A new report by the American Transportation Research Institute (ATRI) is raising concerns that current approaches to drug testing and the spreading legalization of marijuana in the U.S. are contributing to the shortage of truck drivers.
Twenty-three states now legalize recreational marijuana, up from 10 in 2019. That means 41.4% of American truck drivers now live in the legalized jurisdictions, up 18.5% during the same period, ATRI notes in its Impacts of Marijuana Legislation on the Trucking Industry report.
But federal regulations do not allow CDL holders to use marijuana, identifying it as a Schedule 1 drug.
Over half (57.2%) of all positive drug tests in the trucking industry are for marijuana, ATRI says, citing Federal Motor Carrier Safety Administration (FMCSA) Drug and Alcohol Clearinghouse (DACH) data. More than 100,000 drivers were suspended because of failed tests between 2020 and 2022 – a frightening dynamic amid the national truck driver shortage.
CDL holders who work in the U.S. are subjected to random, pre-employment and post-accidental testing, as well as reasonable suspicion and return-to-duty drug testing, usually performed through a urine test.
Positive tests vs. impairment
Unlike alcohol testing, where the traces of alcohol are not noticeable for days or even hours after consumption, marijuana can still be detected for up to 30 days after consumption, increasing the likelihood of positive tests.
However, a positive test does not indicate the trucker was driving impaired, unless the test was conducted hours after an accident. (One of the studies that ATRI analyzed in its report suggested that drivers should wait five hours after inhaling marijuana before operating any vehicle.)
And there is no marijuana impairment test.
“While current marijuana testing is likely effective at removing drivers who may work while impaired, it also likely removes drivers who previously used the drug but would not operate a truck while impaired,” ATRI concluded. “This fact has led to the removal of many thousands of drivers from the industry based solely on past marijuana use.”
Looking for a better test
For that reason, the majority (65%) of carriers and drivers surveyed by ATRI have indicated they would prefer an industry-wide shift toward a test that indicates recent marijuana use (for example, the day before), instead of the current test that can identify earlier marijuana use.
“Testing impaired individuals through a quantitative measurement – which has been key to combatting drunk driving – remains elusive in the case of marijuana. There is not even a definition or quantitative threshold for marijuana impairment,” ATRI’s study says.
According to ATRI, while the industry’s current approach does support safety, it also proves to be inefficient when drivers who do not present a safety issue are removed from their duties.
The institute is calling for a nationally recognized marijuana impairment tool, an accepted threshold that would indicate impairment, and further federal research into the drug’s impact on highway safety.
Existing research indicates the drug affects driving-related cognitive skills, decision-making, and reaction times, and some data has identified an increase in non-fatal crashes and collisions after legalization. But ATRI wants further federal research into the issues to close the knowledge gaps.
Prohibiting marijuana use outright was identified as a “potential disincentive” for truckers to stay in the industry. But the report notes there’s still a debate about whether restrictions should be loosened or remain in place. Each choice would present challenges for the industry.
If marijuana remains a federally prohibited drug, more drivers will be removed from their duties. Some will leave for other jobs where there is no mandatory testing.
For example, over half of the truckers who were prohibited from driving because of failed drug tests between 2020 and 2022 have shown no desire to return to their trucking duties.
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