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Drug testing involves using urine, hair, saliva or blood samples to detect if a drug has been used within a certain timeframe. But drug testing doesn't measure how impaired someone is. 

Workplace drug testing does not always improve workplace safety, can be ineffective at managing impairment, and is highly invasive.

Drug testing can include:

  • pre-employment drug testing
  • random drug testing, though New Zealanders can only be randomly drug tested in safety sensitive work environments
  • testing on suspicion of drug use
  • testing if there is an accident or incident
  • regular drug testing, such as in courts, health monitoring or for athletes

Many drug tests don't detect the presence of the actual drug. Instead, they detect the substances that the body breaks the drug down to (called metabolites). 

There are limitations to drug testing: 

  • It's impossible to test for every drug
  • Some medications can cause false positives
  • Drug testing only detects previous use of drugs, not whether someone is currently impaired or affected by drug use
  • Requiring employees to provide urine samples while supervised is invasive of their privacy and can negatively impact employee trust
  • Drug tests may not be reliable in all scenarios. The duration after use that a drug remains detectable varies widely depending on the person, type of sample and the drug
  • Drug tests can be expensive and invasive

In safety critical work sites where random drug testing has legal grounds to be used, it may still be limited in managing impairment.

Impairment reduces someone’s ability to make decisions or do their job and can be from: tiredness, stress, dealing with grief or a breakup, medications or alcohol and drug use. Knowing if someone used drugs does not mean they were affected by them at work.

Reducing impairment in the workplace, rather than any drug use, should be the focus. This can only be done through good management, a culture of reporting health and safety risks, and a system that encourages people to speak up if they notice an issue or someone else who is impaired.