SOFT - TIAFT 1998 Poster Session 4 Friday October 9, 1998

David A. Kidwell, Marsha A. Blanco*, and Janel C. Holland*

Naval Research Laboratory, Code 6170, Washington DC 20375, USA
* GeoCenters, Inc., Naval Research Laboratory, Washington, DC 20375, USA

Urine has been the favored testing medium for detecting and deterring drug use. However, the short window of detection for many drugs in urine coupled with the personal inconvenience in collection has led to the search for alternative matrices for analysis. We have shown that sweat, collected by a simple forehead wipe, can detect cocaine use/exposure at approximately twice the rate of hair analysis and much better than urinalysis for individuals in a drug treatment program. Likewise, in a randomly selected university population, sweat testing showed twice the rate for cocaine use/exposure than did hair analysis (Kidwell, et al. For. Sci. Int. 1997, 84:75-86). Using data from the first study, cocaine levels >15 ng/wipe appear to be indicative of cocaine use rather than exposure. A ratio of benzoylecgonine to cocaine of greater than 0.1 also appears to support use rather than exposure.

Although sweat testing is thought to measure both use and exposure, it still could provide useful information in driving under the influence cases. A positive sweat result, coupled with subjective observations of driving behavior and personnel demeanor, will provide powerful evidence to arrest a driver, impound the car, and conduct more extensive testing back at the station. To evaluate sweat wipes for detecting drug use/exposure in roadside testing, sweat wipes and saliva samples were collected from volunteer drivers who were not detained by officers for any alcohol, drug, or traffic violation at a special enforcement roadblock. In a separate collection, samples were also obtained from commercial truck drivers at an interstate weigh station. The saliva samples were analyzed by an enzymatic assay for alcohol and all had alcohol levels lower than 0.01%. Both the saliva samples and sweat wipes were analyzed by CI-GC/MS for cocaine and its metabolites, amphetamine class drugs, and opiates.

7-29% of the non-commercial drivers tested positive for cocaine (n = 182) whereas 1.5-6% of the commercial drivers were positive using 15 ng/wipe cocaine and 2.5 ng/wipe BE as the cut-off levels (n = 136). Approximately 1% of the saliva samples were positive for cocaine, demonstrating recent usage. The individuals with positive saliva samples also had the highest sweat positives. The saliva results indicate that individuals often do not show obvious signs of stimulant use.

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