CANSFORD LABS

Under the microscope: 3 myths about hair drug and alcohol testing

May 26, 2016

3 myths about hair drug and alcohol testingThe science behind a drug test with hair and hair strand tests for alcohol can become quite tricky to follow, so it’s not surprising when people misunderstand certain facts or take particular actions based on mistaken beliefs. 

The problem with acting on mistaken beliefs is they can lead to negative consequences.

Here’s 3 myths about hair strand testing for alcohol and drugs to help clear up a few misunderstandings.

A visit to the Dentist will cause a positive cocaine test

At Cansford Laboratories, we get a surprising number of requests in a year to check that an individual has tested positive for cocaine because they had recently attended a dentist.  Presumably the thought is that lidocaine, sometimes used as a local anaesthetic in dental procedures is detected as cocaine. Be aware - this is not the case.  The LC/MS/MS instruments that we use identify the drugs and their metabolites very accurately, meaning we are able to detect the difference between lignocaine and cocaine.

Question about a hair test? Get in touch today to speak with an expert

Bleaching and other cosmetic hair treatments alter the results of a hair drug test

It's true that these treatments make the hair more leaky and lower the amount of drug retained by the hair. However, it’s very rare for all of a drug to be lost and the detection instruments we use are very sensitive so it’s very unlikely that drug use will be missed. Importantly, if it is, the hair will look and feel damaged, to the extent that the supervising social worker might well become suspicious that evasion of drug detection had been attempted.

For example, we tested a girl for use of methadone and she tested negative. The social worker was convinced that the girl had recently changed the colour of her hair recently and surprised her with unannounced hair test.  Enough new hair had grown though the scalp that was clearly black coloured and the subsequent test was very clearly positive for the drug methadone.

Detection of drug use has always got to bear in mind that there is the possibility that some drug users will try and subvert the test (whatever the test) if they can. The point is that care and attention to detail is required by everyone involved in the process.

People with blonde hair have a better chance of passing a hair test

There is no doubt that dark hair will take up more drug than blonde hair for the same level of drug use. Yet, a drug test with hair is set at a level of sensitivity that drug use by blonde-haired people is always detected. For the same level of use, the dark haired individual will have more drug in the hair and will look as if they are a heavier user than the blonde-haired user. However, that cannot be deduced from the hair drug levels by themselves.

We once tested a young couple who were following the same habit.  They used the same drugs at the same time and in the same doses. At the Court hearing the Court wanted to deduce from the hair levels that the dark haired boy was a “worse addict” than the blonde-haired girl.  This could not be deduced from the results.  All the results indicated was that the dark haired boy had taken up more drug in his hair than his girlfriend. As drug uptake into hair is dependent on the number of melanocytes in the hair (which give colour to hair) the explanation of the difference in results was attributable to biology not level of addiction. 

Overall, there are a few myths around hair drug testing that aren’t quite true and should be considered carefully by donors. Firstly, a visit to the dentist doesn’t mean a donor will test for positive for cocaine, as many labs use sensitive testing equipment that can tell the difference between lignocaine and cocaine. Moreover, bleaching hair doesn’t mean you can get away with covering up drug use – support staff i.e. social workers can help uncover the potential bleaching of hair. Finally, drug use by blonde-haired individuals can still be detected.

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