53 citations,
November 1997 in “Journal of Forensic Sciences” Darker hair in guinea pigs holds more codeine than lighter hair.
63 citations,
August 1996 in “Forensic Science International” Cosmetic treatments like bleaching and perming can greatly reduce opiate levels in hair, possibly leading to false-negative drug tests.
14 citations,
January 1996 in “Journal of Forensic Sciences” Hair can absorb and transfer opiates when soaked in water, with damaged hair absorbing more.
48 citations,
July 1996 in “Human & Experimental Toxicology” Human enzymes can detoxify harmful substances but might also increase their cancer risk.
1 citations,
August 2006 in “International forensic science and investigation series” Hair testing is a reliable method for detecting workplace drug use when done with proper sample preparation and confirmation.