It Is Possible for Your Hair to Test Positive in an Analysis without You Having Tried Marijuana

The analysis of hair to detect cannabinoids is often used in work tests in order to determine the behaviour of employees or when it comes to deciding custody over minors. However, in October, the magazine Scientific Reports published a new study carried out by the University of Freiburg in Germany that warns against the use of this type of testing.

After analysing old and new hairs with traces of different types of THC (the plant’s psychoactive component) researchers found three cannabinoids in people that had not consumed. According to the researchers, the hair testing that is carried out to determine if someone has smoked cannabis is inexact and it is very likely for someone to test positive for cannabis despite never having consumed it.

Cannabinoids can transfer over from regular consumers, through their hands, sweat or the smoke itself. In fact, many of them are not usually found in large quantities in the hair following consumption. On the contrary, there may be traces on the oldest parts of somebody’s hair, that is to say, on hairs that grew before consumption and should therefore not be affected by it.

The consequences of using these tests as evidence in legal cases can also cause serious and unfair consequences for people examined. Therefore, the professionals believe that there is an urgent need for other scientific assessments that support their study. At the moment, the most advisable thing would be to stop using these methods in decisive situations.