Clinical applications of hair testing for drugs of abuse--the Canadian experience.
Level 4 - case-series / case-control
Descriptive case series and laboratory report without a control group.
PubMed 10689580 · doi:10.1016/s0379-0738(99)00171-1
What was done
The authors evaluated the clinical and forensic applications of hair analysis for identifying exposure to various illicit and medicinal substances, including trace metals, barbiturates, amphetamines, opiates, phencyclidine, cocaine, nicotine, and cannabis. Over 1,000 hair samples across diverse populations (newborns, children, adults) and contexts (criminal cases, athletes, child custody disputes) were tested using radioimmunoassay (RIA) for initial screening and gas chromatography-mass spectrometry (GC-MS) for confirmation.
What was found
The abstract reports no numerical diagnostic data or detection rates. It notes that the detection window for drug incorporation in hair is determined by hair length and typically ranges from one week to several months, providing a cumulative measure of long-term exposure.
Why it matters
Hair testing extends the biological window of drug detection compared to short-lived blood or urine markers, which is useful when self-reports are unreliable in clinical and legal settings.
Limits
The abstract reports no quantitative performance metrics, such as sensitivity, specificity, or false-positive rates. It does not account for potential confounders such as passive environmental contamination, cosmetic hair treatments, or racial differences in hair pigmentation.
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- supports Marijuana consumption from 6 months prior can be detected in human hair.