We recently received a letter from a reader who says he lost his job as a truck driver for a trash and recycling company where he had worked for more than two decades because he tested positive for cocaine in a random drug screen after inadvertently consuming some of his wife's coca tea. He notes that the Department of Transportation's drug testing guidelines (PDF) specify that "consumption of coca teas" should not be accepted "as a basis for verifying a cocaine test result as negative." Far be it from me to defend the ridiculous drug testing policies that have been foisted on employers by the federal government, which in this case (as in many others) led to a patently unfair result for an employee who posed no threat to anyone. But the rule regarding coca tea makes sense from a prohibitionist perspective.
According to a 1996 study reported in Forensic Science International, "the consumption of a single cup of Peruvian or Bolivian coca tea produces positive drug test results for cocaine metabolites." The reason is straightforward: Coca tea contains cocaine; coca is where cocaine comes from. So this is not, strictly speaking, a "false positive." Since coca leaf, like cocaine, is a Schedule II substance, coca tea is illegal in the United States, although you can buy it online and customs agents often let it through. It is not safe to assume that the leaf in these teas, like the leaf used to flavor Coca-Cola, has been "decocainized," and distributors are cagey on this point. For example, "pure powdered coca leaves" from Bolivia sold on Amazon are promoted as a "great coffee substitute" that is "caffeine free," an "energy booster" and "antidepressant" that "acts against fatigue" and is "excellent for diets" as an "appetite suppressant." But the only components of coca it mentions are "potassium, calcium, magnesium, iron, vitamins and all elements necessary in a daily diet." Hmm, what's missing from that list? Coca's stimulating, energizing, mood-lifting, appetite-suppressing effects do not come from potassium. The truck driver who wrote to us says the tea he drank, which his wife got from her mother, is available from brick-and-mortar stores as well as online, and the package says nothing about cocaine or even coca.
So if you have a job that requires drug testing, be careful about 100 percent natural, caffeine-free, yet mysteriously energizing tea from Peru or Bolivia. But if you are a customs agent, carry on as usual.