Influence of Thermal Hair Straightening on Cannabis and Cocaine Content in Hair

This preliminary study demonstrated that thermal hair straightening significantly affected the concentrations of cannabis and cocaine in hair. In 17 cannabis-positive hair samples, THC levels decreased in 11 samples and increased in 6, while CBN levels increased in all samples after heat treatment. For cocaine, all 7 samples showed decreased cocaine and cocaethylene levels, but increased benzoylecgonine (BZE) levels. The study suggested that heat treatment at 200°C converts THC to CBN and cocaine to BZE, altering the drug content in hair. These findings indicated that thermal straightening should be considered when interpreting hair drug test results.