« AlphaBiolabs Blog

Hair drug testing is considered the gold standard for providing a history of drug abuse and is routinely used in the forensic and family law fields. It is known as a ‘wide window’ form of testing as it can determine patterns of drug intake for up to 12 months.

There are two types of hair drug tests available: overview or segmented analysis. Head hair grows at an average rate of 1 cm each month; therefore, drug use can be established over a defined period depending on the length of hair selected.

An overview analysis is beneficial to obtain a general indication of drug use. This could range from 3 cm to identify drug use within that 3-month time period, up to 6 or even 12 months, dependent on the length of hair available. In an overview test, any episodes of drug taking are averaged out over the period being tested. For example, if an individual has not taken drugs for 5 months but then takes an excessive amount in 1 month, drug markers will be found along the entire length of the hair. In the case of segmented analysis, the episode of drug taking can be pinpointed to the actual month. Segmentation therefore provides a more detailed analysis.

In a 6-month segmented analysis, hair samples are sectioned into six measured segments of 1 cm to provide six individual monthly analyses. As such, segmented analysis is especially useful if you need to obtain a trend in drug use, such as to see a decrease or increase, or to highlight intermittent use.

Deciding on which type of hair drug testing to choose in legal cases can have major implications. If a 3-month overview drugs of abuse test is selected, even if an individual uses drugs occasionally, the test may come back positive for the whole 3-month period. This result implies that the sample donor had been abusing drugs during the whole period analysed.

To overcome this, segmented hair drug testing could be performed over the same 3-month period. The sample donor could show positive one month and negative the other 2 months. This would provide a more accurate assessment of the individual’s drug abuse/abstinence when presented to the court for scrutiny.

Cases such as this demonstrate the importance of expert advice when choosing the appropriate test to avoid misleading results.

A more in-depth version of this article can be read here.

AlphaBiolabs has a network of trained sample collectors able to take hair strand samples for free at its nationwide Walk in Centres. For expert advice on hair testing and other drug testing solutions, please call 0333 600 1300 or email us at