shutterstock_181507925The Yahoo/Marist Poll released in April 2017 reveals how attitudes and behaviors towards marijuana are changing among Americans. Interestingly, more adults now think “marijuana is less unhealthy than Miller High Life or Marlboros.” 29 US states and the District of Columbia have some form of legalized marijuana legislation. Our neighbors up north are going even further. Prime Minister Trudeau unveiled a bill legalizing recreational marijuana in Canada as soon as mid-2018. Along with these changing attitudes, there are growing pains with mitigating the negative impact of legalized marijuana and ensuring public safety. Concerns include appropriate forensic tests for determining THC (delta-9-tetrahydrocannabinol) levels in biological samples, and impaired driving under the influence of marijuana (DUID). States are worried that marijuana use will contribute to and increase DUID fatalities.

THC is the main psychoactive cannabinoid in cannabis. Blood and urine levels of THC and its metabolites do not manifest themselves consistently in all users. Typically, new or infrequent users quickly metabolize THC, while regular or chronic users may have low levels on board for as long as 30 days after last use, long after acute impairment. This makes cannabinoid data interpretation difficult for determining probable cause.

For DUID cases, blood is a common biological fluid tested. THC and other cannabinoids detected in blood can indicate recent use and acute impairment. Urine, on the other hand, is more often analyzed for pre-employment or compliance drug testing. Metabolites of THC such as 11-nor-9-carboxy-THC (THC-COOH) are routinely quantified in urine to determine prior marijuana use as far back as approximately 30 days. Hair THC testing is useful for documenting specific times of use over past weeks or even months. Unfortunately, blood and urine drug testing are invasive and time-consuming. Blood collection requires trained medical personnel for sample collection, which may occur up to 4 hours after the time of a crash or DUID traffic stop.

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Oral fluid and exhaled breath have been progressing in the past few years as viable sample matrices for drugs of abuse testing. These alternative matrices address the complications of blood testing with easier access to specimen, rapid and convenient collection on site, and without the need for medical professionals. Olof Beck at the Karolinska Institute first published on breath drug testing in 2010, concluding that drug intake can be detected in exhaled breath after sampling on filter paper. Marilyn Huestis from the National Institute on Drug Abuse presented recent progress on THC testing with oral fluid at the 2016 SOFT conference.

When alternative matrices such as oral fluid and breath were initially proposed, few analytical methods were sensitive enough to quantify THC and metabolites down to low ng/mL levels. However, state-of-the-art analytical instruments such as high-resolution accurate mass spectrometry (HRAM), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) have provided exceptional performance and the necessary sensitivity to detect and quantify THC, other cannabinoids and metabolites down to pg/mL levels. Work is progressing on marijuana testing to advance the ability of forensic labs to determine THC levels and better interpret cannabinoid data. The goals are to provide expedient sample collection to account for variable THC metabolism, and to identify a combination of analytes that have short windows of detection and, therefore correlate better with recent use.

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