Toxicology tests on hair are performed to determine if a person has used drugs or pharmaceuticals at an earlier time.
Head hair: Head hair grows at an average rate of about 1 to 1.5 centimeters per month. Each 1 to 1.5 cm of hair represents a 1-month history of drug use. For example, an 8 cm long tuft of head hair contains 8 to 12 months of drug consumption history.
With the toxicological analysis of the hairs we can investigate previous periods of consumption and at the same time determine the profile of the user: occasional user, daily user, etc., while for most drugs and pharmaceutical substances the exact amount of consumption per week or month can be determined.
Hair sampling can also be done from other parts of the body such as the armpits, genitals, sternum, hands, beard, etc., also providing information on past use, but without being able to determine the exact time period of consumption of the substances because the rate of hair growth at these sites is not specific.
Toxicology tests on hair
Detection window: from 7 days – up to years (depending on hair length) It takes about 7 days for a substance to be detected as it has to be broken down in the body and transported to the hair via the bloodstream.
Types of hair analysis: Total and segmental analysis.
Segmental analysis of head hairs is the most detailed method of detecting drugs in hairs. By cutting head hair into 1 cm sections, the use of one substance per month can be determined and a detailed profile of the consumption history can be obtained. In addition, segmental analysis is useful in cases where a trend in use needs to be determined, for example an increase or decrease in the use of a drug substance over time or to confirm discontinuation.
The overall analysis of head hair (for hair toxicology tests) provides an overview of the use of a drug substance over the period of time to be tested. Each analysis covers a period of 3 months and depending on the length of hair available the last 3, 6, 12 months or later can be examined.
Sample collection For the analysis, between 15 and 200 hairs (depending on the type of analysis to be performed) of at least 1 cm in length need to be collected.