Hair testing is considered accurate and can go back as far as 90 days. As hair grows out, any drugs used are encased in the hair shaft, so the longer the hair, the more time back in the individual's drug history the laboratory can detect. Human hair grows an average of .5 inches/month, which corresponds to 30 days of possible drug testing for every .5 inch. Testing laboratories generally require 1.5 inches for testing. This means they can test for around 90 days of drug use. This time period depends upon the rate at which the individual's hair grows of course. Some people attempt to circumvent this through shaving their heads. This does not usually work. In the absence of the required amount of hair on the scalp, body hair can be used as an acceptable substitute. If all hair is shaven, the follicles of the hair may be used in place of the hair. Removing the hair follicles is more painful.
Additionally for pre-employment hair testing, the inability to obtain a sample may be grounds for not hiring the individual. Hair Testing labs are regulated by CLIA or SAMHSA (not FDA). There is a growing trend in major companies and law enforcement agencies to utilize hair analysis on account of its efficiency and reputation as the gold standard when considering test accuracy. This technology makes use of radioimmunoassay or the more modern ELISA technology with subsequent confirmation by mass spectrometry.
In recent years, hair testing has been the subject of a number of lawsuits. Studies have shown that different ethnic groups have different hair structure, potentially leading to false positives. Our Clear Choice Hair Follicle Shampoo is available to help you pass.