People have to take drug tests for all types of reasons. The most likely reasons are either for employment purposes or because it is court ordered. Regardless of the reason as to why a drug test must be taken, if you are a cannabis consumer facing a drug test, you are likely freaking out. The best way to pass a drug test when you are a marijuana consumer is to refrain from use for as long as possible prior to taking the test.
But even people that don’t directly consume marijuana need to be careful when taking a drug test if they have been around other people consuming marijuana. I know that when I was growing up I falsely believed that as long as I wasn’t inhaling straight from the joint or pipe, that I would be able to pass a drug test with no problems. I would also try to calm my friends that were sitting in a ‘hot box’ with me and other friends, trying to quell their fears about a looming drug test that they may be subjected to.
It turns out that if you are exposed to secondhand marijuana smoke, you run the risk of failing a drug test. It’s not automatic, but the more exposure to secondhand marijuana smoke the greater the chance of failing a drug test. I used to wonder if it was a myth or if there was actual scientific proof that someone could fail a drug test because of secondhand marijuana smoke, but a study from 2015 cleared things up. Per the study:
Non-cannabis-using individuals were exposed to secondhand cannabis smoke from six individuals smoking cannabis (11.3% THC) ad libitum in a specially constructed chamber for 1 h. Chamber ventilation was experimentally manipulated so that participants were exposed under unventilated conditions or with ventilation at a rate of 11 air exchanges/h. Physiological, subjective and behavioral/cognitive measures of cannabis exposure assessed after exposure sessions were compared to baseline measures.
Exposure to secondhand cannabis smoke under unventilated conditions produced detectable cannabinoid levels in blood and urine, minor increases in heart rate, mild to moderate self-reported sedative drug effects, and impaired performance on the digit symbol substitution task (DSST). One urine specimen tested positive at using a 50 ng/ml cut-off and several specimens were positive at 20 ng/ml. Exposure under ventilated conditions resulted in much lower blood cannabinoid levels, and did not produce sedative drug effects, impairments in performance, or positive urine screen results.
Room ventilation has a pronounced effect on exposure to secondhand cannabis smoke. Under extreme, unventilated conditions, secondhand cannabis smoke exposure can produce detectable levels of THC in blood and urine, minor physiological and subjective drug effects, and minor impairment on a task requiring psychomotor ability and working memory.
As you can see from the results of the study, being around people smoking marijuana can result in a failed drug test. Most of the subjects of the study were not above the standard 50 ng/mL, which is the threshold for most drug tests when it comes to marijuana (although some differ). But at least one person was above that threshold.
If you are facing a drug test in the near future, you may want to reconsider sitting in a poorly ventilated area where your friends and/or family are smoking. It seems like room ventilation goes a long ways towards addressing the issue, so if you are around people smoking on a back porch you shouldn’t be too worried. But always remember that THC metabolites stay in your system for a long time, and if you have a drug test coming up for a job or other important reason, proceed accordingly.