You’ve received the results from your company’s latest random drug screenings, and your best employee tested positive for marijuana. In their dispute of the results, they say it’s because they went to a music festival recently and were surrounded by smokers. Is their answer plausible?

Recreational marijuana use is now legal in 10 states, plus Washington, D.C. As more states begin to legalize some form of marijuana use, concern grows that secondhand exposure to the drug can cause a positive test. Many people believe that the indirect ingestion of delta-9-tetrahydrocannabinol or THC, the psychoactive substance in cannabis that produces the high. However, this belief is just a myth.    

According to Dr. Barry Sample, Senior Director of Science & Technology at Quest Diagnostics, there are no published or peer-reviewed studies to indicate that inhaling THC secondhand will lead to failed drug screenings. His findings are echoed by the National Institute on Drug Abuse (NIDA) in a study on secondhand exposure that measured the potency of different strains, length of time exposed, and ventilation of the smoking area. NIDA’s research also found that positive screens for marijuana from contact highs were extremely improbable. If THC is present in the drug test results, it is almost certainly because cannabis products were directly inhaled or ingested by the individual.

While your employee has a creative response to their drug test results, the research shows their explanation won’t stand up to scrutiny.

Employers should continue to monitor state and federal laws regarding the legality of marijuana use, especially as drug positivity rates rise in the United States. Click here to learn more about marijuana use from Quest Diagnostics, or contact us to evaluate your drug testing options with ESS at solutions@es2.com.