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Uni hair analysis does not prove any use of cannabis
So far, it was considered certain that at least the detection of specific degradation products of the main cannabis active ingredient THC in the hair a consumption prove beyond any doubt. Researcher at the Institute for Legal Medicine of the University Hospital Freiburg around the toxicologist Prof. Dr. med. Volker Auwärter showed now by experimental work that this conclusion is not allowed. The results of the work have been published in the renowned journal Scientific Reports of the Nature Publishing Group.
Cannabis consumption can not be clearly demonstrated by hair analysis. Image: Monkey Business - fotolia The Freiburg study has now shown that THC storage, which is measured inter alia for abstinence checks in the context of driving fitness tests in the hair, does not take place via the bloodstream when taking THC. Also, a breakdown product of THC, which has been used in cases of doubt so far for the clear evidence of consumption, can be transferred via sweat and sebum of a consumer to other persons. To provide experimental evidence, two of the authors conducted a one-month self-experiment with regular dronabinol (semi-synthetic THC) and extensive measurements.
"The new findings are particularly important in the analysis of child hair samples in the context of custody issues, as cannabinoid transmission in close body contact is particularly likely and can lead to completely wrong conclusions," says Prof. Auwärter. In countries where drug screening is carried out on workers or applicants, the result of a misinterpretation of the results of a hair analysis could lead to job losses or exclusion from the application process, the expert said.
The researchers from Freiburg have already been able to prove in earlier studies that THC contamination of the hair by cannabis smoke caused by outside persons can come from other people, which is preserved even after numerous washes. In addition, mere manipulation with cannabis transfers relevant quantities of cannabinoids to the hair. (Title of the original article: Finding cannabinoids in hair does not prove cannabis consumption)