Urine and Hair Follicle Drug Testing: Reality vs Myths
How far back in time can a urine drug test detect drugs?
A urine test can detect drug use as follows
- Alcohol (not EtG test): 6 - 12 hours
- EtG test for alcohol: up to 3 days,possibly 5 days for chronic heavy drinkers. The EtG test is controversial and may not be admissible in court if challenged.
- Barbiturates: 1 - 7 days
- Amphetamines, cocaine, ecstasy (MDMA), heroin and other opiates: 2 - 4 days
- Anabolic steroids: 2 -3 weeks for oral steroids; 1 - 3 months for injected
- Marijuana: occasional use: 1-6 days depending on amount smoked, individual body metabolism rates, and the cutoff level used by the test (15 ng/ml, 20 ng/ml, 50 ng/ml, 100 ng/ml).
- Marijuana: chronic or daily use: 7-30 days depending on the same factors listed above. Lower levels of Cannabinoids do remain in the body for longer than 30 days, but appear unlikely to result in a positive drug test due to cutoff levels.
- Crystal meth, methamphetamines: 2 - 4 days
How far back in time can a hair follicle test detect illegal drugs?
A hair follicle drug test can detect illegal drugs for approximately 90 days.However, it takes about 4-5 days from the time of drug use for the affected hair to grow above the scalp. Body hair growth rates are generally slower and cannot be utilized to determine a specific timeframe of drug use.
In general, how do drug tests work?
The human body creates metabolites as it digests or metabolizes food or drugs. A drug test looks for the drug itself and its metabolites. If drug metabolites are found, it means that person almost certainly consumed drugs.
How are urine drug tests performed?
The urine sample is taken using procedures to make sure it is really from the subject. The sample is labeled and then send to a laboratory. Most laboratories run a preliminary initial screening test called Immunoassay. If that first test is positive, it is confirmed by a second test using a more sensitive methodology.
How are hair follicle tests performed?
The human hair shaft is made up three layers. The inner layer is the medulla. The next layer is the cortex and the outer layer is the cuticle. The cortex makes up the majority of the shaft and is formed by tightly packed scales in an overlapping structure similar to roof shingles. The metabolites are deposited within the cortex layer as it feeds off the contaminated blood and grows.
How The Analysis Works: A sample can be obtained from any part of the body. This means shaving your head will not work as under arm or pubic samples can be used. The laboratory only considers the first 1.5" of hair from the root end. If a longer sample is sent, the laboratory cuts the hair to 1.5" to conform to the 90 day historical time period.
The sample is removed and cut it into very small pieces. This is soaked in a solvent that causes some of the metabolites to go into suspension. The solution is then placed in a centrifuge and separated. The sample is then subjected to analysis, the results are read and a conclusion made.
