Drug Testing Information

402 W. County Rd. D
St. Paul, MN 55112
Hair Analysis
American Toxicology Institute, Inc.
3330 Sunrise Avenue
Suite 110
Las Vegas, NV 89101


Drugs (except THC):
The best time to take a urine sample is within 2-4 hours after drug ingestion. Testing any sooner than about an hour after drug use enhances the risk of missing urinary drugs because they have not had sufficient time to enter the bladder. After approximately 12 hours following intake, the urine levels of some drugs begin declining. This decline continues until the levels are no longer detectable. As a general rule, detection time of most drugs (except THC) in urine, after usage has stopped, is as follows:

1 Day Should always be detected.
2-3 Days Detected in most individuals. Some would be negative.
4-5 Days Detected in some individuals. Most would be negative.
6-7 Days Detection is rare.

The retention time of urine alcohol is much shorter. While 8-12 hours is the average time alcohol can be detected in urine after ingestion, the time can be as short as only 4 hours, or as long as up to 24 hours, depending on a variety of conditions.

Marijuana (THC), being highly fat soluble, needs to be interpreted according to its level, rather than its presence. Small amounts will linger in the body for weeks, or even months. Generally, one marijuana cigarette will produce approximately 200-600 ng/ml of THC metabolite in the urine. Chronic users can have over 1000 ng/ml., and up to 6000 ng/ml. For a chronic user, the decline in levels of THC is slower than occasional users. It may require 2-3 weeks to get below 100 ng/ml. Therefore, if a urinary level of of 75 ng/ml was reported, it may represent: an occasional user who stopped usage 2 or 3 days prior; a chronic user who stopped usage 2 weeks prior; or an individual taking 1 or 2 “hits” of a marijuana cigarette within the last 24 hours.

The quality of the marijuana inhaled is another factor affecting urinary levels. Generally, marijuana cigarettes contain 1/2 to 1% THC (0.5-1.0%). However, if an individual were to smoke a poor quality cigarette, only 0.1% or less THC, he may never get over 100 ng/ml. On the other hand, there is a high quality marijuana available, which is up to 14% THC. One cigarette of this type may push urine levels over 1000 ng/ml.

Hair Analysis

Hard Drugs (except THC):
Hair follicle testing is performed for what is termed as the “hard drugs”…Cocaine (Crack), Phencyclidine (PCP), Heroin (as Morphine), and Methamphetamine (Speed). Because marijuana (THC) does not accumulate well in the hair, the false negative rate for this drug in hair is high. As a consequence, ATI suggests testing a urine specimen for THC, which generally stays in urine much longer than the other drugs. The hair sample consists of approximately 90 days growth (1-1/2 inches), cut directly from the scalp. In cases where scalp hair is not available, hair from the chest, beard, arms or other body areas may be substituted. Ingestion in normal amounts of any of the tested drugs during the last 80 days of this period would result in a positive finding.

Because it takes approximately 7-10 days before drugs appear in external hair, recent ingestion would not be detected. For this reason, hair testing is recommended for pre-employment testing. Probable cause or post accident testing should be performed on urine and/or blood samples. However, parallel hair testing could be performed in these cases to investigate past usage.

The procedure for testing the hair involves weighing, washing, liquidation, extraction, and screening. If the screen is positive, the analysis is repeated using a second section of hair and a second, more specific confirmatory method. Typically, after the hair is thoroughly washed, confirmation proceeds with Gas Chromatography/Mass Spectroscopy (GC/MS). While negative results are generally reported the day following receipt, positive results take an additional day, due to the extended confirmatory testing.

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