Testing times

The
UK guidelines for drug and alcohol testing are essential reading for anyone
involved in the testing process and should be used as a template for best practice

It was the US which first grasped the need to introduce drugs testing in the
workplace. President Ronald Reagan issued Executive Order No. 12564 on 15
September 1986 requiring drug testing to be undertaken by all federal employees
in safety and security positions

The American Department of Health and Human Services published the first
guidelines on workplace drug testing in the Federal Register in April 1988, and
under SAMHSA (Substance Abuse and Mental Health Services Administration)1 these
are regularly reviewed.

US guidelines

The US guidelines specify the drug groups that should be included in a
primary screen, the screening cut-off levels, acceptable methods of
confirmation and concentrations together with a range of other issues relating
to the chain of custody specimen collections.

These guidelines have been adopted by a number of countries prior to
developing their own. Some of the standards that have since been developed
differ in many respects from those in the US. For example, the Australian/New
Zealand Standard2 minimum drug profile includes benzodiazepines but not
phencyclidine (PCP) which is rarely encountered outside the USA, and secondly,
gas chromatography/mass spectrometry (GC/MS) and high performance liquid
chromatography (HPLC) are acceptable as screening techniques as well as a
confirmation techniques. There are other differences not documented here.

UK guidelines

In 2000, the UK guidelines were developed by an expert group with wide
experience of workplace drug testing in this country. They represent an
overview of best practice for laboratories providing workplace drug testing
services within the UK. The guidelines are designed to ensure that the entire
drug testing process is conducted to give accurate and reliable information
about a donor’s drug use.

All laboratories that undertake legally defensible workplace drug testing
within the UK should use the guidelines as a template for accreditation. The
United Kingdom Accreditation Service3 (UKAS) has been approached as the most
suitable body to undertake this.

The first set of guidelines focuses on the analysis of urine, which has long
been accepted as the most useful specimen for drug testing.

The UK guidelines have four main objectives:

– To provide a minimum set of criteria for the providers of workplace drug
testing services within the UK

– To ensure that the processes undertaken are capable of legal scrutiny

– To provide safeguards to protect specimen donors

– To define for laboratories common quality assurance and quality control
criteria that are capable of being accredited by an external body.

Within the guidelines, a number of key stages of the workplace drug testing
process have been considered:

Specimen collection

Urine specimens for legally defensible drug testing need to be collected
under circumstances that respect the dignity of the individual while ensuring
that the sample is fresh and has not been tampered with in any way. The
appendix of the UK guidelines contains an example of a typical protocol for
urine collection. This provides advice on how to maintain the integrity of the
specimen by monitoring its temperature and making direct observations.

An important aspect of specimen collection is gaining informed consent. It
asks donors to confirm their personal details and that the collection process
has been undertaken correctly.

Laboratory analysis

On receipt of a sample at the laboratory, initial checks are made on its
chain of custody and appearance. If the sample passes these checks a portion is
taken which goes through an initial screening test for the presence of drugs.
Further testing of the validity of the sample may also take place at this
stage.

If the screen results are negative no further analysis is undertaken.
However, if they indicate the presence of a drug (above a predefined cut-off
level) a confirmation test to prove or disprove its presence must be carried
out on another portion of the sample.

Interpretation of results

A positive result on analysis may be due to medication (prescribed or
over-the-counter) or to a dietary cause. An essential part of the drug testing
process is the final review of positive results.

Interpretation is best carried out by a qualified medical practitioner, also
known as the medical review officer, who can consult with the laboratory
toxicologist, the donor and the donor’s GP.

Quality assurance

Drug testing laboratories must have a quality system that encompasses all
aspects of the testing process such as sample receipt, chain of custody,
security and reporting of results, and screening and confirmation testing.

Quality assurance procedures must be designed, implemented and reviewed to
monitor the conduct of each step of the testing process. The standard set by
ISO 17025 must apply.

The laboratory must be accredited for workplace drug testing by a recognised
external accreditation body, preferably UKAS, and must be working to standards
set by the UK guidelines.

Additional guidelines are being developed to cover alcohol testing in a
range of other biological samples, and drugs in oral fluids, hair and other
sites.

Methods have now been developed to assay drugs and alcohol in oral fluids,
as well as in hair and the precise role of these alternative biological
matrices in drug testing is under investigation. Additional guidelines are
being developed to cover these alternative biological samples.

As of November 2001, it was agreed that the UK guidelines would form the
basis of the European guidelines. These latter guidelines would be a statement
of common standards and principles, leaving each country free to adapt the
appendices (cut-off levels, methodologies and so forth) for their own
requirements and to meet national legislation.

There is a proposal that these European guidelines4 could provide the basis
for a one-day workshop, to be held in autumn 2002.

References

1. www.samhsa.gov

2. http://www.standards.com.au

3. www.ukas.com

4. http://www.ewdts.org

Other relevant websites

http://www.wdtforum.org.uk   http://www.tiaft.org

Helen Vangikar is consultant toxicologist at OmniLabs Limited

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