Adulterated Specimen
A urine specimen that contains a substance not expected in human urine — or an expected substance at an abnormal concentration — indicating tampering.
Key Facts
- A specimen containing a substance not normally found in human urine, or at an abnormal concentration
- Detected during specimen validity testing at the laboratory
- A verified adulterated result on a DOT test is treated as a refusal to test
- Common adulterants include oxidizers, nitrites, and pH-altering chemicals
An adulterated specimen is one to which the donor has added a foreign substance (such as an oxidizing agent, nitrite, or acid/base) in an attempt to mask drug use or interfere with laboratory analysis. Laboratories identify adulteration through specimen validity testing, which checks pH, creatinine, specific gravity, and the presence of oxidants. Under 49 CFR Part 40, when the MRO verifies a specimen as adulterated, the result is reported to the employer as a refusal to test — the same consequence as a verified positive. The donor may request that the split specimen be tested to challenge the finding.
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Frequently Asked Questions
- What happens if a drug test specimen is adulterated?
- For DOT-regulated testing, a verified adulterated specimen is reported as a refusal to test, which carries the same consequences as a verified positive: immediate removal from safety-sensitive duty and referral to a Substance Abuse Professional (SAP) before return-to-duty is possible. For non-DOT programs, consequences follow the employer’s written policy, but most treat adulteration as an automatic failure.
- How do labs detect an adulterated specimen?
- Certified laboratories run specimen validity testing on every specimen: pH (acceptable range roughly 4.5–9), creatinine and specific gravity (to detect dilution or substitution), and oxidant screens that detect bleach, nitrites, chromium, and commercial adulterant products. Results outside acceptable ranges are confirmed with a second, more specific test before the specimen is reported adulterated.
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50
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