During the last couple of years drug screenings in hair samples have been rapidly gaining recognition. In average, head hair grows about 1 cm per month. Following the consumption of alcohol or drugs of abuse, active substancesand their metabolites are continuously incorporated and deposited into the hair matrix. Depending on the analysed hair segment, a previous drug consumption can be detected. A3 cm long hair segment for example will roughly cover a period of 3 months time. Monitoring a long lasting abstinence from drugs is also possible, depending on hair length.
The collection of hair samples is straightforward and non-invasive and can easily be sent to the laboratory as no pre-analytical precautions are necessary.
Hair collection should be performed by a qualified collector, who must not necessarily be a medical professional.
It must be noted that a single or occasional consumption of drugs may not be detected in hair samples. Moreover, hair growth is not continuous. After a growth period (anagenic phase) follows a rest period (telogenic phase). This explains why a 3 cm long hair segment does not exactly correspond to a 3 months period but can cover a much longer period of time.
Particularly at the beginning of an abstinence control programme a safety margin of several months should be added to avoid a detection of drugs originating from a previous period of drug consumption.
Depending on the question the following substances and substance classes could be analysed in hair samples:
- Screening for psychotropic Substances