How does a forensic toxicologist test hair for drugs?

How does a forensic toxicologist test hair for drugs?

When an individual takes a drug into his or her body, a portion of that drug becomes attached to the root structure of human hair. As time goes on, as the hair grows - and hair grows at the rate of about a half an inch a month - that drug remains embedded in the hair. At some point, a hair will be removed from the body if indeed we are interested in testing that hair for the presence of the drug. The hair will be extracted for drugs and tested by various analytical techniques that are available in the toxicology laboratory. The important thing to remember is that we can, we being the forensic toxicologist, detect the presence of drugs in the hair long after the intake of that drug. For example, if you have a hair length of five inches in length, that means that we can detect the hair up to ten months after intake.