False Positives in Drug Field Testing Kits

The director of a lab recognized by the International Association of Chiefs of Police for forensic science excellence has called field drug testing kits “totally useless” due to the possibility of false positives. In laboratory experiments, at least two brands of field testing kits have been shown to produce false positives in tests of Mucinex, chocolate, aspirin, chocolate, and oregano. However, law enforcement agencies continue to employ these kits.

Fox 13 Tampa investigated the validity of drug field testing kits in the wake of arrests of three people based on false positives from field tests. Eventually all three were cleared and all charges were dropped. However, for the months between arrest and confirmatory testing by the state crime lab, the individuals felt that they were “guilty until proven innocent.”

Dr. Omar Bagasra, a research scientist at Claflin University, has been looking into the validity of field drug testing kits. In controlled tests in his laboratory, Dr. Bagasra, Dr. Cherilyn Haggen-Paey, and forensic scientist Chris Addanki, have demonstrated that the chemicals used in the kits are prone to give false positives even with common household materials. According to their tests, Mucinex can produce false positives for heroin and morphine; chocolate can be interpreted as marijuana; and soap can test positive as GHB. Even exposure to air caused false positives in some kits, according to their tests. The scientists noted that they had trouble interpreting results in a laboratory environment and “you can imagine in the field it’s even more difficult.” However, the experts say the problems are not linked to just the individual kits tested or a specific manufacturer, as many the field test kits tend to contain the same chemicals.

Field drug testing kits were created to screen for illicit substances in the field followed by more complete testing in a laboratory setting. However, the tests stand in for more scientifically valid testing until analysis at state crime labs occurs. Drug testing at state crime labs is typically performed just prior to trial due to the high rate of plea bargaining in drug cases, and therefore false positives are often not discovered unless contested at trial. During this time, the false positives from field tests can cause innocent citizens to be detained in jail for weeks or even months.

“False Positive Equal False Justice,” a 2008 report created for the California Attorneys for Criminal Justice, noted that false positives resulting in criminal charges has been an ongoing problem. In 2003, a Pennsylvania college student was held for three weeks when flour was mistaken for cocaine. In 2007, musician Don Bolles was arrested for possession of GHB which was actually soap. Additionally the report lists approximately forty extracts—such as vanilla, peppermint, or ginkgo—which can test as false positives for marijuana.

Dr. Frederic Whitehurst, a Ph.D. chemist and former FBI lab supervisor, has expressed concern with the use of field drug testing kits. He stated that he has “no confidence at all in those test kits.” Due to the high chance of false positives, both Dr. Whitehurst and Dr. Bagasra have recommended that drug field testing kits not be used. They say law enforcement would receive more valid results by waiting for results from lab testing. The kits are single use and range from a $4 to $20 a use depending on what drug is being investigated.

For more general information on forensic drug analysis see http://www.ncids.com/forensic/drugs/drugs.shtml.

Click here to read an article about the 2011 arrest of a man in Buncombe County based on a false positive field test result of cheese and tortilla dough.


Filed under Drug Analysis/Toxicology

2 responses to “False Positives in Drug Field Testing Kits

  1. Great article. This video vividly shows just how inaccurate NIK tests can be: https://www.youtube.com/watch?v=djXVnmrlKvE

  2. Annod

    I’ve been looking into this subject ever since I have been testing positive for not just the diazepam I take by prescription for a valid medical reason but also two other benzodiazepenes which I do not take! This has happened most weeks I have had the drug test done on me. I am on Suboxone treatment for becoming chemically dependent on pain meds and I have always made a point of being totally honest with my Suboxone doctors. I personally have no reason not to be. Yet I have never seen so much paranoia and distrust among these types of doctors and a therapist who I’ve had. It’s been extremely painful and insulting to be treated like a lier, not only because of these test results but also for no reason at all! I finally found an article that showed that those two other benzos can show up as false positives for people taking valium, and the doctor said he believed me when he read it. But now he is going to do another type of test. Even though that shows he actually doesn’t believe me (which is fine-at least he has always been for the most part respectful in spite of his doubts, and at least he has a reason), then if it is an accurate test I will be satisfied and relieved. But now I am afraid of all these tests. Does anyone know of any info for the lay person (and their doctors who don’t know what they’re doing) to navigate with? Or does anyone know of tests that are fool proof that I can ask for should my test(s) turn out false positive again? (I am aware that the mix of Subs and diazepam is not safe for people who either overdose on one or both or who are not used to one med or the other, but I have been on diazepam for 25 yrs and the Sub for between 5-8 years. I am not dead, and even if there was a tiny chance of death I would choose to take that chance, as the diazepam for my medical condition-not anxiety, a physical condition- is the only thing that works and makes my quality of life significantly better).

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