False Positives in Drug Testing
Certain preliminary "screening" tests commonly used by police in field testing (example: immunoassay) for possible drug use are NOT SPECIFIC for marijuana, cannabis or the metabolites (burn-off substances produced as your body eliminates the drug). The standard police "THC test" is a one-step rapid, qualitative immunoassay for the detection of tetrahydrocannabinol compounds in urine. The cutoff concentration for a positive result in an immunoassay test is 50 ng/ml as recommended by the Substance Abuse and Mental Health Services Administration SAMHSA) (NIDA). To truly determine whether the suspected "drug" was from marijuana or cannabis, a SECOND, more sophisticated test must be conducted. This is called a gas chromatograph/mass spectrophotometer test (GC-MS). This device permits IDENTIFICATION and QUANTIFICATION of specific amounts of cannabinoids that are ONLY produced when cannabis or marijuana has been used. The cutoff for GC-MS is 15 ng/ml, according to the Substance Abuse and Mental Health Services Administration (SAMHSA) (NIDA).
Substances or Health Conditions that can cause false "marijuana" positives:
OVER-THE-COUNTER DRUGS
Ibuprofen: (Advil®, Nuprin®, Motrin®,
Excedrin IB® etc)
Naproxen (Aleve®)
Ketoprofen (Orudis KT®)
Riboflavin (B2, Hempseed Oil)
Visine® eye drops - ["Visine caused false negatives (EMIT d.a.u. assays)
in the tests for benzodiazepines, but did not change the test results for
amphetamines, barbiturates, cocaine, or opiates."] <http://www.erowid.org/psychoactives/testing/testing_info11.shtml>
PRESCRIBED
DRUGS
Promethazine (Phenergan, Promethegan)
Dronabinol (Marinol®)
HEALTH
CONDITIONS
Liver
Disease
Kidney infection (Kidney disease, diabetes)
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