What it is, How it works

Hair testing is recognized as a potent method for identifying drug and alcohol consumption. It offers a long-term record by capturing biomarkers within the strands of growing hair. When taken from near the scalp, hair can offer a detection period of up to around three months for alcohol and drugs. The collection of hair is straightforward, relatively hard to tamper with, and simple to dispatch.

Collecting a 1.5-inch segment of roughly 200 hair strands (approximating the width of a #2 pencil) nearest to the scalp will yield 100mg of hair, which is the optimal amount for both screening and verification. For EtG, add-ons, and/or tests exceeding 10 panels, a specimen of 150mg is suggested. We advise utilizing a jeweler’s scale to weigh the specimen. If scalp hair is not present, an equivalent quantity of body hair may be gathered. "Head hair" specifically pertains to scalp hair. "Body hair" refers to all non-scalp hair types (such as facial and axillary hair).

Process Overview

The laboratory processing of a drug test consists of four key stages: Accessioning, Screening, Extraction, and Confirmation.

Accessioning entails the initial integration of a sample into a lab’s system, including verifying proper sealing and shipment, assigning a random LAN (Laboratory Accessioning Number), and completing any extra data input absent in an electronic chain-of-custody system.

Screening provides an initial rapid assessment for drugs of abuse. Though Screening is an economical method to negate drug use in most samples, a positive result requires confirmation to be valid in legal contexts. Any samples presumptively positive in Screening must undergo a secondary confirmation.

If a sample tests positive in the Screening phase, additional hair is extracted from the original specimen for the Extraction process. Here, drugs are extracted from hair in significantly lower concentrations compared to other methods (e.g., urine or oral fluid), making hair drug screening one of the most challenging methodologies.

Positive screening results undergo Confirmation through GC/MS, GC/MS/MS, or LC/MS/MS. All presumptive positive samples are cleansed before confirmation as necessary. The entire process from Accessioning through Confirmation undergoes review under the CAP (College of American Pathologists) Hair designation and ISO / IEC 17025 accreditation standards.

Advantages of hair drug testing:

Long detection window: Hair drug tests can identify drug use up to 90 days, unlike urine tests that have lesser detection duration.
Difficulty to cheat: It is quite challenging to deceive a hair drug test, ensuring more reliable results.
Provides historical data: It presents a usage pattern over time, beyond just recent consumption.

Limitations:

Cannot detect recent use: Drugs need 5-7 days to become traceable in hair.
Cost: Hair drug tests often incur higher costs compared to other test methods.
Variations in results: Elements such as hair color and individual hair growth differences can affect drug metabolite levels in the hair.

Note: Although commonly labeled as "hair follicle tests", the analysis is performed on the hair strand, not the follicle beneath the scalp.