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Safeguard OSH Solutions - Thomson Reuters

Safeguard OSH Solutions - Thomson Reuters

Alert24 - Safeguard Update

Saliva testing standard

Saliva testing standard
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Publication Date:
New Zealand

A new Standard setting out procedures for the detection of drugs in oral fluids will allow workplace drug tests that provide a better indication of fitness for work, according to a member of the Standards Committee working
on the draft.

CK Rahi, operations director of Advance Diagnostics NZ, told Safeguard that although urine sampling is currently the preferred testing method in New Zealand, drug residues found in urine could be at least four hours old, and possibly much older.

"Metabolites in the urine do not occur straight away and can take up to four hours to be detected in the urine specimen," she says. "You're missing the initial window - the first few hours when somebody can be impaired by the drug - so this new Standard opens up a whole new chapter."

Saliva testing provides a more reliable way to assess recent drug use and - because it will not detect substances that have been used more than a few hours before the test is conducted - it also removes the potential for privacy issues.

Australia developed a Standard to regulate saliva testing more than a decade ago, and the practice is widely used across the Tasman, but Rahi says that until now New Zealand has been lagging behind.

She expects this to change when the new Standard - an updated version of the existing Australian Standard 4760 known as AS/NZS 4760: 2017 - is adopted, which will probably happen later this year.

"We've been working on the project since July 2015, and the first draft went out for public comment in March this year," she says. "We're currently editing the final draft, which will again go out for comment for six weeks, to
ensure there are no unresolved issues before it is finalised."

Rahi says the Standard will address one of the principal issues with current saliva testing regimes by specifying clear cut-off levels for drugs of abuse, particularly cannabis.

"In the 2006 Standard there isn't a clear cut-off point for detection - just a target value," she says. "For THC, for instance, this is 25 nanograms per ml, which is too high to detect acute intoxication and may result in false negatives when people are actually impaired."

While Rahi can't disclose the cut-off figures that will be used in the final draft until the document is available for public comment, she says the first draft brought the cut-off for cannabis down to 10 nanograms per ml.

The absence of defined cut-off points has also made it difficult to get testing devices certified, but the new Standard will give clarity in this area.

"Having a fixed cut-off point builds in a bit more accountability on the part of those wanting to implement this method, because it means testing devices will be able to be certified."

New Zealand's accredited laboratories do not currently offer confirmatory testing for oral fluid samples, so saliva testing will be available only for screening purposes - at least initially. However, Rahi says that if urine specimens are only used to confirm non-negative results, it will significantly reduce the need for invasive testing, although she cautions that those choosing to adopt oral fluid screening should do their due diligence to understand the sensitivity, specificity and accuracy of the device they choose.

The new Standard is expected to be completed before the end of the year.

People Mentioned:
C K Rahi
Organisations Mentioned:
Advance Diagnostics
Reference No:

From Alert24 - Safeguard Update

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