women smoking marijuana

By Jill Erickson, contributing reporter

Passive smoking or second hand smoke means that the person who is not smoking will still have trace amounts of the active drug ingredients and metabolites in their system. This could be detected on a drug test (blood test), but in most cases marijuana testing involves a urine sample. It is unlikely that the average marijuana urine test will be able to pick up these trace amounts of the active ingredient tetrahydrocannabinol (THC) and its metabolites.

However, it is not impossible as newer tests are becoming more sensitive. It is also possible that if you have the test within a few hours to a day jillericsonheadshotafter being exposed to marijuana, it may test positive but once again this is unlikely by traditional testing methods these days.

Every drug screening test has cut-off concentrations where it will not test positive for amounts lower than these cut-off amounts. For marijuana urine tests, the cut-off concentration is usually about 50ng/ml. Most passive smokers will not inhale or absorb enough THC for the metabolites to register at these levels in a urine test. But it also depends on what type of environment you were in during exposure to marijuana smoke and over how long you were exposed.

If you have not smoked any marijuana and if your test does return with a positive result, you could make an appeal and have a blood test or repeat the urine test. In most cases, the result of a single urine test on the first screening will not be considered as conclusive for the presence of the active ingredient and metabolites and confirmatory testing will usually be done. However this may vary in terms of individual organizations and their drug use policy.

For more on drug testing read our investigative report.