Last updated: November 27, 2023
Legalization proves that, overall, today’s society considers marijuana to be a harmless drug. However, that doesn’t change the fact that it remains illegal at the federal level. Many employers aren’t making any plans to remove the drug from the company drug test. Employees who don’t use the drug may worry about secondhand smoke—especially in those states that legalized recreational use.
They want to know if it’s going to make them test positive on the drug test.
Pot is more potent than ever
There’s no doubt that the potency levels are increasing as growers strive to produce the ultimate strain of marijuana. For them, of course, it all boils down to more money, but does it increase the potency of secondhand smoke as well?
The thought that those exposed to secondhand smoke could never ingest enough to cause a positive result on a drug test is long-standing. However, the increasing THC levels found in the drug made a study on the subject worthwhile.
The clinical study
The National Center for Biotechnology Information (NCBI) reported on a study that was conducted to see if secondhand smoke produced a level of THC that was high enough to cause a positive result on a drug test.
Six marijuana users volunteered for the study and six non-smokers agreed to participate as well. The test consisted of three sessions. In the first session, the marijuana used contained a THC level of 5.3%. In sessions two and three, they used marijuana containing a THC level of 11.3%.
The 12 participants sat together alternating a smoker and then non-smoker within a sealed chamber with no ventilation provided for sessions one and two. During the third session, they ventilated the chamber. The marijuana smokers lit up and after remaining in the chamber for a period of time, the non-smokers provided urine specimens for testing.
The participants provided 13 urine specimens over a 34 hour period.
Tests conducted using four immunoassays at different cutoff concentrations (20, 50, 75, and 100 ng/mL) showed no positive results at 100 and 75 ng/mL. Moreover, there was only one positive result at 50 ng/mL. Lastly, there were several positive results when tested at 20 ng/mL.
When they tested the non-smokers’ specimens using gas chromatography/mass spectrometry (GC/MS) they ranged from 1.3 to 57.5 ng/mL. The levels generally increased along with THC potency, however, room ventilation proved to substantially reduce the exposure levels.
A real-life scenario
The NCBI also reported on a study that corresponds with a situation that is far more likely to occur in real-life.
This study was conducted at a coffee shop in Maastricht, Netherlands.
A group of eight healthy volunteers who don’t use cannabis were exposed to the smoke for three hours in a well-attended coffee shop. Volunteers provided an initial urine sample before entering the shop.
Additional samples were obtained from the volunteers after their exposure to marijuana smoke.
The time markers were:
- 3 1/2 hours
- 6 hours
- 14 hours
- 36 hours
- 60 hours
- 84 hours
The samples underwent both the immunoassay and gas chromatography/mass spectrometry tests.
While the test results showed that all volunteers absorbed low levels of THC, none of the urine samples went above the standard cutoff concentration of 25 ng/mL.
In layman’s terms
So, while these studies provided documented proof that exposure to secondhand smoke does pose the risk of ingesting THC, it’s highly unlikely that one would inhale enough of the substance to cause a positive result on a urine drug test.
That said, though, the American Lung Association warned that even though there have been few studies done regarding marijuana smoke and overall lung health, all smoke contains toxins and carcinogens. Marijuana smoke contains many of the same toxins, irritants, and carcinogens as tobacco smoke.
Therefore, prolonged exposure to secondhand smoke could possibly result in lung damage.
Lastly, there’s a concern that children with consistent exposure to secondhand marijuana smoke could be more susceptible to health problems as a result.
We need more research
Marijuana legalization calls for further studies on how it affects the lungs—both those of users and those regularly exposed to secondhand smoke.
Studies show that marijuana smoke causes lung damage in those who chronically use the drug. It can result in causing chronic bronchitis. Moreover, evidence suggests that it can also injure the cell linings of the large airways. It might explain why chronic coughs, phlegm production, and wheezing often accompany long-term use of the drug.
However, whether or not those exposed to second-hand smoke could eventually suffer the same fate has yet to be determined.