The Use of Oral Fluid and Sweat Wipes for the
Detection of Drugs of Abuse in Drivers*
Nele Samyn,1 Pharm.; Gert De Boeck,1 Ph.D. and Alain G. Verstraete,2 M.D.
J Forensic Sci, Nov. 2002, Vol. 47, No. 6
Paper ID JFS2002003_476
Available online at:
www.astm.org
ABSTRACT: Blood, urine, oral fluid (by spitting or with a Salivette®), and sweat samples (by wiping the forehead with a fleece moistened with isopropanol) were obtained from 180 drivers who failed the field sobriety tests at police roadblocks. With quantitative GC-MS, the positive predictive value of oral fluid was 98, 92, and 90% for amphetamines, cocaine, and cannabis respectively. The prevalence of opiate positives was low. The SAMHSA cut-off values for oral fluid testing at the workplace, proved their usefulness in this study. The positive predictive value of sweat wipe analysis with GC-MS was over 90% for cocaine and amphetamines and 80% for cannabis. The accuracy of Drugwipe® was assessed by comparing the electronic read-out values obtained on-site after wiping the tongue and the forehead, with the corresponding GC-MS results in plasma, oral fluid, and sweat. The accuracy was always less than 90% except for the amphetamine-group in sweat.
In March 1999, the Belgian parliament adopted a law on driving under the influence of certain illicit drugs. A driver is sanctioned if _9-tetrahydrocannabinol (THC), cocaine, benzoylecgonine, morphine, amphetamine, 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA) or N-methyl-1-(3,4 methylene-dioxyphenyl)-2-butanamine (MBDB) are detected in plasma in concentrations higher than the analytical cut-off values mentioned in the law (1). Similar “per se” laws were introduced in Germany in 1998 and in Sweden in 1999 (2,3).
In Belgium, an initial suspicion of impairment is established using a drug recognition test battery, based on external signs of substance abuse and on some well-defined psychomotor tests, followed by a urine screening test. One of the key elements in the enforcement process is the possibility to perform screening tests rapidly at the roadside, to take immediate administrative measures (disqualification from driving for minimum 6 h) and to select drivers for blood sampling. As for drug screening at the workplace, oral fluid and sweat testing offer a non-invasive way of screening at the roadside and hence the possibility of direct supervision of sampling.
This is a major advantage in comparison to urine testing (4–6). In Belgium, police officers are eager to participate in the evaluation of on-site tests for screening of oral fluid and sweat. Since oral fluid sampling can be time consuming because of a decrease in salivary flow after amphetamine use or cannabis smoking, and the high viscosity of the collected specimen, an on-site test should only require a small volume of sample. The sampling procedure with the Drugwipe® is very simple as it consists of wiping the tongue or some part of the skin e.g., the forehead (7). Orasure Technologies (Bethlehem, PA, USA) have obtained FDA approval for the screening of a panel of drugs of abuse in oral fluid using the Intercept Micro-Plate EIA, but this is a laboratory-based technique. However, very recently, the same company received FDA clearance for their oral fluid pointof- care test for opiates (UPlink®). Oral fluid analysis is considered as the main alternative to blood to document recent use of medicines or drugs of abuse. Some drugs might have a larger detection window in oral fluid than in blood e.g., weakly basic drugs, smoked drugs (4,8). However, the collection protocol and the route of administration significantly influence the concentrations detected in an oral fluid sample (4,8,9).
The time window when the drug is expected to arrive on the surface of the skin is very broad (5,10), but in most cases, drugs will appear later in sweat than in oral fluid. Because of the longer delay of appearance of drugs in sweat, it seems more difficult to use a sweat test to indicate recent drug consumption. However, as an indication of relatively recent drug abuse and in addition to the drug recognition test battery, sweat testing might be useful in a driving under the influence of drugs (DUID) situation (11). During this study, newly trained police officers evaluated drivers at special enforcement roadblocks. For 180 and 135 subjects, respectively, oral fluid and sweat samples were quantitatively analyzed and compared to the corresponding plasma and, if available, urine laboratory results. The reliability of Drugwipe® is assessed by comparing its on-site results with confirmatory GC-MS results in plasma, oral fluid, and sweat.....
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