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.
8 citations,
October 2014 in “Journal of analytical toxicology.” Chemical hair straightening significantly reduces detectable drug levels in hair.
33 citations,
June 1995 in “International journal of legal medicine” Environmental factors can greatly reduce drug levels in hair.
14 citations,
January 1996 in “Journal of Forensic Sciences” Hair can absorb and transfer opiates when soaked in water, with damaged hair absorbing more.
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.