The percentage of American workers testing positive for illicit drugs such as marijuana, cocaine, and methamphetamine has increased for the second consecutive year in the general US workforce, according to insights from more than 10 million workplace drug test results recently released by Quest Diagnostics, Madison, NJ. The analysis suggests a potential reversal in the decades’ long decline in the abuse of illicit drugs in the US workforce.

The Quest Diagnostics Drug Testing Index (DTI) shows that the positivity rate for approximately 6.6 million urine drug tests in the general US workforce increased overall by 9.3%, to 4.7% in 2014 compared to 4.3% in 2013. Analysts noted that 2013 was the first year since 2003 in which the overall positivity rate for urine drug tests increased in the general US workforce. In addition, overall positivity for oral fluid and hair drug tests, representing approximately 1.1 million tests, increased between 2013 and 2014 in the general US workforce.


Barry Sample, PhD, Quest Diagnostics.

“American workers are increasingly testing positive for workforce drug use across almost all workforce categories and drug test specimen types,” says Barry Sample, PhD, director of science and technology at Quest Diagnostics Employer Solutions. “In the past, we have noted increases in prescription drug positivity rates, but now it seems illicit drug use may be on the rise, according to our data. These findings are especially concerning because they suggest that the recent focus on illicit marijuana use may be too narrow, and that other dangerous drugs are potentially making a comeback.”

“The increases in illicit drug positivity in employment drug testing should get employers and policymakers to take notice of the serious risks these drugs create for productivity, health, and safety,” says Robert DuPont, MD, former director of the National Institute on Drug Abuse (NIDA). “Many of these substances are clearly associated with impaired physical and cognitive functions. This analysis by Quest Diagnostics suggests that illicit drug use among workers is increasing broadly for the first time in years in the United States. Public and private employers might want to consider revisiting existing substance abuse policies to ensure that they are taking the necessary precautions to protect their workplace, employees, and businesses.”


Robert DuPont, MD.

The DTI analyzed urine, oral fluid, and hair drug tests performed by Quest Diagnostics workplace drug testing laboratories across the United States in 2014. Test results are examined according to three categories of workers: employees with private companies (general US workforce); employees subject to federal drug testing rules, including safety-sensitive employees such as truck drivers, train operators, airline employees, and nuclear power plant workers (federally-mandated, safety-sensitive workforce); and a combination of both groups (combined US workforce). Quest Diagnostics has analyzed annual workplace drug testing data since 1988.


Marijuana continues to be the most commonly detected illicit drug, according to the DTI. Marijuana positivity in the general US workforce increased 14.3% (2.4% in 2014 vs. 2.1% in 2013). By comparison, marijuana positivity in the same workforce category increased 5% between 2012 and 2013. In the safety-sensitive workforce, marijuana positivity increased 6% (0.71% vs. 0.67%) between 2013 and 2014, compared to 5.6% between 2012 and 2013. The steady increase in the marijuana positivity rate is consistent with findings from other data sources, such as the National Survey of Drug Use and Health (NSDUH).

Quest researchers also analyzed urine drug test data for the US workforce from two states with recreational marijuana-use laws. In Colorado and Washington, the marijuana positivity rate increased 14% (2.62% vs. 2.30%) and 16% (2.75% vs. 2.38%), respectively, in the general US workforce between 2013 and 2014, roughly parallel to the national average of 14.3%. By comparison, the marijuana positivity rate increased 20% and 23% in Colorado and Washington, respectively, in the general US workforce between 2012 and 2013, compared to the national average of 5%.

“We were surprised that marijuana positivity increased at about the same rate in Colorado and Washington as the rest of the United States in 2014, particularly given the sharp increases in the marijuana positivity rate in both of these states in the prior year,” says Sample. “It’s unclear if this data suggest a leveling off in marijuana use in these particular states or if some other factor is at work. We also find it notable that the national marijuana positivity rate increased as much as it did in 2014, and question if this means that people are more accepting and therefore more likely to use marijuana recreationally or for therapeutic purposes than in the past, even in states where marijuana’s use is not clearly sanctioned by state laws. This will be an important area of continued analysis given the national debate about the legality and health impacts of recreational and medicinal marijuana use.”


The DTI analysis showed steady increases in workplace positivity for cocaine in the general US workforce over the past 2 years, reversing a prolonged period of decline. The positivity rate for cocaine in urine tests increased by 9.1% (0.24% vs. 0.22%) between 2013 and 2014. Urine drug tests account for the vast majority of cocaine drug tests. The positivity rate also increased in oral fluid and hair specimens, by 30.6% and 13.0%, respectively, year over year.


Continuing a multiyear upward trend, amphetamines use—specifically the use of methamphetamine—showed an increase across both urine and oral fluid drug tests.

General US workforce data in urine drug tests showed a 7.2% year-over-year increase in amphetamines positivity in 2014 compared to 2013 (1.04% vs. 0.97%). In the general US workforce, methamphetamine positivity in urine drug tests increased 21.4% (0.17% vs. 0.14%); the positivity rate for oral fluid methamphetamine tests increased 37.5% (0.33% vs. 0.24%). Across all specimen types, the positivity rate for amphetamines is now at its highest levels on record and the positivity rate for methamphetamine is at its highest level since 2007.

Amphetamines describe the category, or drug class, that includes both prescription amphetamine drugs like Adderall and methamphetamine, an illicit drug often known for being produced in clandestine labs. They are a class of central nervous system stimulants that cause increased energy and alertness followed by exhaustion as the effects wear off.

The positivity rate for 6-acetylmorphine, or 6-AM, a specific marker for heroin, doubled in the general US workforce between 2011 and 2014 (to 0.031% in 2014 vs. 0.015% in 2011).

“Our DTI data mirrors research from the National Drug Intelligence Center which also shows that heroin use has increased markedly in recent years. While overall prevalence is low, the escalation in the detection of the 6-AM metabolite indicates heroin use may be growing,” says Sample. “With the high costs associated with prescription opiates, some drug users may be turning to comparatively cheaper alternatives like heroin.”

The strengths of the DTI analysis include its large sample size, the longitudinal nature of the monitoring, a testing population that is generally reflective of the US workforce and the quality of the company’s drug testing services to confirm positive results. Limitations include the selection of the testing population, which is reflective only of results from employers that perform drug testing and a lack of exact cross-specimen comparisons due to variations in substances for which employers test. DTI reports involve analysis of deidentified results from urine, oral fluid, and hair drug tests.

For more information about the DTI, including comprehensive data from the present report, visit Quest Diagnostics.