Hair Follicle Test Results Levels Chart: Drug testing is an essential practice in many industries, from workplace compliance to medical evaluations and legal requirements. Among the various testing methods available—such as urine, saliva, and blood—hair follicle testing is considered one of the most reliable and long-term detection techniques. This method is widely used because it can detect drug use over a 90-day window, which is much longer than most other tests.
Understanding how a hair follicle test results levels chart works is crucial for both individuals being tested and organizations that rely on these results for decision-making. This article will provide a comprehensive overview of hair follicle testing, what the levels chart means, how results are interpreted, and common questions people often ask.
What is a Hair Follicle Drug Test?
A hair follicle drug test is a screening method that analyzes hair strands to detect the presence of drugs and their metabolites. Unlike urine or saliva tests, which typically detect recent drug use (a few days), hair follicle tests can reveal usage patterns over the past 90 days.
Why Hair?
When drugs enter the bloodstream, they circulate through the body and eventually reach the hair follicles. Small amounts of drug metabolites become embedded in the growing hair shaft. Since hair grows slowly (around 1 cm per month), each segment of hair can serve as a timeline of drug use.
How Hair Follicle Testing Works
- Sample Collection: A small amount of hair (usually 90–120 strands) is cut close to the scalp. Typically, 1.5 inches of hair are taken, which represents approximately 90 days of history.
- Laboratory Analysis: The sample is washed to remove external contaminants and then tested using advanced techniques such as ELISA (Enzyme-Linked Immunosorbent Assay) followed by GC/MS (Gas Chromatography/Mass Spectrometry) for confirmation.
- Result Reporting: Results are reported in nanograms per milligram (ng/mg) of hair. A levels chart is then used to compare results against cutoff thresholds to determine whether the test is positive or negative.
Hair Follicle Test Results Levels Chart
Here’s a simplified version of the commonly used cutoff levels for hair drug testing. Actual cutoff values may vary slightly depending on the laboratory and test type, but the general standards remain consistent.
| Drug Tested | Initial Screen Cutoff (ng/mg) | Confirmatory Test Cutoff (ng/mg) | Detection Window |
|---|---|---|---|
| Cocaine | 300 | 150 | Up to 90 days |
| Opiates (Heroin, Codeine, Morphine) | 300 | 200 | Up to 90 days |
| Amphetamines (Meth, MDMA, Ecstasy) | 500 | 250 | Up to 90 days |
| Marijuana (THC) | 1.0 pg/mg (picogram per mg) | 0.1 pg/mg | Up to 90 days |
| PCP (Phencyclidine) | 300 | 200 | Up to 90 days |
| Benzodiazepines | 200 | 150 | Up to 90 days |
| Barbiturates | 300 | 200 | Up to 90 days |
Key Notes on the Chart:
- Initial Screen Cutoff: This is the threshold level for the first test (ELISA). If the drug concentration is below this value, the result is negative.
- Confirmatory Test Cutoff: If the initial screen is positive, a more specific test (GC/MS) is done at a lower cutoff to confirm accuracy.
- Detection Window: Most drugs can be detected for up to 90 days, depending on hair length and growth rate.
How to Read the Hair Follicle Test Results Levels Chart
Let’s say a hair test reports the following:
- Cocaine: 220 ng/mg
- Amphetamines: 300 ng/mg
- THC: 0.8 pg/mg
Based on the chart:
- The cocaine result (220 ng/mg) is below the confirmatory cutoff of 150 ng/mg, so it is considered negative.
- The amphetamines result (300 ng/mg) is above the cutoff (250 ng/mg), so it is positive.
- The THC result (0.8 pg/mg) is below 1.0 pg/mg, so it is negative.
This means the person would test positive for amphetamines only.
Factors That Influence Hair Follicle Test Results
- Hair Type and Color
Dark and coarse hair tends to retain more drug metabolites compared to light or fine hair. This is due to higher melanin content binding more strongly with drugs. - Cosmetic Treatments
Bleaching, dyeing, or excessive washing may reduce drug levels, but rarely eliminate them completely. Labs often test for signs of tampering. - Drug Usage Pattern
Frequent and heavy drug use results in higher concentration levels, making it more likely to cross cutoff thresholds. - Length of Hair Sample
Standard testing uses 1.5 inches of hair, reflecting 90 days of history. Longer samples may extend the detection window. - Environmental Exposure
Labs wash samples to minimize false positives from external contamination (e.g., secondhand smoke).
Benefits of Hair Follicle Testing
- Long Detection Window: Detects drug use for up to 3 months.
- Difficult to Cheat: Unlike urine, hair tests are hard to manipulate.
- Non-Invasive: Collection is simple and painless.
- Reliable: Provides consistent and accurate results with low chances of false positives.
Limitations of Hair Follicle Testing
- Costly: More expensive than urine or saliva tests.
- Limited for Recent Use: Drugs used in the last 7 days may not appear because it takes time for hair to grow.
- Doesn’t Show Impairment: Indicates past usage but not whether the person is currently impaired.
Frequently Asked Questions (FAQ)
1. How far back does a hair follicle test go?
A standard test using 1.5 inches of hair detects up to 90 days of drug use. Longer samples can extend this window.
2. Can secondhand smoke cause a positive hair follicle test?
Unlikely. Labs wash hair samples to remove external contaminants. Positive results typically require repeated and direct drug exposure.
3. How soon after drug use will it show up in hair?
It usually takes 7–10 days for drug metabolites to appear in hair since the substance must grow out from the follicle.
4. Can bleaching or dyeing hair help pass a test?
Hair treatments may lower metabolite levels but rarely eliminate them. Labs are trained to detect tampering attempts.
5. Are hair follicle tests more accurate than urine tests?
Yes. Hair follicle tests are harder to cheat and detect drug use over a much longer period. However, urine tests are better at detecting very recent use (1–3 days).
6. What happens if my test is positive?
A positive result means drug metabolites were found above the cutoff levels. Depending on the situation, this may affect employment, legal cases, or medical treatment.
7. Do prescription drugs show up in a hair test?
Yes. If you take prescription medication, you should inform the testing authority beforehand to prevent confusion with illicit drug use.
8. How accurate are hair follicle test results levels charts?
They are highly accurate when performed in certified labs. The combination of initial screening and confirmatory testing reduces the chances of false positives.
Final Thoughts
The hair follicle test results levels chart plays a vital role in interpreting drug test outcomes. By comparing laboratory results against cutoff levels, it becomes clear whether drug use is present and at what concentrations. For employers, legal authorities, and individuals, understanding this chart is essential to making informed decisions.
While hair follicle testing is highly reliable, it’s important to remember that it reflects long-term patterns of drug use rather than immediate impairment. As such, it is often used in pre-employment checks, court cases, and monitoring programs where long-term habits are more relevant than short-term behavior.