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Overview or Segmented

Overview Or Segmented Hair Analysis

Why test head hair?

Hair samples provide a unique record of the drugs someone has taken over a period of time.  Head hair typically grows at approximately one centimetre per month and as it grows, any drugs that have been consumed, together with their breakdown products (metabolites) can be incorporated into the hair.  Each centimetre of hair reflects approximately one month’s history of drug use (or non-use), with the section closest to the scalp being the most recent.  In the laboratory our scientists can access this drug history and interpret and report the findings.

Urine and oral fluid testing can reveal drugs that a person has consumed in the past couple of days, but only hair testing can provide us with a ‘wide window’ (several months or potentially years) of detection for drugs and their metabolites. 

Segmented or Overview?

We can investigate an individual’s drug use with either an ‘overview’ hair analysis or a ‘segmented’ hair analysis. There are advantages to both and the type of testing you require will always be specific to your particular case. Cellmark’s customer service team can help guide you through the process and advise the best possible testing for your case.

An overview analysis provides an ‘average’ of a number of months grouped together.  For example, if you simply want to know if someone has taken drugs within approximately the last three months, we would analyse a single 3cm section of the most recent hair growth.  Because this is a single sample it is very cost-effective.  If the result is positive for a drug or drugs, this will indicate usage during the months prior to sampling but we would not be able to tell you in which of the three months the drug(s) had been taken.  Overviews may also not detect low level or infrequent irregular use, as these would be potentially ‘diluted’ within the time period we are investigating.

By segmenting head hair samples into monthly 1 cm sections, a month-by-month historic profile of drug use can be obtained. For example, if someone has reported that they took drugs 6 months ago but has not taken any since, this can be explored by taking a 6cm section of hair and cutting into 1cm sections. We would then analyse each as its own individual test and report the results for each section to provide a picture of drug use or abstinence trends.

Overview or Segmented Hair Drug Testing Explainer

If no head hair is available for testing, we can of course analyse body hair.  However, the variability in the growth rate of body hair means that we can only reliably provide an overview analysis of recent drug use, rather than segmental testing.

Can testing determine the exact date and time that drugs were taken?

Analysing head hair can provide a unique and detailed insight into an individual’s pattern of substance misuse; however, it can only say whether a drug was taken within the approximate time period that has been tested for, not the exact date or time of day.

Cellmark is an experienced and accredited provider of Drug and Alcohol testing for Local Authorities and Family Lawyers as well as for the police, coroners and the courts.  We pride ourselves on our high-quality standards and our customer support.  Our experts are always on hand to provide advice, discuss results and to address any queries you may have.

For expert advice on which drug test is best for your client, call our friendly Customer Services team on 0800 470 2529 or email and a member of the team will be in touch.