What is fingernail drug testing?

Q:

What is fingernail drug testing?

A:

Fingernail drug testing can be used as an alternative to hair follicle drug testing orurine testing. Nails are made up of a material called keratin, which hair is also made from. Over time, substances like drugs move out of the blood stream, and they can become stuck in the keratin fibers. This is why fingernail testing can be used to detect a history of drug or alcohol abuse.

Testing method and window of detection

Fingernail testing has the ability to identify historical drug use from as early as 1-2 weeks after exposure, and as long as one year after exposure. The timeframe for detecting a history of drug abuse through nail testing will depend on factors such as dose, which substances have been used, and on individual variations. One-time drug use does not guarantee that the substance will be detected through a fingernail drug test.

A minimum of 2-3 mm of clippings are taken from each fingernail to provide sufficient weight for a sample. Toenail clippings can also be used. Fingernail clippings can show evidence of drug use history up to six or eight months later. Toenails can be used up to a year after drug or alcohol abuse.

It is important to recognize that secondary exposure to drugs can show up immediately in nail tests. If a person handles drugs or is around someone who is smoking drugs, the substance can work its way through the pores and bind to the keratin. This could have the potential to yield a positive result when tested.

When to choose fingernail testing

Urine tests for certain drugs may only be able to be used up to a few days after substance abuse but nail testing could detect illicit drug use from much further back. Therefore, due to it's later window of detection, fingernail testing can be used when a more historical picture of drug use is required.

Fingernail drug testing may also be chosen when a hair test is not suitable. The person being tested might have:

  • No hair, or an insufficient amount of hair required for the sample
  • Chemically treated hair
  • Concerns about their appearance after a hair sample is taken

Overall, fingernail drug testing can be used as a reliable alternative to hair testing.

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Written by John Hawes
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John Hawes is the CCO and co-founder at SureHire Occupational Health Testing. John graduated in 2001 from the University of Alberta with a Bachelor of Science degree in physical therapy. As a former physical therapist, John uses his knowledge of physical therapy and interest in ergonomics and biomechanics to devise fit for work testing.

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