Drug Testing vs. Drug Screening
Drug testing and drug screening are often used interchangeably, but actually mean slightly different things. Notably, drug tests tend to be more expensive and take longer to process than drug screens, but are also more accurate.
The terms “drug testing” and “drug screening,” are often used interchangeably but they are very different. A drug screen is a relatively inexpensive, quick method of scanning urine, blood, hair, saliva, etc.. Both a drug test and a drug screen look for the presence of drug metabolites, rather than the actual parent drug. When the body breaks down, or metabolizes a drug into a different substance, this is known as a drug metabolite.
What are Drug Metabolites?
When a drug metabolite is present, it can be reasonably deduced that a person used the parent drug of the metabolite. Some metabolites remain in the body significantly longer than the parent drug, meaning there is a higher probability of identifying a person that has used drugs by looking for metabolites rather than the original drug.
As an example, the active substance in marijuana is THC. When a person uses marijuana, the THC is quickly metabolized into several different metabolites that can stay in the body thirty days or longer following marijuana use. The metabolite benzoylecgonine occurs in those using cocaine.
This metabolite can show up in a blood or saliva test for up to two days after the last use, for up to three days after last use in a urine test, and for several months—or even years—in a hair test. Among those using cocaine frequently or in high doses, the body can take longer to eliminate the metabolites. Weight, whether the drug was mixed with alcohol, and individual metabolism also affect elimination time.
Drug Screens—Quick and Cheap
A drug screen is usually a quick screening that tests your urine for THC metabolites. The test is relatively accurate, and only costs employers about .95 cents per drug screen. The downside to these cheap drug screening tests is false positives. According to drugs.com, as many as 5-10 percent of positive drug screening results are inaccurate. This figure could actually be higher, as there is not widespread reporting on the issue.
When an initial drug screening test results in positive results, a second test should always be done, using a more accurate test, since a positive drug test can result in loss of employment, jail time, loss of privileges in a probation setting, and even inappropriate medical care. There are a number of over-the-counter drugs that can lead to a false positive drug screening. Included in this list are:
- Dextromethorphan, found in cough and cold products can lead to a false positive for narcotics, PCP, and angel dust.
- Sustiva, a prescription medication used to treat HIV infection symptoms, can cause a false positive THC result.
- Chronic use of NSAIDs like ibuprofen and naproxen can lead to a false positive test for barbiturates, THC, or PCP.
- Zoloft, a drug used for depression, can lead to a false positive result for benzodiazepines.
It is unlikely that passive marijuana smoke would cause a false-positive drug screen or drug test results, as the cut-off concentrations for lab analysis are set above those you could expect from passive inhalation.
Drug Testing—More Thorough, More Reliable, and More Expensive
A more detailed drug analysis is the drug test. Drug tests are much more involved than a drug screening. A drug test incorporates much more sophisticated equipment to confirm the presence of drug metabolites. A drug test is so accurate it can determine whether or not the urine sample is actually from a human. When a drug screening turns up positive, a drug test should be the follow-up. Our website has lots more information if you have questions regarding employment drug screening or testing.