There are various cut off levels for different drugs.  The cutoff levels are the concentration of drug metabolites discovered during the hair test.  For example, the cutoff level for amphetamines in the hair is 500 picograms per milligram.  For cocaine it is also 500 picograms per milligram.  For opiates the cutoff level would be 300 picograms per milligram. PCP is also 300 picograms per milligram. Marijuana (THC) is 1 picogram per milligram.

There is a chain of custody documentation when it comes to a hair test.  This means that your employer can not just cut your hair and test it themselves.  An independent lab will take the sample from any person required to take the hair test.  This chain of custody also means that the person providing the hair sample can not just walk in to the testing facility with the hair sample already removed from their body.  Who knows, they could have taken the sample from their child or even the family dog.  This is why the chain of custody is so important as to weed out any contamination or substitutions.

It generally takes anywhere from two to four days to obtain the results of your hair test.  The initial test is a radioimmunoassay test and if results are negative then they are usually available within three days.  If the results are positive after the initial test then a secondary examination is performed.  This secondary test is a confirmatory test through a gas chromatography/mass spectrometry test to provide a conclusive result and to assure that the sample was not a false positive for another substance whose characteristics are similar to illegal drugs.

(To Be Continued)