Many want to know how long illegal drugs stay in the system. I recently attended a seminar on illegal drugs in the workplace. The speaker mentioned that marijuana stays in the system for 30 days. He explained that this is so because marijuana is a fat-soluble substance that stays in the fat cells of the body. Well that may be true. But, most of the attendees assumed that a drug test for marijuana would likewise return a positive if tested within that 30 day period. Unfortunately that just is not an accurate assumption. A successful positive drug test depends on many factors. It depends on:
- the specific drug i.e. each drug has a different life span in the body,
- the detection window i.e. each drug has a different time frame in which the test can identify its presence in the body,
- the dosage i.e. a person consuming more concentrated amounts of the substance will be positive for a longer period of time than a person whose consumption concentration is not as high
- the frequency of use i.e. a person consuming an illegal substance once per day versus a person who consumes the illegal substance once per month
- cut-off levels i.e. the government has established cut-off levels for each type of drug. That means that if a drug test indicates the existence of an illegal drug in the system but it is below the cut-off level, the drug test is negative.
Quest Diagnostics has listed in a blog post the average detection windows for three different types of specimens.
In the blog post they report that urine specimen drug testing, the most commonly used testing method, detects drug use in the previous one to three days. Oral fluid specimen drug testing can detect recent drug use in the previous one to two days. Hair specimen drug testing can detect drug use as far back as 90 days.
However, an employer needs to be careful about using hair as a specimen for drug testing. In fact, referring to the seminar I recently attended, one of the attendees mentioned that their lawyers indicated that no action can be taken in court if a person tests positive for illegal drug use using hair as the specimen. There was some expressed alarm that this was so. There is a reason this is so. An employer can only take action against an applicant or an employee if that individual or employee is under “the current influence” of an illegal substance. Under the current influence means the drug test reveals the existence of an illegal drug in the person’s system. Under the current influence doesn’t mean the illegal drug was in their hair. That just means they ingested the drug sometime in the past. While hair testing can test illegal substance abuse as far back as 90 days, that doesn’t mean the individual is under “the current influence” of that illegal substance. And, in fact, the employer has been put on notice that the individual may be covered under the Americans with Disabilities Act as a potential recovering addict.
And, if as an employer you are using hair as a specimen. You must be aware of your state’s laws regarding the use of hair. For example, when it comes to hair testing, Maryland allows:
(3) (i) An employer who requires any person to be tested for job–related reasons for the use or abuse of any controlled dangerous substance may use hair derived from the human body as a specimen in accordance with this paragraph.
(ii) An employer may use hair derived from the human body only for pre–employment purposes.
(iii) If an employer uses hair derived from the human body as a specimen, the employer may not:
- Use a specimen that is longer than one and one–half inches measured from the human body; or
- Use the specimen for any purpose other than testing for controlled dangerous substances.
