Workplace Drug Testing Explained!

We have seen in recent months in the media a number of articles reflecting the increasing number of companies in the UK utilizing drug testing as a tool for potential health and safety and performance issues to detect drug use by employees or job candidates. This is what workplace drug testing is all about.

Employers face a difficult task to choose the best sample to use in drug testing that suits best for their needs. The three common samples – urine, saliva and hair – each have different advantages depending on the purpose of the test and they can be complementary in different situations.

Drug testing in urine and saliva (or oral fluid) reflects drug use on a relatively short period before sample collection (24–72 h) depending on the drug, but it cannot detect impairment. Abstention from use for 3 days will often produce a negative urine test result.

Oral Fluid or Saliva is easy to collect. Drugs remain in oral fluid for a similar time as in blood and its use is a good way of detecting actual current drug use and is more likely to reflect impairment.  It is an ideal test in ‘post-accident’, for cause, and on duty situations.

Analysis of Hair provides a much longer window of detection, typically 1 to 3 months.  Hence the likelihood of a false negative test using hair is very much less than with a urine test.  Conversely, a negative hair test is a substantially stronger indicator of a non-drug user than a negative urine test. Hair analysis can indicate frequency of drug use.


Hair testing can detect 10 times more drug users than urine testing and it is a non-invasive technique.

It remains essential in all cases to combine drug testing with a clinical appraisal of the actual behaviour of the individual, before coming to any conclusion as to what action may be appropriate. The use of drug testing in the Workplace requires a clear, written policy that is discussed and agreed with all employees before testing starts.


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