Percentage of Amphetamines and Opiates in
Positive Employee Drug Tests Increases

Of the more than 7.1 million workplace drug tests conducted by Quest Diagnostics in 2003, 4.5%
tested positive for at least one illicit drug, a rate that has remained relatively constant since 1999.
However, there has been a shift in the types of drugs detected. The percentage of positive drug tests
containing amphetamines doubled, from 4.5% in 1999 to 9.3% in 2003, primarily due to an increase
in methamphetamine positives. The percentage of positive drug tests containing opiates, particularly
methadone, propoxyphene (e.g. Darvon®), and morphine, also increased during this period, from
7.5% to 12.3% of all positive tests. In contrast, the percentage of positive tests that contained
marijuana and cocaine decreased from 1999 to 2003.

*The category “opiates” includes methadone, propoxyphene, and other opiates. The category “other” includes
barbiturates, benzodiazepines, PCP, acid/base, oxidizing adulterants, and substituted urines.

NOTES:
This data is from workers employed by companies that use Quest Diagnostics’ drug testing services, including
federally-mandated safety-sensitive workers. Reasons for testing include pre-employment, periodic, random,
post-accident, for cause, and returned to duty.

SOURCES:
Center for Substance Abuse Research – University of Maryland , College Park
A complete list of sources is available at www.cesar.umd.edu.
Available from Quest Diagnotics online at http://www.questdiagnostics.com/employersolutions/dti_07_2004/dti_index.html.