Quest found drug testing of hair specimens from employees and job applicants in the general U.S. workforce has tracked sharp downward trends in cocaine and methamphetamine use from 2005 to the first half of 2009 that mirror similar drops shown by urine testing. The data in the special report includes more than 27 million urine tests and more than 840 thousand hair tests performed by Quest Diagnostics.
Hair and urine test data show that declines in cocaine use have been dramatic since 2005, with hair tracking a 36 percent drop from 5.0 percent positivity to 3.2 percent positivity, and urine tracking a 57 percent drop from 0.70 percent positivity in 2005 to 0.30 percent positivity in the first half of 2009. A hair data decline of 55 percent in methamphetamine positivity rates, from 2.0 to 0.9 over the same period, validate the decline seen in urine test data, which fell 64 percent, from 0.28 to 0.10, said Quest officials in a statement.
Quest noted that while both hair and urine and tests showed a decline in drug use, the hair data revealed far more cocaine and methamphetamine use than urine alone. In the first half of 2009, the 3.2 percent cocaine positivity rate in hair testing is more than ten-fold that of the 0.30 percent positivity found in urine testing, and the 0.90 percent methamphetamine positivity rate in hair testing is nine times that of the 0.10 positivity found in urine. Overall drug use detected by hair testing during the same period reached 6.9 percent positivity; urine reached 4.2 percent.
"Hair has a longer memory than urine when it comes to finding patterns of drug use. That's because a drug test on a small amount of hair can detect a drug user's repeated consumption of a substance over time, while a test of a urine sample can signal drug use in the prior one to three days," according to Barry Sample, Ph.D., director of science and technology, Quest Diagnostics' Employer Solutions division. "Looking at hair and urine data from the same time period, and seeing both long-term repetitive use and recent use, gives us a more complex and sophisticated view of workforce drug habits."