Frequently Asked Questions7
7 – What are hair tests? 
Over 300 drugs have already been extracted from hair, but the standard analysis which is carried out is for the standard drugs—cocaine, amphetamines, methamphetamines, cannabis, opiates and PCP.
Drugs in the bloodstream get trapped in the hair shaft as it grows in the root follicle. Since hair is inert protein, the drugs remain trapped there until the hair is cut. About a week after drug use the hair has grown enough to be cropped close to the scalp, providing the perfect history of drug abuse.
The drugs cannot be washed out or affected by chemicals because they remain locked away in the centre of the hair, known as the hair cortex. Even perm solution or bleaching will not affect the hair core.
The process has been proven in a court of law many times, and strict procedures are adopted to prevent surface contamination, ethnic differences, or variations in hair growth rate. The usual sample is tested for a three month history, but tests can be done month by month if needed. Just a small snippet of about 50 hairs are used, to a special procedure which avoids any signs of hair being taken from the donor.
Other FAQs