Hair Tests
Are currently several times more expensive than urine tests (~$100-$150).
Are considered a relatively unintrusive method of drug testing.
Detect substance use over a longer period (see detection period).
Do not usually detect use within the past week.
Require a sample of hair about the diameter of a pencil and 1.5 inches long. They can not be done with a single hair.
Test positive a little more than twice as often as a urine test. In a recent study, out of 1823 paired hair and urine samples, 57 urine samples tested positive for drugs of abuse; while 124 hair samples from the same group tested positive.
Are not significantly affected by brief periods of abstinence from drugs.
Can sometimes be used to determine when use occured and if it has been discontinued. Drugs, such as opiates (codeine, morphine, heroin) lay down on the hair shaft very tightly and are shown not to migrate along the shaft, thus, if a long segment of hair is available one can draw some "relative" conclusions about when the use occurred. However cocaine, although very easy to detect, is able to migrate along the shaft; making it very difficult to determine when the drug was used and for how long.
Claims to be able to reliably differentiate between opiate and poppy seed use.
We've heard that many hair tests now check for more than the NIDA 5, and include at least Cannabis, Ecstasy/MDMA, Cocaine, Opiates, Methamphetamine, Amphetamine, Phencyclidine (PCP), Benzodiazepines, & Barbiturates (2001).
