Freiburg, Germany: THC metabolites may be present in the hair of individuals who have never ingested cannabis, according to clinical trial data published online in the journal Nature, Scientific Reports.
Investigators at University of Freiburg Medical Center in Germany assessed hair samples in human subjects with varying degrees of cannabis exposure. Researchers reported THC metabolites can be transferred from cannabis users to non-users via close body contact.
Authors concluded: "Our studies show that all three cannabinoids [THC, THC-A, and THC-COOH] can be present in hair of non-consuming individuals because of transfer through cannabis consumers, via their hands, their sebum/sweat, or cannabis smoke. This is of concern [in] child-custody cases as cannabinoid findings in a child's hair may be caused by close contact to cannabis consumers rather than by inhalation of side-stream smoke."