Legal and Ethical Issues Concerning Workplace Drug Testing

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Types and Reliability

There are a number of common ones - I'll talk about urine, sweat, hair and blood testing. By far the urine tests are the most common and less invasive (also painless). Urine is the result of the body's filtering of waste products and byproducts from metabolism of many things which enter our body - including drugs. Most drugs are metabolized in the body into other, usually harmless, byproducts which are then filtered out of the bloodstream via the kidneys and enter into the urine. These byproducts don't normally exist from the metabolism of anything else in the body, so the presence of such byproducts in the urine is indicative of previous drug consumption.

That said, not all drugs have metabolites which are released into the urine. Urine is also filled with other metabolites, which means that unless a lab can isolate the specific metabolite from a drug, there might be interference from other metabolites. Urine can also be dilute of metabolites if the kidneys filter out a lot of water from the blood. This might be important as some metabolites may only be traceable if there is an adequate concentration in the urine.

Thus, for urine, reliability depends, to a degree, on concentration and specificity of tests to the metabolites being traced. Most urine tests are specific and work at low concentrations however, which leads to urine testing as one of the most common methods of drug testing. As metabolites are filtered out, there is a period of time during which urine testing is effective because not all the metabolites have been filtered out. For many drugs, this is often a matter of 24 hours to one month, depending on the drug. A large range of drugs fall within the 2-3 days range, within which metabolites can be accurately detected. Compare this to say, blood testing, where most metabolites can only be accurately detected for 2-5 days for most drugs.

Blood testing; however, trumps urine testing when it comes to detecting the presence of the drug compound itself and its metabolites at lower concentrations than required for urine testing. It is also less hindered by other byproducts, although it has a host of other substances that need to be filtered out that urine doesn't have. The reliability in blood testing is high in the sense that specificity and sensitivity (to concentration) can be much higher when compared to urine testing.

Another common type is saliva testing. Easy to administer (even more so ...