Oral Fluid Drug Screening – The Detection of Drugs in the Workplace and on our Roadways

DETECTION AND MEASUREMENT OF DRUGS

INTRODUCTION

A great deal of  information is available regarding the true incidence and prevalence of illegal drug use in the workplace and on our roadways.  Breath-alcohol testing has established a scientifically sound basis for the estimation of the prevalence of alcohol use among reckless drivers (Dubowski, 1992), however,  ”drugged” drivers, especially the use of prescription drugs represent a serious safety threat.

Alcohol, prescription drugs and marijuana are the most prevalent issues affecting workplace safety, and most commonly abused substances on our roadways. Other drugs occurring with relatively high frequency are benzodiazepines, cocaine, various opiates and the amphetamines (e.g., MDMA, methamphetamine).

While many other drugs are found in injured or killed drivers, these five categories of drugs (i.e., cannabis, alcohol, and prescription drugs) appear to makeup the majority of the problem as currently understood.

Various technologies, especially oral fluid drug screens, have made available new devices for drug detection.

On-site drug and alcohol screens provide preliminary non-quantitative results, while  gas chromatography-mass spectrometry (GC/MS), and liquid chromatography-mass spectrometry delivery quantitative results typically recognized as acceptable practice for  court room situations.

A variety of specimens can be assayed for drugs, including urine, blood, sweat, saliva, and hair, among others.

Each specimen is unique, and each offers different patterns of information about drug use over time illustrates the general relationship between drug effects and the detection periods in various specimens. Each specimen has strengths and weaknesses about the level of information that can be gained about drug use.

State laws generally may or may not stipulate which specimens may be tested for drugs for criminal justice applications. (

Figure 3-1: Drug Detection Periods in Various Specimens

GENERAL METHODS AND SPECIMENS FOR DRUG SCREENING

Blood Testing

Blood testing is the true “gold standard”. However, due to the invasiveness of the collection procedure and the cost of laboratory analysis, routine screening of blood for drugs in typically impractical not used in the workplace or on the roadways.

Oral Fluid (Saliva) Testing

Oral Fluid / saliva screening is the most accessible matrix used for the detection of drugs, consists primarily of secretions from the submaxillary (65%), parotid (23%) and sublingual (4%) glands (Kintz, 1999). Detection times for drugs in oral fluids are roughly similar to that in blood, approximately up to 24 hours for marijuana and up to 48 hours for several other drugs.  Oral fluids normally contain the parent drug substance rather than drug metabolites such as are present in urine. Collection of oral fluid is far less invasive than either blood or urine, and is an excellent matrix to detect recent drug use.

Typically the analysis of oral fluids is collected on-site and may be initially screened via an on-site disposable device and then a sample is sent to a laboratory for confirmatory testing as required.

Sweat Testing

Drugs are excreted in the sweat mostly in the form of the parent compound. The collection of sweat over time can produce a cumulative record of prior drug use. Patches can be worn for periods up to several weeks, followed by removal, and sent to a laboratory for analysis. Sweat testing is not typically regarded as suitable for either workplace or roadside drug screening  due to the lengthy time required to produce a sufficient sample and the requirement for laboratory analysis.

Hair Testing

While the technology for assaying hair for drugs of abuse has progressed somewhat over the last 15 years, there remain many unresolved issues: for example, it is still unclear how drugs actually enter the hair. Because hair only grows at a rate of about one-half inch per month, it is not suitable for the detection of recent use.

Urinalysis

The drug testing methodology for urinalysis is well established, however, proven to be easily susceptible to persons defeating the process by specimen adulteration or substitution. Pre-employment workplace testing is the most common form of workplace drug testing, however, is not regarded as effective, but rather seen as an “IQ” test as drug abusers know when an where they they will be tested.  Primarily  drug metabolites are detectable in urine for several days after the drug has been used, however, recent drug use may be missed. While a positive urine test may represent “proof” of drug use within the last few days, it cannot be used by itself to prove recent or on-the-job” drug use, nor a relationship to behavioral impairment. While there are national standards for urine testing in place, they are out of date.  For example, they do not include the testing of commonly abused prescription drugs such as Oxycontin, Lortab, Vicodin, etc.

Characteristics of a Method to Detect and Measure Drugs in Body Fluids^a

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Characteristic	Definition
Sensitivity	The ability of a method to detect the presence of drugs or classes of drugs.
Speed	The time from start to end of the analytical process using a method.
Simplicity	Usually related to the speed of a method, the requirement for little training for technicians and often associated with highly automated procedures.
Reliability	The dependability of a method. Its ability to reproduce accurate and precise results day-to-day.
Accuarcy	The degree to which a method produces results consistent with actual values.
Precision	The consistency with which a method reproduces results when measuring the same sample.
Economy/Cost	Economic considerations include time of analysis, number of samples processed in a single run, degree of training required of personnel, price of obtaining (and maintaining) instrumentation, price of chemicals and other reagents used in analytical procedure, and overhead of analytical laboratory or other facility.
Safety	The degree to which personnel using a procedure are exposed to risk of injury or long-term toxicity associated with chemicals required by a method.
aAfter Joscelyn, Donelson, Jones et al. (1980)

Over the last 10 to 20 years the cost of using  technologies have become affordable, and many on-site device and  laboratories have the ability  to identify the most commonly used drugs.

Recent screening for drugged driving using on-site screening devices indicated up to a  36% positive rate for illegal drugs.

¹Epidemiologic literature on drugs other than alcohol is reviewed in Chapter 5

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