Medical Expert Witness Forensic Toxicologist | Medical Expert Witness Services & More | Dr. Nachman Brautbar

Intoxication, Drugs of Abuse Testing
& Forensics Application

By Nachman Brautbar, M.D.

Recreational use of and abuse of illicit and prescription drugs has grown in the last 15 years, and become a point of concern to both forensic and non-forensic physicians. Various regulatory agencies, insurance companies, and medicolegal processes such as workers compensation and personal injury defense have been utilizing the defense of intoxication (drugs of abuse and alcohol or a combination of either) in order to prove or disprove liability for injury.

Biological Samples for use in Drug Testing
Commonly, three types of biological samples have been utilized: 1. Blood. 2. Urine. 3. Hair. This determines if a patient has used drugs (to strictly determine if the use occurred, as opposed to being under the influence), hair will retain drugs for several months, most commonly 3 months after the use. Urine will retain drugs or their metabolites for anywhere from several hours to several days, or in some rare occasion weeks, and blood will retain the drugs or their metabolites for several hours. Therefore, the use of blood is not relevant to determining whether the patient has used drugs in the past (several days to weeks).

To determine whether the person is impaired as a result of a drug abuse, blood is the best biological tissue to be tested and the most accurate, because the levels in the blood or the presence of the drug in the bloodstream is a very important objective determinant in the process of diagnosing or ruling out the "impairment or under the influence of drugs or the intoxication defense.

Does Positive Blood Testing, Urine Testing or Hair Testing Indicates Impairment?
Positive hair samples for drugs of abuse does not equate with impairment, it only can determine that in the past a patient has been using drugs (with a given limit). The presence of drugs of abuse in the urine can absolutely not be equated with impairment, but rather use in the last day or several days, and in some extreme cases a week. The presence of drugs or their metabolites in the blood testing does not prove impairment, because there is no scientific data to extrapolate the exact level of illegal drugs that will impair a specific user. That type of extrapolation has been made only for alcohol, which has a legal definition in driving statures, Federal and State, as well as medical forensic extrapolation formulas. (For instance, the blood alcohol disappearance curve.) Commonly a forensic toxicologist and forensic physician will be asked to determine whether urine positivity for illegal drugs indicates that that person was Aunder the influence@ or Aintoxicated@ when an accident occurred on the job, or a car accident occurred on the road. The presence of drugs of abuse or even prescription medication in the urine, or their metabolites in the urine, can not be equated with impairment. Unless clinical data from the site of injury or prior to the injury can indicate that the patient was behaving as an impaired person, even then it will be very difficult to establish impairment. The presence of drugs or their metabolites in the blood may support impairment based on the blood levels and the clinical behavior.

Drug Recognition Expert Program
Due to the problem with identifying impaired workers and driver's in relation to drug blood concentration, the Los Angeles Police Department has developed a program which is called the Drug Recognition Expert Program (DRE). This program started initially with training officers to recognize behavior and psychological status associated with psychoactive drugs, and over the time has attracted the attention of other agencies who were experiencing similar problems. Based on the evaluation the DRE forms an opinion as to: 1. Whether the suspect is impaired. 2. If impaired, whether the impairment is related to drugs. 3. If related to drugs, which drug category or combination of categories is causing the impairment. A recent study (Governor's office of Highway Safety) the police department and DRE program, utilized data software developed by Southern California Research Institute under National Institute on Drug Abuse funding, to record and analyze this data. A patient bank for 390 men and 108 women drivers was analyzed. The DREs correctly identified at least one drug category in 91% of 415 specimens which the laboratory confirmed one or more drugs. No drugs were found in specimens from 26 individuals who the DREs judged not impaired by drugs. The DRE decisions were supported for 83.5% of 484 specimens, and not supported for 16.5 specimens (indicating a significant rate of error).

What is interesting in these studies, is that in 14 cases, the DRE entirely missed the drugs found in urine, and in 47 of the specimens for which the laboratory confirmed multiple substances, the DRE decisions were combinations of hits, false positives and false negatives. The DRE missed marijuana more often than other drug categories, but it cannot be determined whether the misses were DRE error or a consequence of the drugs' time course. Since the drugs principal metabolite can be detected in urine for days to weeks, a specimen may test positive even though it was obtained at a time when active marijuana was not present. A marijuana positive in urine which is not supported with evidence of behavioral impairment, cannot and does not speak to the question of drug Aintoxication@. This scientific fact is commonly, and for some reason, forgotten or is unknown to some forensic physicians who have the professional and ethical responsibility to evaluate whether the patient was under the influence of illicit drugs. For instance, on one occasion, I remember a patient who was involved in a truck collision while on the job, and his urine tested positive for marijuana. The forensic examiner opined that the patient was Aunder the influence@, despite the fact that the emergency room notes and the paramedic notes clearly stated the patient was alert x 4. As a matter of fact, in the study of DRE quoted above cocaine misses occurred with the second highest frequency. Behavioral science show that stimulants are often difficult to detect, but it cannot be determined with certainty whether the misses are true errors. Since the half-life of cocaine effects is approximately 90 minutes, and the metabolite (breakdown products of cocaine) benzoylecgonine (BE) is known to have no psychoactive effect and can be detected for 24 or 48 hours (usually), urine positive for BE does not mean that the suspect was Aunder the influence@ during the evaluation.

The Clear Message from these Studies is

  1. The presence of drugs of abuse in the urine cannot be used for the Aintoxication defense.
  2. The presence of drugs of abuse in the blood cannot automatically be extrapolated to the Aintoxication defense. Each case requires careful analysis of the medical records and the clinical reliability of the blood levels.
  3. The presence of drugs of abuse in hair has no meaning whatsoever and cannot support the Aintoxication defense. The only extrapolation to be made is that drugs were used sometime in the past.

Medications and Substances Causing False Positives
There are 161 prescription and over-the-counter medications which have been studied and show that 65 of them produce false positive results in the commonly administered urine test for drugs. Siegel, according to the Los Angeles Times report, (a psychopharmacologist at UCLA), said "The widespread testing and reliance of tale-tale traces of drugs in the urine is simply a panic reaction invoked, because the normal techniques for controlling drug use have not worked very well. The next epidemic will be testing abuse." The most commonly used urine testing methodology is AMIV, has been shown that over 250 over-the-counter medications and prescription drug interactions can cause false positive testing using this methodology. The following have been reported as causing false positive tests are shown in the next table.

TABLE 1: Medications/Substances Causing False Positives/Cross-Reactions (Preliminary Testing)


Pain relievers such as Advil, Nuprin, Motrin and menstrual cramp medications like Midol and Trendar. All drugs containing Ibuprofen. Passive marijuana smoking. It has been described that passive marijuana inhalation at a rock concert can test positive in the urine despite the fact that the person has not been using marijuana.


Dristan Nasal Spray, Neosynephren, Vicks Nasal Spray, Sudafed, and others containing ephedrine or pnenypropanolamine.


Vicks Formula 44M containing Dextromethorphan, and Primatene-M containing perylamine, as well as the pain reliever Demerol and prescription anti-depressant Elavil, and even Quinine Water


NyQuil Nighttime Cold Medicine


Antibiotics such as Ampicillin and Amoxicillin.


Diazepam, as well as some ingredients in cough medicines, Dextromethorphan.

Poppy seeds such as on a Burger King roll, bagel rolls (according to the Journal of Chemical Chemistry, Volume 33, #6, 1987), quantities of poppy seeds ingested in this study 25 and 40 grams, may be expected to be contained in 1 or 2 servings of poppy seed cake. Therefore, poppy seeds represent a potentially serious source of falsely positive results in testing opiate abuse. The paper in Clinical Chemistry also concludes: "Not only is it difficult to distinguish heroine or morphine abuse from codeine, but dietary poppy seeds can give a strong positive results for urinary opiates for several days duration that is confirmed by GC/MS analysis."

The list of agents which can cause false positivity in the urine has also been described for endogenous excretion of enzymes in the urine. For instance, a study from Emory University by Dr. James Woodford, has shown that a percentage of persons of African origin, orientals and Pacific Islanders may be testing positive for marijuana secondary to a mechanism which involves the pigment melanin which protects the skin from sun, which approximates the molecular structure of the THC metabolite which causes laboratory cross reaction with marijuana.

What this means is that if you have used any of these over-the-counter medications, you may be accused (arrested) based on a false positive urine test. If your expert does not pick this up you may be in serious irreversible trouble.

Methodology of Drug Screening in Urine
There are several methods to detect drugs in the urine. The most frequent one is an enzyme immunoassay (EIA), or radioimmunoassay (RIA), and florescence polarization immunoassay (FPIA). There are additional more sophisticated methodologies which are performed on extract of urine which are performed using thin layer chromatography (TLC), gas chromatography (GC) high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GS/MS). The only accepted procedures based on the definition of the National Institute of Drug Abuse (NIDA), and the Department of Defense (DOD), are immunoassays followed by gas chromatography/mass spectrometry confirmation. The confirmation utilizing gas chromatography/mass spectrometry is required since the methodology of immunoassay can give false positive results due to cross reactivity. This is due to the fact that this methodology cannot specifically identify the drug, but rather the antibodies recognize substances which may have the same structure chemically, or immunologically or enzymologically, other than the drug of interest. Immunoassays for amphetamines will show reactivity with drugs structurally related to amphetamines, such over-the-counter sympatomedicoamines, phenylpropanolamine and ephedrine, over-the-counter legal medications used for nasal congestion, cold and appetite suppressant. Confirmation therefore is a must utilizing gas chromatography/mass spectrometry. The use of gas chromatography/mass spectrometry provides an extremely high index of reliability when properly preformed and applied.

As far as gas chromatography/mass spectrometry, this is a superb methodology if done correctly. For instance, if the equipment has not been cleaned appropriately, the previous run from the previous testing will contaminate the next sample, and will give erroneous, inaccurate and incorrect results. Therefore, it is mandatory to look into the methodology that the person used for specific results on gas chromatography/mass spectrometry at a given indicated case. (On many occasions a deposition of the lab technician will reveal that the sample was contaminated.)

What this means to you is that if your urine is tested utilizing the immunological method only, without confirmation with GS/MS, there is a high probability that the result may be a false positive and irrelevant to your situation.

Forensic Accuracy of GS/MS
Gas chromatography/mass spectrometry is extremely and highly accurate if done correctly. A laboratory which performs the test must be NIDA certified or CAP (College of American Pathologists) certified. All of the labs that perform the gas chromatography/mass spectrometry on site can be NIDA certified. Labs that send samples to another laboratory for gas chromatography/mass spectrometry confirmation are ineligible, I repeat, ineligible, for NIDA certification. Therefore one must be very careful when looking at the test results to see whether the laboratory is NIDA/CAP certified. Furthermore, some labs do not properly and thoroughly clean the GC/MS equipment. Some labs don't even do GC/MS confirmation. Some labs use cheap alternative methods to increase profits and reduce expenses. Therefore you must be in a position to aggressively cross examine the laboratory director and technician.

Drug of Abuse and Hair Testing
Hair testing for drug of abuse testing has become extremely popular among employers. There have been several scientific forensic doubts about the use of this methodology for proof of abuse. For example, the Society of Forensic Toxicologists in 1990 stated: "The use of hair analysis for employees in pre-employment drug testing is premature, and cannot be supported by the current information on hair analysis for drugs of abuse." A 1997 study by the National Institute of Drug abuse reached a conclusion and indicated that significant ethnic bias may be the result of test for cocaine positivity. Analytical Toxicology in its issue in March/April 1998 indicated that removal of melanin from hair (a methodology used to remove the ethnic bias) "does not eliminate the hair color bias when interpreting cocaine concentrations" Public information available (Congressional records from May 14, 1999), indicated that the Department of the Army secretary raised questions about the Army's use of hair testing in a specific case, and members of Congress were expressing their discomfort with the procedure's reliability. Indeed, Representative, Cynthia McKinney, a Democrat of Georgia, and from Defense Secretary, William Cohen, that she is exploring possible Legislative remedy to prohibit human hair testing for drugs in the military, given that the hair testing has been proven by forensic toxicologists to be racially biased. Indeed, the paper by Kintz, et. al. published in the Journal of Forensic Scientific International, January 1997, Volume 17, pages 84 to 123 and 151 to 156, indicated that false positives are found even at low concentrations. Tissue hair analysis in good hands with good laboratory technology may give an idea about habitual use of some of the drugs; however, it is preferable that these should be combined with urinalysis utilizing either screening, or better confirmation methodology.

Practical Application to a Case Analysis
In order to summarize and make the above data applicable, I will describe two case scenarios.

Case #1:

A 28-year-old worker fell off the roof, 2nd floor, while on the job. He suffered several bone fractures, head contusion and was taken to the emergency room. At the emergency room urine was sent to the lab for drug screening. Upon recovery from the injury the patient requested Workers Compensation benefits, and was denied since the urine drug screening utilizing EMIT methodology (immunological) detected opiates. In his deposition the patient testified that he has never used drugs, did not use drugs on the date of injury either. On careful review of the medical records, it turned out that the physician on behalf of the employer had recommended denial of the Workers Compensation benefits, failed to review the paramedic ambulance notes which was called to the scene of the injury and had transferred the patient to the hospital. The emergency room notes sheet indicated that the patient had received IV morphine from the medic driver to sedate him from his severe pain of bone fractures and skull concussion. The evaluating physician further failed to note that the urine sample was obtained 4 hours after the patient's stay in the emergency room, and did not specify whether that was a fresh urine sample, catheterized urine, and did not specify the volume of the urine. The patient's physician provided a report documenting that there is no history of drug abuse, there was no evidence that the patient was impaired from testimonies from his supervisors and coworkers on the date that the injury occurred, and has further provided evidence that the urinalysis was taken several hours after the patient was administered IV morphine by paramedics at the emergency room, and therefore, the results were essentially erroneous and irrelevant to the patient's cause of injury. This is an example of how drug urine testing can be applied wrongfully, and cause unnecessary pain, anxiety, delay of benefits and major expenses to the insurance carrier and the citizens who end up paying these expenses out of their pocket.

Case #2:

This is a 32-year-old female patient, a driver of a vehicle who was involved in a car collision and suffered internal bleeding (ruptured spleen), and a fracture of a bone of the lower extremity. She had requested medical benefits from her insurance carrier for medical expenses as well as time lost from work, and has filed a lawsuit since these were denied. The physician who examined the patient on behalf of the insurance carrier, and whose report was the basis for the denial, noted in his reports that upon admission to the emergency room on the date of injury, urine screening test for toxicology was done, and was positive for amphetamines. The physician who examined the patient on behalf of the insurance carrier failed to note the time of the testing, the time the urine was obtained from the patient, whether the patient was taking any medications which contain amphetamines, such as ephedrines or pseudoephedrines. The medical records examined carefully by the patient's physician, found notes from the house doctor who attended the patient at midnight on her admission. The house doctor took a good detailed history recorded in his handwriting which clearly stated that the patient is an allergic individual, and has for the last two weeks been using compounds which contain both ephedrine and pseudoephedrine. The physician who reported on behalf of the patient further was able to show in the medical records that all examining physicians clearly stated that the patient was alert x 4 on admission to the hospital, despite her pain and despite medications received from the paramedics and emergency room physicians. There was no clinical evidence of impairment, there was no history of drug abuse, there was no evidence of drug impairment. The problem with this case, is that the urine screening test was a false positive, because of the patient's use of over-the-counter ephedrine and pseudoephedrine containing medications to treat a cold and nasal congestion. Had a follow-up been done on that sample with gas chromatography/mass spectrometry showing a specific type of amphetamine, the story might have been different if indeed the patient was a user (which is not the case here). This case further illustrate: 1. The need for a very in depth evaluation of the chart and notes, as far as to the patient's mental capacity before and after the collision. 2. A detailed analysis of past and present prescription and over-the-counter medications. 3. The need to follow-up on urine screening test if it is positive for drugs of abuse in a case where such suspicion is indicated. Gas chromatography/mass spectrometry is the ultimate tool to eventually follow-up on such a suspicion.

In summary, while drug abuse and intoxication is a problem, the diagnosis of Aintoxicated@ is a scientific one and cannot be based on Apersonal beliefs@ or Afeelings@ of a defense examiner.

About Dr. Brautbar
Dr. Brautbar is board-certified in internal medicine, forensic medicine, and nephrology, with a specialization in toxicology. Dr. Brautbar has provided expert medical opinion and scientific evidence in product liability, personal injury, medical standards, and toxic tort cases throughout the United States. Dr. Brautbar is a Clinical Professor of Medicine at USC School of Medicine, Department of Medicine, and served as Chairman and Vice-Chairman of the Department of Medicine at the Queen of Angels/Hollywood Presbyterian Medical Center. He has published over 240 journal manuscripts, abstracts, and book chapters in the fields of internal medicine, toxicology, and nephrology. His resume includes past and present membership in 25 National and International Scientific Societies including the Collegium Ramazzini. Dr. Brautbar has been on the faculty of the National Judicial College and lectured to Judges on the issue of Scientific Evidence, and was a peer reviewer for the Federal Judicial Center (Reference Manual on Scientific Evidence, Second Edition, 2000). Dr. Brautbar has also been a peer-reviewer for the ATSDR.

Dr. Brautbar is a board-certified internist and nephrologist, and certified in forensic medicine. If you are interested in retaining Dr. Brautbar for forensic and expert witness testimony services, please submit the Contact Form.

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