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Medical specimen containers
The U.S. Department of Transportation (DOT) is proposing a reform of drug testing programs for federal transportation workplaces. Instead of relying on urine samples alone, which can be tempered with and which strongly disadvantage workers who use legal marijuana in their personal time, the DOT is suggesting incorporating saliva testing as a faster, cheaper and more accurate alternative.
The Problem with Urine
Testing one’s ability to work through urine drug tests is customary, but urine testing has always been strongly discriminatory against marijuana users due to the unique window of detection of marijuana in urine compared with other substances. Amphetamines, methamphetamines, cocaine, opioids and phencyclidine (better known as PCP), which are the main drugs screened by DOT-regulated employers, all disappear from urine samples within four to nine days. Marijuana remains perceptible in urine for up to 67 days, according to the DOT themselves; but there have been cases where urine tests gave a false positive more than 90 days after the last ingestion of marijuana.
Marijuana is fat soluble, which means that marijuana particles bind themselves to fat cells. This is why making pastries infused with marijuana is such a popular way to consume the drug, as it attaches itself to common baking ingredients such as butter and oil. It also means that marijuana will remain longer in the body of a human being with a higher body fat percentage. Women typically retain marijuana longer, and so do people with a higher body mass index. Exercise can also release the tetrahydrocannabinol (THC, the psychoactive component of cannabis) retained in human cells; studies have found that someone whose urine tests negative can suddenly test positive for marijuana, despite not ingesting any in days or weeks, if they do as little as 35 minutes of exercise on a stationary bike before a urine test.
Marijuana is now legal in more states than not. But, as far as urine testing goes, personal and legal consumption of marijuana during one’s personal time is considered as bad as being high on the job. The psychoactive effects of marijuana only last between one hour (when smoking it) to half a day (when eating it). It is during that short window that one is actually under the influence, which means being dizzy, uncoordinated and decidedly unable to operate heavy machinery. In this regard, it is very similar to being drunk. But, unlike alcohol, marijuana continues to be picked up by drug tests for weeks and months after its psychoactive effects vanished.
Saliva Is a Superior Option
The first element put forth by the DOT is the cost of saliva testing, which is significantly cheaper than urine tests, as well as the elimination of the “shy bladder” problem. Saliva testing also reduces opportunities to cheat. But what matters most are the very different windows of detection.
All drugs test positive immediately or nearly so when tested orally. Methamphetamines and opioids are excellent illustrations of this: For 24 to 48 hours after ingestion of either substance, urine tests can give false negatives. The DOT’s own data reveals that meth and opioids are most likely to be detected in urine between two and four days after ingestion. If an employer is worried about the immediate ability of an employee to work or wants to determine whether an employee was under the influence of a drug after an incident occurred, a urine test might turn up negative even if the employee in question is currently high on meth. But that employee might test positive for marijuana for smoking a legal blunt on their own time three weeks earlier.
Saliva testing has a more immediate window of detection for every single drug screened by the DOT. It can detect substance use immediately after ingestion and is much less likely to give false positive results weeks or months after, unlike urine testing.
“Oral fluid testing for drugs of abuse offers significant advantages over urine as a test matrix. Collection can be performed under direct observation with reduced risk of adulteration and substitution. Unlike urine testing, there may be a close correspondence between drug and metabolite concentrations in oral fluid and in blood,” according to the primary study, led by the National Institutes of Health (NIH), which the DOT uses to support its suggestion to reform drug testing. The study finds a strong correlation between drug metabolites present in blood, which are what we are actively looking for to determine if someone is currently high, and their presence in saliva. “The frequently observed high correspondence of drug concentrations in oral fluid to blood makes oral fluid an attractive matrix for use in detection of recent drug use and in interpretation of possible drug-induced behavioral effects,” researchers conclude. The same is not true for urine testing.
The DOT had been considering testing saliva since 2004, the notice reveals, but the science was not up to the task yet at the time. “Since 2004, the scientific viability of that testing has advanced,” the DOT explains. “In its 2019 final rule, the Department of Health and Human Services stated that ‘the scientific basis for the use of oral fluid as an alternative specimen for drug testing has now been broadly established, and the advances in the use of oral fluid in detecting drugs have made it possible for this alternative specimen to be used in federal programs with the same level of confidence that has been applied to the use of urine.’”
It is a very positive thing that the Department of Transportation is seeking to amend drug testing rules that should have been corrected years ago; the DOT waited until the science was completely settled, which is perfectly fair. But the DOT is not the only employer out there. For the sake of employees and employers alike, especially in an America where cannabis is increasingly legal and commonplace, saliva testing should become the norm everywhere.