Drug testing using hair samples is an essential test where safety and security really matters. It is particularly useful since the long window of detection enables drug users to be excluded when their drug use would be incompatible with their activities, were they to be employed. Employers, however, need to be adequately informed about the advantages and limitations of hair drug testing from their perspective, such as when to use it, what drugs to test and which hair sample, whether head hair or body hair.
When use hair drug testing
The diversity of requirements from employers varies between the countries. For example, samples from Brazil were exclusively for pre-employment, mostly of body hair samples, whilst samples from the UK and Australia were a combination of pre- and in-employment cases, mostly of head hair samples. A 3-month window of detection was typical for samples from the UK and Australia.
Drug patterns varies between countries
Drugs tested and detection rates in the samples from the UK, Brazil and Australia were different, with codeine and cocaine more commonly detected in the UK, cocaine in Brazil and cocaine and MDMA in Australia. Ketamine was only tested in the UK and detected in a few samples.
The requirement for international guidelines.
A typical example where sectors or countries would benefit from international guidelines is the requirement in Brazil, where it is common the request of hair analysis for a “window of detection of 365 days”. with unrealistic drug panel requirements, and the assumption that it is possible to correlate the levels detected in hair samples with the amount of drug consumed, highlighted the need for adoption of international guidelines.
Providing Appropriate and Meaningful Workplace Hair Drug Testing
Workplace drug testing is a complex interdisciplinary science, with the choice of the sample to use in drug testing depending on the purpose of the testing. Where it is necessary to ensure that no employee is working under the influence of drugs, drug testing using urine and saliva (oral fluid), including blood samples in case of accidents, is more appropriate. The ability to identify what drugs were used over a long time frame is one of the key advantages of hair analysis for pre-employment and workplace testing.
As different countries and services use hair testing as a tool to prevent recruitment of drug users, there would be benefits in standard criteria and a realistic drug panel, representative of the general population’s drug use habits. Procedural guidelines for drug testing using hair samples do exist, covering sample collection, advice as to the most suitable analytical procedure and even guidance as to best practice interpretation. However, these guidelines are largely directed at laboratories.
There is a need for laboratory best practice guidelines to be distributed to employers and other clients, as the demands of marketing and sales departments tend to obscure the messages coming out of laboratories. The guidelines need to ensure that no user, whether an individual or a large organisation, can misunderstand what the technique can deliver.
The paper above was presented at the 20th Meeting of the Society of Hair Testing (SoHT) in Sao Paulo, Brazil last May– and discussed in chapter “Workplace testing and screening programs on large populations” of the newly published book “Hair Analysis in Clinical and Forensic Toxicology“