Hair Drug Testing: New Approach Differentiates Deliberate Ingestion or Introduction From Environmental Exposure
by Jo Ellen Nott
Drug testing is a commonly accepted form of compliance control used widely in the U.S. It is used in criminal investigations, child welfare checks, and probation or parole monitoring. Drug tests are often required while applying for employment or to retain employment. The results need to be accurate to shield individuals from loss, liability, or prosecution.
Compared to other biological samples, hair provides a longer window for drug detection. Drugs are deposited in hair through blood circulation by various mechanisms. After being deposited in the hair, the drug remains stable and can be detected after a longer period—up to 12 months depending on the length of the hair—when compared with other biological samples such as saliva, blood, and urine. Drug detection in bodily fluids is possible only for days, not weeks or months.
Standardizing drug testing on hair samples has been a challenge due to difficulties in distinguishing between deliberate drug use and passive environmental contamination. Much like second-hand smoke, drugs can be deposited on hair without the individual having ingested them. Traditional methods rely on washing the hair to remove surface contaminants, but this process can be inconsistent and may even trap drugs within the hair shaft.
Researchers Dr. Megan Grabenauer and Katherine Bollinger of RTI International tested a new approach to hair analysis with a grant from the National Institute of Justice. Their hypothesis was to analyze conjugated phase II metabolites present in hair samples. These metabolites are byproducts of the body’s natural drug breakdown process and would not be present if drugs came into contact with hair from environmental exposure.
The two researchers conducted experiments to determine whether (1) these metabolites are present in detectable amounts in hair, (2) analyzing them could replace current decontamination procedures (washing the hair samples before testing), and (3) they are unintentionally produced during analysis. They found that phase II metabolites are measurable in hair from known drug users and that they could extract opioids, cocaine, and amphetamines from hair without creating metabolites unintentionally.
The limitations of their study were a small sample size and limited availability of reference standards. However, their results are promising and point to metabolite analysis as a superior drug testing method. Experts predict it can lead to updated policies and procedures for hair drug testing while reducing concerns about second-hand contamination and misinterpretations.
Sources: Egyptian Journal of Forensic Science, Journal of Analytical Toxicolgy, Forensic
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