It is evidently known that drugs taken illicitly irrespective of the method of use does accumulate in the hair shaft. This could be by inhalation, snorting, injecting or orally. This accumulation can occur through the blood that nourishes the hair follicle, absorption through sweat and sebum as well as externally (e.g nicotine smoke). These compounds bind to melanin and also get incorporated in the keratinisation process within the hair shaft.
Research published in the International Journal in Experimental Medicine in 2015 shed some light by examining the hair shaft of illicit drug users by using an Electron Scanning microscope.
The hair shafts in cannabis users were not clearly defined and had node shaped large areas.
In cocaine users, the hair shafts were thin, ribbon like and damaged. The keratin structure was also disrupted.
In LSD users, the cuticle hair was destroyed. The shaft was fragile and broken.
In heroin users, the cuticle cells were partially broken and the hair shaft had debris.
It is known that drug use affects the skin and the hair being part of the structure was thought to be affected and this study demonstrated the different characteristics on the hair shaft caused by different illicit drugs. The hair shafts are weaker and prone to breaking.