How Far Can Hair Analysis Go Back?
Hair analysis is a new method of testing for the five most commonly used drugs--marijuana, amphetamines, opiates, cocaine and phencyclidine (PCP). This method of testing is more expensive than traditional urine analysis, but is also more effective in determining presence of toxins in the system and drug use.
The results found from a hair analysis are very accurate and can go back several months. Similar to a time line, it can show which toxins entered an individual's system, and when. Most standard hair analysis tests reflect drug use for approximately 45 days leading up to the test.
Hair for analysis is typically collected from the scalp. The sample size is normally 50 to 60 strands, and should ideally be cut one and a half inches from the scalp. The sample is sent to a hair analysis laboratory where it is liquefied and analyzed.
Hair analysis is not considered substantial evidence of drug use unless it is used in conjunction with some other test. The authority carrying out the testing may ask an individual to take a confirmation test, after a period, to corroborate or negate results of the first test.