Head hair versus Body Hair: How accurate is body hair compared to head hair analysis?

A common question from clients when instructing us to perform hair analysis for evidence of drug use or chronic excessive alcohol use is; how accurate is body hair compared to head hair analysis?

1. The laboratory analysis performed at Cansford Laboratories is exactly the same whether we analyse head hair or body hair, so in simple terms the accuracy of the end result is the same for both head hair and body hair samples.

2. However, when we look at the time period covered by each hair type, the approximate time period covered by a head hair test is much more representative than when compared to an equivalent length sample of body hair.

Both head hair and body hair grow at a reasonably constant rate of 1 cm per month, with a range of 0.7 to 1.5 cm per month. However, only head hair can be cut into sections to produce a historical picture/pattern of drug use over monthly time frames, because of the biology of the hair. It has been estimated that for body hair, 40 – 60% remains in the resting (telogen) phase in comparison with the 10 to 15% found in head hair. During the resting phase, hair is not growing but does contain traces of drug from previous use. Because body hair contains a larger proportion of hairs in the resting phase in comparison with head hair, if a 3 cm sample of body hair was to be analysed, the period covered by this test would potentially be much longer than an equivalent length head hair sample.

Due to this, it is more difficult to determine the period of drug exposure when testing body hair, in comparison to head hair. Calculation of the window of detection for body hair is based on the length of the tested sample, with an average growth rate of 1 cm/month, but in practice, the period covered by the sample represents a period 2 to 3 times longer because of the biology of body hair.

3. Choosing which hair type to analyse can be a difficult decision, and it is often useful to discuss this with the laboratory. Here are some scenarios:-

  • A hair test is ordered to cover a specific time period and head hair and body hair is available – head hair should be used.

  • A hair test is ordered to cover a specific time period and head hair in not available – body hair should be used.

  • Sectional analysis is required to demonstrate that an individual has decreased their use of drugs – head hair should be used.

However, there are going to be times when body hair is the only option, in this situation it is of paramount importance to deal with a company where you have rapid and easy access to the people that can help out. At Cansford we will listen to your requirements and will advise the best method that will be more appropriate to your needs.

If you would like any further information on the best hair type to use or any other matter, please don’t hesitate to contact us on 02920682031 or info@www.cansfordlabs.co.uk .

 

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