Hair Analysis in Forensic Toxicology: An Updated Review with a Special Focus on Pitfalls

The detection of drugs in hair analysis has progressively emerged as a consequence of the enhanced sensitivity of analytical techniques used in forensic toxicology; a greater advantage in using this matrix with respect to classical ones (i.e. urine and blood) is an easier and non-invasive sample collection, even when the careful supervision of law enforcement officers is required to avoid the risk that the sample may be adulterated or replaced. Moreover, according to the length of the hair, the history of drug exposure can be retrospectively monitored from few weeks up to months or years since sample collection.

Through a detailed revision of the existent literature, this manuscript provides information on the proper sample collection, preparation and analysis, as well as pitfalls in forensic hair analysis, and summarizes the wide range of application of this technology, including excessive alcohol drinking, doping, child abuse, and offences linked to drug use.

Verification of history of psychotropic drugs, alcohol and doping agents use by hair analysis, hair testing for driving license regranting and drug facilitated crimes, and testing for drugs in hair of children have been reviewed together with recent trends in hair contamination and possibility to disclose use of new psychoactive substances by hair analysis.

Hair analysis in forensic toxicology has been quickly emerged and improved in recent years; a deeper knowledge of advantages and limitations of this unique matrix is necessary for a better use in forensic caseworks.