P5: Hair analysis in the workplace: Global harmonisation required

Abstract

The main benefit of using hair as a sample for drugs of abuse is the longer window of detection and hence the greater sensitivity for detecting drug use. The identification of a non-drug user or drug use over an extended period is much more probable with hair testing when a prospective employee applies for employment. The purpose of this study was to compare the requirements, sample collection and results obtained from the analysis of drugs in hair samples in the workplace sector in 3 different countries: Brazil, UK and Australia. The aspects regarding test requirements, sample collection and test results will be compared. Hair samples from the workplace sector for pre-employment and in-employment were received in our laboratory in the UK for analysis. All samples were extracted and analysed by LC-MS/MS using methods accredited to ISO/IEC 17025 standards. The substances targeted included: amphetamines, benzodiazepines, cannabinoids, cocaine, opiates, opioids (UK, Brazil and Australia samples), ketamine (UK samples) and PCP (Brazil samples). The length of head hair samples were analysed according to clients’ requests for period of detection and the whole length of body hair samples were analysed. Hair samples from Brazil (N=630) were largely body hair (87.6 %), mostly leg hair (56 %) and axilla hair (24 %). The majority of samples collected in the UK (N=1321) and in Australia (N=862) were predominantly head hair, 88.7 % and 92.3 %, respectively. Samples from Brazil were exclusively for pre-employment whilst samples from the UK and Australia were a combination of preand in-employment cases. The window of detection requirements for samples from Brazil varied from 90 to 180 days and up to 365 days in the case of all body samples. A 3-month window of detection was typical for samples from the UK and Australia. The mean length of all body hair samples analysed was 2.5±0.9 (mean±sd, n=2813). Drug detection rates in the samples from the UK, Brazil and Australia were 3.2 %, 2.1 % and 9 %, respectively, being Codeine (1.7 %) and Cocaine (0.7 %) more commonly detected in the UK, Cocaine (1.4 %) in Brazil and Cocaine (5.2 %) and MDMA (4.5 %) in Australia. Of the positive samples, the detection of one drug was predominant, with 93 % in the UK, 82 % in Brazil and 68 % in Australia. In the latter country, 2 drug groups concomitantly, cocaine and amphetamines, were detected in 27 % of the samples. Ketamine was only tested in the UK and detected in 4 samples (0.3 %). Whilst the utilization of head hair is always recommended in workplace testing, the extraordinarily high proportion of body hair samples received from Brazil is likely to be the result of a misconception that any body hair can cover a period of detection of a year. Because of its biology, the detection period covered by body hair is 2 to 3 times longer than head hair, and it would cover a whole year provided its length was a minimum of 4-5 cm. Since the mean length of body hair is approximately half this length, the assertion that body hair covers a period of 365 days is misleading. 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. Regulated procedural guidelines regarding substance abuse testing in hair could improve the service provided by drug testing laboratories.