TLDR Cannabinoids like THC and THCA get into hair through skin oils, not hair color.
The dissertation investigated the mechanism of cannabinoid incorporation into hair, specifically focusing on delta-9-tetrahydrocannabinol (THC) and 11-nor-delta-9-tetrahydrocannabinol (THCA). It was hypothesized that these cannabinoids incorporate into hair independently of melanin binding, unlike some basic drugs. Experiments with pigmented and nonpigmented hair from Long-Evans rats showed no significant difference in THC and THCA incorporation, supporting the hypothesis. Further studies using cultured melanocytes indicated that factors other than pigmentation affect cannabinoid retention. THC was found to localize with epidermal keratins and sebaceous glands after multiple administrations, suggesting incorporation via sebum and skin rather than direct melanin interaction.
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February 2002 in “International Journal of Cosmetic Science” Recent findings show that hair growth and color are controlled by a complex network of signals in the hair follicle.
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Forensic hair analysis for drugs is now more reliable and accurate.
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