purchase
- Court ordered cases or when under suspicion by police to be DUI
Doctors may also perform drug tests to patients before their surgery or a critical medical procedure where there is a risk of medication reacting negatively with an illicit substance.
General definition and types of drug testing
A drug test is when a urine, saliva, blood, or hair sample is evaluated in order to determine if a person is using or has prior used a specific drug by looking for the drugs or drug metabolites present in the sample.
A urinalysis or urine test is the most common especially for pre-employment and workplace purposes. This test seeks to detect the presence of a drug’s metabolites in urine. An example is the THC-COOH marijuana metabolite, which can be present in urine for one to two weeks. While urine testing is the most common drug testing method, it is also known to be the easiest to beat.
The saliva or swab test is another popular drug test method especially for random testing: it is less invasive than a urine test, less expensive than a blood test, difficult to tamper with, can be administered at any place and time, and can produce instantaneous results. Saliva drug testing can detect cocaine, marijuana, opiates, and phencyclidine use.
However, saliva drug testing has an inherent limitation because only small amounts of a drug are released into a person’s saliva. This means that only those that were taken no more than 48 hours prior to testing can be detected. Thus, a drug test via saliva sample is generally administered to test for recent use.
- Blood Test
The blood test is the most accurate form of drug testing. It can actually detect the presence of drugs and not just the metabolites, as drugs are instantly absorbed into the bloodstream. While accurate, it is also the most invasive and most expensive compared to the other types, which is why it is rarely used for employment purposes. Blood testing is also accurate only for recent use because drug toxins can only be found in blood up to 48 hours, unless it is a blood sample from a chronic user.
Drug testing via blood sample is typically done when the law is involved such as in accidents where DUI is suspected, wherein a blood test can indicate more accurately if an individual is under the influence at the time when the blood sample was taken.
- Hair Follicle
Hair tests do not measure current drug use; rather they are used to determine if there is a pattern of usage by detecting the presence of metabolites in the hair follicles. For example, if an individual uses a drug, abstained for some time, and then used it again, testing that person’s hair will reveal the pattern because drug metabolites get stored in hair as it grows and this cannot be removed. In the absence of hair on a person’s head, the hair from the nape of the neck is used. This test is also expensive and is often used only when required by law to confirm other previous tests, or with job positions that require more comprehensive drug testing.
Accuracy of drug testing
If done properly, a drug test will provide accurate results. Accuracy of results depends on several factors such as how the specimen was collected, when it was collected, and if the test was random or not. There should be no chance of contamination or tampering of the specimen, the test should be conducted within the drug’s window of detection, and if possible the subject should have no prior knowledge for a higher accuracy rate.