Method: LC-MS/MS (Liquid Chromatography/Tandem Mass Spectrometry) with creatinine normalization by Jaffe Reaction (CLIA 17D0919496); not cleared or approved by the FDA. Results reported in µg/g creatinine. Not a stand-alone diagnosis; should be interpreted in clinical context.
A derived biomarker is a value that is calculated from other directly measured biomarkers rather than being measured directly in the lab.
Key benefits of N-Acetyl Phenyl Cysteine (NAP) testing
- Benzene exposure tracking
- air pollution and tobacco smoke chemical burden assessment
What is N-Acetyl Phenyl Cysteine (NAP)?
NAP is a urinary mercapturic acid metabolite of benzene, a volatile organic compound found in tobacco smoke, vehicle exhaust, gasoline, and industrial environments. Measured via LC-MS/MS.
Why is N-Acetyl Phenyl Cysteine (NAP) important?
Benzene is classified as a known human carcinogen (per IARC Group 1 and EPA). Even low-level environmental exposure - from urban air, secondhand smoke, or gasoline fumes - contributes to cumulative personal exposure. Urinary NAP provides a direct biological measure of recent benzene exposure that air-quality estimates cannot match.
What insights will I get?
Your NAP level may indicate benzene exposure from urban air, tobacco smoke, gasoline, or industrial sources. Detectable levels in non-smokers may reflect urban air quality, commute routes, or occupational factors worth examining.





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