Workplace drug testing standards, explained

Last verified: 2026-07-29

Your testing program is only as defensible as its weakest procedural link — and the standards are where those links live.

The three standards that matter

• AS/NZS 4760:2019 — oral fluid. The current saliva standard, with a THC screening cut-off of 15 ng/mL — lower than the 25 ng/mL in the superseded 2006 edition. Oral fluid skews toward detecting recent use and is now roughly as common as urine in Australian workplaces.
• AS/NZS 4308 — urine. Detects THC metabolites over longer windows — days, and longer in frequent users. Says more about history than about the shift ahead.
• AS 3547 — breath alcohol. The alcohol side of the program; included here because policies and devices are usually procured together.

The traps that turn into evidence against you

1. Standards mismatch. In a 2025 coal mining dispute, workers’ site self-test kits were aligned to the 2006 standard’s 25 ng/mL cut-off while formal testing used 2019’s 15 ng/mL — a worker could pass his own kit and fail the real one. Whatever you deploy, deploy one standard, name it in the policy, and match the kits to it.
2. Screening treated as proof. On-site devices are indicative. Confirmatory laboratory analysis before disciplinary decisions is both good science and the procedure tribunals expect; skipping it converts a winnable case into a procedural loss.
3. Procedure drift. Unsealed kits, results read outside validity windows, altered paperwork — all argued in recent proceedings. Chain-of-custody discipline is not bureaucracy; it is your evidence.
4. Prescription-blind interpretation. A confirmed THC result from a disclosed, assessed prescription is a different management problem than a concealed one. Your procedure should route results through whoever holds the disclosure records — with a medical review step where results need clinical interpretation.

Choosing between oral fluid and urine

There is no universally right answer: oral fluid correlates better with recent use and feels fairer to a prescribed workforce dosing away from shifts; urine casts a longer net and suits some risk profiles and industrial instruments. What matters legally is that the choice is deliberate, named in the policy, applied consistently, and matched by the actual devices and laboratory arrangements on site.