The Reliability of Hair Follicle Testing

Pre-employment drug testing and post-accident tests are becoming wide-spread procedures to prevent drug abuse in the workplace. Different types of analytical drug tests are used involving saliva, urine, blood, sweat and hair. Their reliability is important to prevent false positive results.

Advantages

• The chief advantages to hair follicle drug testing are that it's a non-invasive procedure, any body hair can be tested, hair is easy to store and ship and the testing can detect long term drug use in time periods going back three months or more. Chemical washing and bleaching do not affect the internal presence of drug traces in the hair.

Procedure

• After collecting a hair sample, it's tested by mass spectrometry or with a gas chromatography column to detect the presence of illegal parent drugs and their metabolites. These procedures detect ion ratios specific to the drugs and their byproducts.

Reliability

• As with many methods of drug testing, hair follicle tests may produce false positives by environmental contamination. It's not known exactly how the parent drugs and their metabolites get inside the hair. It may be by secretion of sweat, blood diffusion or entry from the environment. The drug test may be biased against certain minority or ethnic groups and people with particular hair types or colors.