Problems of Urine Screening

Morgan, John, "Problems of Urine Screening." Journal of Psychoactive Drugs. 1984; 16(4): pp. 305-317.

Introduction In 1984, a careful study under field conditions by Kleinmutz and Szucko called into question the ability of the polygraph and its interpreters to detect lies: "...our findings show high false-positive and false-negative rates among polygraph interpreters.... we conclude that the validity and reliability of polygraphic interrogation has yet to be established." It is doubtful that this critical study will eliminate the use of the lie detector. Its presence, however technically flawed, has great symbolic utility. Its application satisfies the powerful desire to know intimate and hidden details of the moral behavior of humans.

The desire to know about secret drug use may be nearly as compelling as the wish to discern lying. A commitment to drug detection technology is developing in a similarly uncritical fashion.

There are widely accepted justifications for drug testing. Individuals in treatment or probationary programs may be required to submit to urine monitoring as evidence of their commitment to the program, which they even may have joined to avoid incarceration. Individuals in the workplace who have been involved in accidents are sometimes subjected to mandatory testing. The desire to know if a motorman caused an accident because of careless drug use is understandable and corresponds to assessing ethanol concentration in those involved in nonwork-related vehicular accidents.

None of these preceding categories anticipates the mass screening of overtly functional people who, because of employment, military or prisoner status, are subjected to mandates to offer up their urine for drug testing. Not only is this a new phenomenon, but it places the drug-positive individual in the grim situation of proving his/her innocence - not of intoxicated dysfunction or malfeasance, but of immoral and undesirable behavior. The usual justifications offered for mass screening do not withstand examination.

These proceedings contain a number of references to the cost of drug abuse to American industry (e.g., Cohen 1983). Most of these estimates are extrapolations and projections that have no convincing data base. The cost estimates are derived from a set of seldom questioned but surely questionable assumptions. These include the belief that dysfunctional work (or life) and a history of use or presence of a drug are causally associated, and the assumption that all who use drugs are sure and soon to malfunction in a fashion similar to the drug abusers seen in treatment programs.

These assumptions are pervasive and are often stated to justify compulsive monitoring on the grounds of imminent danger to the user or other workers, lapses in security or the need to detect drug use in order to intervene with treatment. Such justifications are part of the operational process of "medicalization" of ethical and political conflicts. Medicalization increases the options of controlling conflicts and problems without protest because there is little argument possible against medical language, predefined as humane (Roman 1980). In truth, these excuses are weak for two important reasons. There is almost no proven correlation between any positive urinary test for drugs and observed or assessed human behavior. The tests that assess the drugs of most current interest (marijuana and cocaine) measure metabolites of the drug that persist for hours or days after use. Therefore, any positive test cannot be used in an assessment of work-related dysfunction because it might well reflect recreational or even work-related use well in the past. Moreover, the descriptions of supposed malfunction all ignore an experimental and anecdotal history of drug use that improves work performance. Both ancient Peruvian miners (Helms 1975) and modern

Jamaican workers (Rubin & Comitas 1975) have been characterized as working better under drug influence. A variety of studies have indicated that stimulant drug use may increase productivity in a variety of settings (Weiss & Laties 1962). Modern cultural belief and conventional wisdom demand that such evidence be explained away or ignored.

The real justification for the screening of urine in industry or elsewhere is the identification of deviant behavior. That identification may be followed by segregation, punishment, firing, surveillance, treatment or any of a variety of interventions, humane or inhumane. The conventional excuses for the humane treatment should not obscure the fact that urine screening is a probe to identify deviance, not dysfunction - a technique to investigate humans, not accidents.

Drug Testing and Analogy

The appropriate first step in a needed demystification of analytical toxicology is to point out that it, like all quantitative analysis, is indirect and constitutes analogy. The polygraph is based on the apparently incorrect analogy that variations in some physiological measurements (i.e., pulse, blood pressure, galvanic skin conductance) may be viewed as if they were a reflection of lying. Urine cannot be peered into to see the tiny components of a dissolved drug. Techniques and manipulations are used that reflect and amplify some character of the drug molecule: its binding to other chemicals, its migration with a solvent along a piece of paper or its character when ignited. Each analogue measurement and each drug may require many steps and each step may provoke error. Drug measurement is not easy. Precision drug measurement is even harder.

Drug testing is compared to other analogies to demystify it, not to demean it. The analytical methods and their developments reflect impressively skillful science and technology. Tests to identify drugs are all the more impressive because at times the analogy is so exact that it saves lives. However, the process should be described as it is and what it is: an indirect reflection of a solute in a mixed solution.

Methods With a Focus on Enzyme Multiplied Immunoassay

There are many methods in analytical drug-screening technology. All of these methods will not be reviewed here and the interested reader is referred elsewhere (Caplan 1981; Thoma, Bondo & Sunshine 1977). Furthermore, many methods are in current use for drug screening, including enzyme multiplied immunoassay (EMIT®), radioimmunoassay (RIA) and thin-layer chromatography (TLC). EMIT® is widely used in screening, but is almost certainly less often used than RIA. One important reason for this is the decision of the United States Department of Defense to rely on the RIA as its primary method of urine screening.

The principal reason for choosing EMIT® as a focus for consideration is its marketing as a test to be done on site by personnel not primarily trained as laboratory workers (Syva Corporation 1982), "because they [EMIT® tests] do not require specially licensed personnel, subjective interpretation of results or special handling techniques and safety precautions, they can be run by any trained staff member." This marketing of the product for noncentralized testing makes EMIT® the test that most needs demystifying. The Syva Corporation (1983) has even established a marketing entity called Performance Diagnostics that was "...formed to help companies evaluate the presence or extent of the drug and alcohol problem in the workplace." This service by Performance Diagnostics often includes the recommendation of EMIT® testing to the client company staff for on-site testing. The RIA, because of its use of radioactive isotopes, must generally be used in a licensed laboratory facility, although a large or moderately sized company could easily obtain a license for an on-site laboratory.

In 1972, Rubenstein and his co-workers published the first details of a "homogenous enzyme

immunoassay." Others labeled it an enzyme multiplied immunological technique, hence the acronym EMIT®, which is a trademark of the Syva Corporation.

The technique relies on modifying an enzyme's ability to act on its substrate. The presence of a drug modifies the action of a lysozyme (or other enzyme). This lysozyme ordinarily will dissolve a constituent of bacterial cell wall and cause a cloudy suspension of bacteria to dissolve and become clear. The changes in turbidity are measured by the changes in the passage or absorbance of a beam of light. Critical to the success of EMIT® is the use of immunological chemistry. An animal is injected with a drug or drug metabolite, usually in combination with other chemicals. This injection provokes the animal to produce specific immune chemicals that will bind to the drug. These antibodies to drug antigens are then harvested by extracting and purifying certain proteins (gamma globulins) from the animal's blood.

The lysozyme or other enzyme is bound to the drug or metabolite of interest (e.g., morphine, amphetamine, methadone). This drug-enzyme complex is inactivated as a functional enzyme when the drug antibody is placed in the same solution. In other words, the antibody to the specific drug will inactivate an enzyme bound to the drug. If, however, an added urine sample contains the drug in question, the antibody will bind less of the drug-enzyme complex because said antibody now binds to its destiny, the free drug. Any unbound drug-enzyme is active and lyses the bacterial suspension from micrococcus luteus, clearing the solution (see Figure 1). This clearing is measured as a change in absorbance of light using a spectrophotometer. This wordy explanation is represented symbolically in Figure 2.

FIGURE 2

Du + Ab + (D - Enz) ( Ab - Du + D - Enz *

Substrate + D - Enz * ( Product

D=drug Du=urinary drug Ab=antibody Enz=enzyme *=activation -=binding

The term "substrate," in the usual application, describes the bacterial cell wall constituent and "product" represents the material substrate now solubilized by the lytic process. The term "homogenous" is used because this mixture does not require a separation stage common to most other immunoassays. (The RIA depends on a very similar process in which an antibody, similarly produced, binds both the drug from tested urine and added radioactively labeled drug so that an assessment of bound versus unbound radioactivity reflects the drug's presence.) The term "multiplied" refers to the concept that one molecule of drug frees one molecule of enzyme, which in turn can catalyze the lysis of many molecules of cell wall substance.

EMIT® assays are now available in a variety of kits for screening urine for amphetamine, barbiturates, benzodiazepines, cocaine metabolite, methadone, phencyclidine, morphine, propoxyphene, ethanol, and urinary cannabinoids that are metabolites of marijuana. The EMIT® method employs several different enzyme systems available in different assay products. Lysozyme (derived from egg white) is used in the EMIT-dau® system, which can reflect opiates, barbiturates, amphetamine, benzodiazepines, cocaine metabolite, methadone and propoxyphene. Malate dehydrogenase is used both in the EMIT-dau® and the EMIT-st® cannabinoid assays. Glucose-6-phosphate dehydrogenase (G6PDH) is used in EMIT-dau® tests for methadone and phencyclidine as well as other EMIT-st® versions of compounds listed in the

above EMIT-dau® examples. The EMIT-st® version for ethanol requires alcohol dehyrogenase. These alternate enzymes are all activated as described above, but have different substrates that lead to absorbance changes measured spectrophotometriclly. The EMIT-st® tests are designed to reflect only the presence or absence of the drug and are qualitative. The EMIT-dau® systems incorporate a series of standard solutions ("calibrators") that in comparison to the sample can yield a semi-quantitative analysis.

In summary, the EMIT® tests utilize complex immunochemistry and the production of drug antibodies in interaction with enzymic detectors to reflect the presence of various drugs subject to misuse. Of course, the method can be used to assess other chemicals, both therapeutic and toxic. With this background, some specific issues can be discussed, particularly in light of current marketing thrusts toward primary on-site drug screening.

Sensitivity and False Negatives

The EMIT® method is very sensitive and false negatives rarely occur. Table I lists levels of detection in the urine for some of the most important drugs of interest. Of course, it is possible that a drug assay reported as negative may contain very small amounts of a drug or be very diluted by large urine volumes, but this test meets an important requirement of a screening test in that it reliably reflects small amounts of the drug. However, some factors may alter this sensitivity. EMIT® performs optimally when urine pH ranges between 5.5 to 8.0. Samples that are old may have undergone significant pH change and are likely to present false negatives because such changes may alter enzyme function, among other factors. The addition of NaCl in concentrations of 20 mg/ml probably inactivates enzyme activity because of ionic effects and, thus, all EMIT® tests become negative (Kim & Cerceo 1976). Other ionizing salts placed in urine may also yield this effect and a measure of specific conductivity shows a negative correlation with EMIT® function (Anderson & Erikson 1977). Whether this factor is being exploited by drug users is unknown, but at some point very close observation of voiding could become a mass event as well.

Specificity and False Positives

Conceptually, a false-positive result is easily understood. Can a sensitive test be positive when the drug sought is not there? The answer is clearly yes. In a research situation or a nonpunitive screening, even a high false-positive rate is of minimal importance. However, in a screening program directed at probationers, individuals undergoing preemployment or prepromotion examinations or job fitness evaluations, the reporting of a drug-positive urine takes on great social significance. The occurrence of a false positive is much more important then a false negative. As with most politically important terms, the definition of "false positive" is subject to tedious argument. Proponents of and apologists for screening prefer the term "unconfirmed positive." The rhetorical implication of such a stance is clear. If one has merely not confirmed the positive then it still may have been a positive. This is not far from sophistry. In fact, the choice of the phrase signals the necessity to confirm all positives, simply because the EMIT® test (and other immunoassays) are less specific than one would wish. The issue of confirmation will be discussed further. Generally, a false positive is by definition equivalent to an unconfirmed positive when a reasonable attempt has been made to confirm by using an analytical test that exploits a different screening method and is at least as sensitive as EMIT®. The failure to confirm EMIT® may occur for several reasons. First, positive reactions may occur due to a carry-over following a preceding sample that was strongly positive (Syva Corporation 1982). To this might be added other operator errors, such as contamination of other equipment or failure to cleanse glassware. Operator error, present to some degree in all technologies, requires emphasis in a proposed on-site system using nonspecialist personnel. Second, positive reactions may occur due to the reactive presence of other chemicals that bind to a particular antibody and, third, positive reactions may, occur due to endogenous human urinary enzymes that mimic the effects of the detector enzymes.

In addition, false-positive reactions may occur for reasons still unknown. Perhaps the technology that binds a large enzyme to a small drug molecule is not error free.

Cross-Reactivity

According to Bost, Sutheimer and Sunshine (1976), "The greatest defect of immunoassays is their lack of specificity. Very few anti-sera exist that are specific for a single compound, although some have been prepared with very high specificity where cost was no object. Hence one should confirm all positive results by some other procedure if specificity is important. Clearly, it is essential to know what specific substance is present in certain forensic medicine problems because (e.g.) a job may be in jeopardy or a potential parole violator incarcerated."

Antibodies to drug antigens are variously nonspecific and may bind to other chemicals. For example, the EMIT® antibody, which is produced by the injection of a nitrogen substituted amphetamine-protein conjugate, cross acts with a large number of phenylisopropylamines, some of which have importance in clinical medicine. In fact, methamphetamine and ethylamphetamine react more strongly with the amphetamine antibody than does amphetamine (Budd 1981a).

The commonly used over-the-counter (OTC) phenylisopropylamines, ephedrine and phenylpropanolamine (PPA), react with the antibody in clinically obtained concentrations (Budd 1981a). Some cross-reactivity may be advantageous to the goals of screening. The appearance of either amphetamine or methamphetamine will cause reactivity and both are misused drugs. However, the appearance of counterfeit amphetamine has become common (Morgan & Kagan 1978). Previously popular amphetamine formats are manufactured using a variety of less potent stimulant drugs, such as PPA, ephedrine and caffeine. Many amphetamine positives via EMIT® are likely to be nonamphetamine products resultant from the counterfeits or from legitimate cold-cough or antiasthmatic products.

Aware of this problem, Syva Corporation sells an amphetamine confirmation kit that depends on differentiation (after chemical reaction) of products with the ß-hvdroxyl group, such as PPA and ephedrine, from those without, such as amphetamine and methamphetamine (see Figure 3).

One is likely to provoke an argument with EMIT® enthusiasts if one calls a positive amphetamine screen that was caused by PPA in Sinu-Tab® a false positive. However, this author wishes to do so. If one encounters a positive test for amphetamine and then in turn spends money on an amphetamine confirmation test that is negative and confirmatory gas-liquid chromatography that reveals that the product is PPA or ephedrine, one might as well face up to the difficulty and call it a false positive.

The cross-reactivity by which the opiate test is positive for heroin is lauded. However, this test will also be positive for legitimate codeine and hydromorphone or a popular ingredient of cough syrups in Europe, pholcodine (Svenneby, Wedege & Karlsen 1983).

The issue of cross-reactivity was studied by Allen and Stiles (1981), in which 161 drugs were tested on EMIT-dau® screens for opiates, amphetamines, barbiturates, benzodiazepines, methadone, propoxyphene and cocaine metabolite. Of these 161 prescription and OTC products, 65 caused some false positives to occur, with some of these drugs provoking false positives in as many as four of the seven EMIT® tests. Most of these positives occurred at concentrations of the tested drug that are not achievable in human urine and are not practical problems. However, they do illustrate the issue of cross-reactivity (or enzyme disruption) and should indicate that future chemical variants may be reactive. Only the cocaine screening test, which depends on detection of the cocaine metabolite benzoylecgonine, was completely free of cross-reactivity. However, the methadone screen was nonspecific enough so that many compounds showed cross-reactivity. In Table 11, medicinal products are listed from the study by Allen and Stiles that

caused reactions at concentrations in urine of 100 ug/ml or less. Part of the remaining uncertainty about cross-reactivity exists because studies of cross-reactivity are almost always done by adding pure compounds, directly to human urine. Most of the drugs listed in Table II do not reach concentrations of 100 ug/ml in usual human use. However, the tests should be done on humans consuming the drug, because such studies would examine the neglected possibility that metabolites of chemicals contribute importantly to cross-reactivity. Many of the EMIT® antibodies (e.g., opiates, benzodiazepines and propoxyphene) react to human metabolites of the primary compounds.

In Table III, all cross-reactants found in the literature resultant from both the addition of drugs to human urine and studies of humans taking the compounds are compiled. These are compared to the cross-reactants listed in the Syva Corporation literature supplied to the author on request from the company.

Reactions Due to Human Enzymes

Of the enzymes utilized by EMIT®, both lysozyme and malate dehydrogenase appear in human urine (Arcenal & Osterloh 1982; O'Connor & Regent 1981). Alcohol dehydrogenase and G6PDH ordinarily do not.

A false-positive test could occur in some individuals because they excrete unusually large amounts of endogenous lysozyme or malate dehydrogenase. Because of this problem, a blank should be run with all positive tests employing either of these two enzymes. This is stated in the Syva Corporation brochures for the pertinent EMIT-dau® tests, but is omitted in the EMIT-st® cannabis booklet. It is also not shown in a booklet that depicts in a pictorial fashion the ease of doing the cannabis tests (Syva Corporation 1982). These points are not made to accuse Syva Corporation of ignoring the problem, but of a certain indifference in the face of selling the kits to be used by personnel not primarily trained in laboratory techniques. This author has informally and nonsystematically asked on-site users of the cannabinoid EMIT-st® method if they were cautioned to run blanks, and received only negative answers.

The lysozyme problem may be greater than initially stated. A recent article by Arcenal and Osterloh (1982) noted the appearance of lysozyme at levels high enough to interfere in 10 percent of samples run at one laboratory. The article also described a failure to find an easy resolution of the problem. This was a hospital-based clinic population and high urinary lysozyme may have reflected a higher than usual incidence of renal disease.

False Positives (or Unconfirmed Positives) in the Real World

A careful, skilled laboratory, one may assume, will have minimal operator error, will run blanks on all positives and will anticipate common cross-reactants. Despite this, a number of studies (none done on-site) reported false positives (see below). In this literature, reports of a percentage of false positives referred to the percentage of positive EMIT® tests that were not confirmed by alternate tests. A 10 percent false-positive rate does not mean that of all people tested, 10 percent yielded false tests. Rather, a 10 percent false-positive test rate means that of those found positive, 10 percent could not be confirmed. These cited studies were seldom critical of EMIT®. In fact, most contained favorable opinions.

A survey of urines from drug abuse treatment programs reported that 10 percent of EMIT® positive tests were unconfirmed by TLC and in a focused study of barbiturates, a 9.7 percent false-positive rate emerged (Oellerich, Kulpmann & Haechel 1977). In a study by Fletcher (1981), 26 subjects required to submit urines because of forensic cases (usually auto accidents) underwent EMIT® urine tests. There emerged a total of 22 unconfirmed positives (five for amphetamine, seven for benzodiazepines, six for opiates and four for propoxyphene). This study truly reported some unconfirmed positives because, at times, EMIT® was the sole test. Fenton and colleagues (1980) identified a 6.6 percent false-positive rate for

benzodiazepines. In an early study by Mule, Bastos and Jukofsky (1974), urines from a series of New York State drug abuse treatment programs provoked false positives: 8.7 percent false positives for morphine; 2.6 percent false positives for methadone; 5.6 percent false positives for opiates; 12.5 percent false positives for amphetamine; 5.1 percent false positives for barbiturates; and 10.0 percent false positives for cocaine. The authors of the article logically enough state that "...additional analysis must be performed to confirm the presence of drug in biological material after a positive result...."

The issue of independent confirmation already mentioned is critical. A positive test by EMIT® or other method used for primary screening should be confirmed by an alternative analytic method. In fact, RIA or EMIT® should not back each other. For example, the morphine antibody used in the Roche Abuscreen® RIA is close in structure to the EMIT® antibody (Willette 1984). There are a variety of arguments around this issue growing out of the experience of the U.S. military (to be discussed below). Many commentators now feel that a positive immunoassay screen must be confirmed by gas chromatography plus mass spectrometry (GC/MS). This may be particularly applicable when an accused individual brings suit after losing job or status privileges.

Military Screening Programs

One should not be surprised that a military command structure would decide that mass screening of enlisted personnel for drugs would be a desirable tool. Although much of this article has discussed the EMIT® test, it has a relatively minor role in the following story. The problems of laboratory performance, faulty confirmation, legal action and carelessness do.

In February 1984, Lieutenant Colonel Michael Clarke announced that the Army and the Air Force were reviewing the results of 100,000 urinary drug tests administered between April 1982 and November 1983. An American Civil Liberties spokesperson estimated that as many as 30,000 military personnel might be eligible to have disciplinary action against them dismissed.

The Navy had experienced similar problems. In 1982, the Navy began a massive urinary surveillance program. Naval laboratories increased their activities from 800 tests per month to 10,000 tests per month in each of four laboratories. By July 1982, a number of naval commanders began questioning the frequent occurrence of positive specimens. Six thousand (6,000) positive urines reported between January and September 1982 were reexamined. Of these 6,000 samples, some 2,000 could not, according to the Navy publication All Hands (Unsigned 1983), "be scientifically substantiated as positive." Another 2,000 samples were missing some form of documentation. This author has not learned whether these failures were in terms of chain of custody, handling of data, operator error, failure to confirm false positives or some combination thereof. Lieutenant Commander Deborah Burnette, a Navy spokesperson, stated that sometimes the same test was used for both the finding and confirmation. In another interview with Burnette, it appeared that she was referring to the fact that at least one of the Navy labs used EMIT® as a back-up test to RIA. The Navy subsequently announced that it will not use EMIT® in this fashion again. The Navy is the only important current military user of EMIT®, where it is chiefly employed on site on ships at sea.

The Army had stopped using Navy labs in 1982 because a number of Army personnel (probably 1,200) had been affected by these Navy laboratory problems. However, the Navy's 1982 problems had apparently been paralleled by errors at the Army's Fort Meade tab. Problems at this lab emerged when a civilian lawyer aggressively defended soldiers disciplined on the basis of reports indicating marijuana use. (All Army and Air Force primary screens for marijuana use utilize RIA.) Because these men refused offered administrative punishment, they were subject to court-martial. They were then entitled to a defense that demanded that the lab records be examined by civilian experts. Many court-martials depending on these records were then dropped.

These events led to the appointment of an investigative commission under the leadership of Major General David Einsel, a deputy assistant to the Secretary of Defense. This commission utilized civilian consultant toxicologists. The commission was later criticized by a nonconsultant civilian toxicologist, Arthur McBay, who once had been a Navy consultant. McBay objected to the fact that civilian consultant Dr. Robert Willette was at the time a consultant to the Navy Military Personnel Command and Dr. Mahmond A. Elsohly worked in the late 1970's for Dr. Carlton Turner. McBay feared this biased their views in favor of drug testing methods currently in use by the military.

The Einsel Commission Report was partially presented in December 1983 at a White House meeting, but was not fully reported until March 1984. It reported a devastating error rate and stated that the following percentages of positive tests at four major facilities (i.e., Fort Meade, 97 percent; Brooks, 60 percent; Wiesbaden, 75 percent; Tripler, 20 percent) from April 1982 to November 1983 demonstrated "a basis for argumentation as to legal or technical credibility or sufficiency." The Commission Report stated that many problems were now solved.

For reference, the Army and Air Force were performing approximately 800,000 tests per year at these facilities and in the 20 months approximately 1,320,000 tests had been performed. The rate of positive reports was approximately 10 to 12 percent. This probably explains the 100,000 figure given as the number needing review in an earlier estimate.

The Einsel Commission Report also indicated that most errors were not related to the tests themselves but to poor management, inadequate personnel, broken chain of custody, and faulty maintenance and transmission of reports and records. Einsel maintained that his commission found "no false positives." This statement seems untenable. A former commander of the Brooks lab estimated a false-positive rate of three to five percent based primarily on contamination of glassware with positive urine. Two civilian toxicologists were given 60 positive reports from Fort Meade for review and they identified five positive screening tests that were subsequently found to be negative on a confirming test. A final criticism of the Einsel Commission Report occurred because of its recommendation that screening tests be confirmed by GC. Some critics felt that the confirmation should include GC/MS because a number of GC-alone confirmations were reported to be inaccurate. These annual screening tests now include probably 13 million RIA screens in nine laboratories: Navy (5), Army (3) and Air Force (1). The Navy continues to use at least 30,000 EMIT® tests per month.

Laboratory Quality Control

Mass urinary screening is a difficult business. The immunoassay tests that are extremely valuable and impressive tools in some settings may not have performed so well in mass screening settings. Some of the difficulties reside in the imperfect nature of the technology and some reside in the imperfect nature of the operator. Indeed, one can imagine the astonishingly boring work of handling thousands of specimens with only an occasional positive result to excite, which may be potentially false.

This article has not concentrated on EMIT® because it is a particularly bad test, but because its sellers apparently wish to place it on site at many American industries. What reason does one have to believe that these relatively undertrained personnel will do well even if the fears raised about cross-reactivity and urinary lysozyme are overemphasized? The answer is very little if the few reports are true that assessed the competence of clinical labs that are not on site.

According to Lundberg (1972), "The performance of even the 'best' toxicology laboratories on urine drug screens is grossly detective, with frequent false positives and false-negative results and misidentifications." Lundberg cited other studies (Sine & Murray 1972; Fujimoto & Wang 1970) and an unpublished survey by the California Association of Toxicologists. in this latter survey, he cited a 20 to 70 percent error on

unknown samples, describing unpublished data gathered by state corrections' officials.

In a later paper, Dinovo and Gottschalk (1976) surveyed the competence of nine laboratories to assess unknown samples in both urine and a solution of human albumin. They found that "the results for the proficiency samples point out startling interlaboratory differences in accuracy and precision of detection of drugs." Their report chiefly described false negatives. Only two of nine laboratories associated with coroners' offices identified and quantified all of the six unknown drugs. There were 18 failures to find drugs in 54 opportunities. Another group of laboratories consisting of forensic, commercial and clinical facilities did not fare any better, with 31 failures out of 95 possible findings. Six of the 19 labs identified drugs that were not there.

EMIT® Cannaboid Tests in the Field

A critical problem in assessing EMIT® as to overall performance and suitability is the absence of interpretable field tests. The Syva Corporation product literature essentially always refers to in vitro laboratory testing to confirm that the test is both reliable and accurate. The procedure is very clearly described by Syva Corporation scientists (DeLaurentis et al. 1982) in a NIDA research monograph. After carefully explaining the EMIT® method, a technique of confirmation is described and depicted. Normal urine not containing marijuana metabolites was tested by EMIT® and compared with the same urine to which 50 ng/ml of 11-nor-delta-9-tetrahydrocannabinol-carboxylic acid (delta-9-THC-acid) had been added. The display showed precise separation between normal and the same normal, but spiked, urine. This same display depicted in the NIDA research monograph (see Figure 4) is used in the Syva Corporation product literature. It is distressing that the amount of delta-9-THC-acid was never quantified, but was always presented as the percentage of urine versus "separation units" or "assay response rate." This author cannot easily interpret such units and wonders if the overlap between normal and spiked urine would be more prominent if it was displayed in quantitative terms.

In the introduction to this paper, a polygraph study done under field conditions was referred to. It is not unreasonable to ask for the evaluation of EMIT® under field conditions, but there are relatively few such studies. Three evaluations of EMIT® in the field were located. Although all three have problems, they should be placed against the in vitro evaluations of spiked urine samples. Indeed, field evaluations are always problematical. Specimens may not be ideally collected or handled. Subjects may present urine containing an interfering drug or drug metabolite, or they may have renal tubular disease increasing the amount of lysozyme or malate dehydrogenase in the urine. Field technicians may not be aware of these problems and the rate of operator error may be high. None of these field studies evaluated the most important variable, the briefly trained workers who are to be the on-site operators. Despite these warnings, all who are interested in these issues should want to know how EMIT® performs under field conditions. All three evaluations described below are evaluations of the EMIT® cannabinoid test and some important methodological and pharmacological issues will again be briefly reviewed.

The EMIT® cannabinoid systems use an antibody prepared to the tetrahydrocannabinoid metabolite delta-9-THC-acid. The metabolite is covalently linked to a pig heart malate dehydrogenase, which is inactivated by the binding of the antibody. The detection system utilizes a spectrophotometer, which detects conversion of the coenzyme nicotinamide adenine dinucleotide to its reduced form, nicotinamide adenine dinucleotide hydrogenase. All three field trials used GC/MS as a confirmational test, sometimes with other tests as well.

Center for Human Toxicology Trial

In 1982, the NIDA research monograph on analysis of cannabinoids in biological fluids contained a field evaluation of the EMIT® cannabinoid test conducted by the Center for Human Toxicology (CHT) at the

University of Utah (Peat, Finkle & Deyman 1982). Briefly, the CHT coordinated the confirmation of EMIT® positive urines for delta-9-THC-acid mailed to them from 12 cooperating analytical labs. Most specimens had been obtained from auto accident casualties, but others originated from emergency room admissions. These positive specimens were sent to a single test sight for confirmation. In addition to the samples from cooperating laboratories, the CHT itself assessed a number of specimens and compiled a separate listing for those. The performance of EMIT® was disappointing. For the 12 laboratories, the rate of unconfirmed positives was 11 percent. The CHT nonconfirmation rate was much higher. Of 98 EMIT® positive samples, 37 were unconfirmed by GC/MS: a 38 percent false-positive rate. However, an important technical problem clouded the issue. During the evaluation, it became known that most delta-9-THC-acid in the urine is conjugated to glucuronide (Williams & Moffat 1980). The GC/MS method had been developed for free delta-9-THC-acid. This information became available too late to recheck all specimens after a hydrolysis step to convert bound material to free. Some unknown percentage of samples had in fact been hydrolyzed. A few specimens were analyzed both before and after hydrolysis. In almost every instance, the hydrolysis did increase the amount of delta-9-THC-acid measured by GC/MS, but some still remained negative and unconfirmed after hydrolysis. The authors and later commentators believed that this technical problem explained "the poor correlation between the EMIT values and those obtained by GC/MS." There has never been a published attempt of which this author is aware to replicate the study and it has never been confirmed that the hydrolysis is of critical importance.

The O'Connor-Regent Study

In 1981, O'Connor and Regent published a study in which cannabinoid EMIT® positive urines (submitted voluntarily and anonymously by college students) were subjected to attempted confirmation by GC/MS. Of 144 positive urines, the authors sent 60 for confirmation to collaborating laboratories. Overall, only 50 of the 60 were confirmed: a 17 percent false-positive rate. Twenty-four (24) of 30 specimens were confirmed by GC/MS. Seventeen (17) of 20 other specimens were confirmed by GC/MS after hydrolysis. This Indicates that even with hydrolysis before GC/MS, the false-positive rate was 15 percent. It seems clear that hydrolysis does not solve the problems. It also seems clear from reading the study that careful laboratory efforts, including the running of blanks to rule out endogenous urinary malate dehydrogenase, were observed.

New Jersey Department of Corrections

In recent years, a number of court cases have been heard in which inmates of a state correctional system have brought suit to protest the use (apparently widespread) of a single unconfirmed EMIT® test to bring about disciplinary action against inmates. In New Jersey, as in a previous Massachusetts case, the court decided that such action was inappropriate and the state was ordered to cease such activity.1

In preparation for this case, the Department of Corrections sent 400 EMIT® positive cannabinoid tests on inmates to the Roche Clinical Laboratories in Raritan, New Jersey. Of these, 107 were unconfirmed by RIA, an inappropriate confirming test. These same 107 tests were sent to Roche Analytic Laboratories in Richmond, Virginia, where all were unconfirmed by GC/MS (after hydrolysis). This constitutes a 1984 field trial of EMIT® cannabinoid tests in which the false-positive rate exceeded 25 percent. The EMIT® tests were run by a trained laboratory technician employed in a state laboratory. These data were not presented in the court hearing. The state agreed to submit to the order and agreed to use confirmation tests on all EMIT® positives without argument.2

Conclusions

XIV. a. Table I. Drug Detection Limits (SYVA Corporation 1982 XIV. b. Table II. Cross-Reactivity With EMIT® Test at 100 (G/ML or Less) (ALLEN & STILES 1981)

XIV. c. Table III. Cross-Reactants

Technology traps people and they begin to serve the technology more committedly than it serves them. Such entrapment is aided by a refusal to be critical in the face of flawed technological approaches. Demystifying the testing and focusing on the real world performance slows such entrapment.

The Syva Corporation wishes to supply on-site EMIT® for relatively untrained personnel to engage in difficult biochemical manipulations. There are no data confirming that such personnel can do this work adequately and the EMIT® test has consistently failed field condition analysis. This author is convinced that such use of EMIT® is improper.

XIV. a. Table I. Drug Detection Limits (SYVA Corperation 1982)

Drug Detection Limit

morphine 0.5 ug/ml>

methadone 0.5 ug/ml>

amphetamine 2.0 ug/ml>

secobarbital 2.0 ug/ml>

benzoylecgonine 1.6 ug/ml>

oxazepam 0.7 ug/ml>

propoxyphene 2.0 ug/ml>

XIV. b. Table II. Cross-Reactivity With EMIT® Test at 100 (G/ML or Less) (ALLEN & STILES 1981)

Generic and Brand Names

EMIT® Test

Am Ba Be Co Me Op Pr amitriptyline Hcl (Elavil®) X carisoprodol (Soma®) X clindinium bromide (Quarzan®)

X

cloxacillin Na (Tegopen®) X diphenhydramine Hcl (Benadryl®)

X

ethoheptazine citrate (Zactane®)*

X

imipramine Hcl (Tofranil®) X isoxuprine Hcl (Vasodilan®)

X

orphenadrine citrate (Norflex®)

X

perphenazine (Trilafon®) X promethazine HCl (Phenergan®)

X X

thiethylperazine maleate (Torecan®)

X

tripelennamine Hcl (Pyribenzamine®)

X X

*No longer marketed in the United States Am=amphetamine Ba=barbiturate Be=benzodiazepine Co=cocaine Me=methadone Op=opiate Pr=propoxphene

XIV. c. Table III. Cross-Reactants

From Syva Corporation Product Literature

From Medical Literature (Hausmann et al. 1983; Svenneby, Wedege & Karlsen 1983; Allen & Stilles 1981; Budd 1981a, 1981b)

Amphetamine

methamphetamine clortermine

phentermine benzphetamone

mephentermine phenmetrazine

ephedrine indomethacin

nylidrin tranylcypromine

phenylpropanolamine tuaminoheptane

isoxuprine

Benzodiazepine (Oxazepam) chlordiazepoxide clindinium

diazepam cloxacillin

flurazepam tripelennamine

lorazepam temazepam

N-desalkylflurazepam halazepam

N-desmethyldiazepam nitrazepam

flunitrazepam

clonazepam

chlorazepate

Opiate

morphine pholocodine

codeine dosylamine

hydromorphone ethoheptazine

nalorphine promethazine

meperidine

oxycodone

(Top)

Notes

1. Denike v. Fauver (U.S. District Court for New Jersey, May 14, 1984; D..J. Debvoise, U.S. District Judge).

2. This author is grateful to the New Jersey Department of Corrections for permission to publish this data. They state that the current nonconfirmation rate is much lower.

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Copyrighted material. Reprinted by permission.