Drug tests are crucial for various purposes such as criminal investigations, child welfare assessments, and probation or parole compliance. Hair drug tests, in particular, offer a more extended detection window compared to blood tests, as drugs remain in hair strands for months. While these tests cannot quantify drug usage, they can identify the presence of specific drugs. However, a significant challenge lies in determining whether the detected drugs are due to actual use or environmental contamination.

Experts in toxicology highlight the complexity of this issue. Drugs can enter hair through the bloodstream, sweat, or external contact. To address potential contamination, labs employ wash procedures to cleanse hair before analysis. Yet, these decontamination methods are not standardized, and washing may inadvertently incorporate drugs into the hair shaft.

Two toxicologists funded by the NIJ, Dr. Megan Grabenauer and Katherine Bollinger from RTI International, have suggested an innovative approach: focusing on drug metabolites—specifically conjugated phase II metabolites (drugs combined with an amino acid)—instead of the parent drug. These metabolites, which are processed by the body and generally non-toxic, should not be present in the hair of individuals merely exposed to drugs without using them.

The researchers aimed to answer three key questions:

1. Are the concentrations of these metabolites sufficient for measurement?
2. Can detecting phase II metabolites serve as an alternative to current decontamination procedures in hair drug testing?
3. Can these metabolites be unintentionally produced during sample analysis?

Ensuring Accurate Detection Methods

The researchers analysed samples from RTI’s hair inventory, including hair from known drug users, to determine if phase II metabolites were present. They also examined drug-free hair samples to ensure that their extraction methods did not inadvertently create these metabolites. Their findings included:

• Detecting measurable quantities of phase II metabolites.
• Developing two extraction methods for opioids, cocaine, and amphetamines.
• Confirming that their methods did not produce phase II metabolites accidentally.
• Using mass spectrometry to identify specific substances in hair (illustrated in Figure 1).
• Creating a reference list of potential drug use markers.

Advancing Drug Detection

The researchers optimized methods to standardize drug extraction from hair, ensuring that external contaminants resembling drug metabolites were not introduced during testing. This extends the detection timeframe and enables differentiation between actual drug use and environmental exposure. Accurate determination of drug use is particularly critical in judicial contexts.

While the research faced limitations due to the small number of hair samples from known drug users and the availability of phase II metabolites for reference standards, the findings are promising. The detection of conjugated metabolites in hair could significantly impact current hair drug testing policies and procedures, alleviating concerns about external contamination and interpretation issues.

Journal article

National Institute of Justice, “Detecting Drugs in Hair: Is It Drug Use or Environmental Contamination?,” June 4, 2024, nij.ojp.gov: 

https://nij.ojp.gov/topics/articles/detecting-drugs-hair-it-drug-use-or-environmental-contamination

Note this content has been edited