You breathe, you commute, you sit near a smoker at a backyard party — and your body quietly logs the experience. The N-Acetyl (2-Cyanoethyl) Cysteine (NACE) test is one of those quiet logs. It captures a fingerprint of acrylonitrile exposure, a volatile chemical found most prominently in tobacco smoke and certain industrial settings. Think of it as a short-term exposure diary written in your urine. Want to see what your environment is really doing to you?
What This Test Actually Measures
Plain-English definition
The NACE test detects N-acetyl-S-(2-cyanoethyl)-L-cysteine in urine, a “mercapturic acid” your body makes after processing acrylonitrile. In plain terms: acrylonitrile gets in, your liver binds it to glutathione, and the end-product — NACE — shows up in urine. Higher values generally mean more recent exposure. Ready to decode what your daily air might be adding up to?
How it gets into the body
Acrylonitrile mainly enters through inhalation. It’s a component of cigarette smoke and can be present in certain industrial emissions, polymer manufacturing, and combustion byproducts in urban air. Once inside, it’s metabolized and conjugated, with some acrylonitrile forming adducts and a portion cleared as NACE. Because the lungs are the primary entry route and the liver handles the detox steps, the timing of exposure and your metabolic capacity both matter. Curious how a single smoky room can change tomorrow’s number?
What sample you’ll provide
This is a urine test. Most labs use a spot urine sample and correct the result to creatinine to account for dilution. The window captured is short — roughly the prior day or two — so the value reflects recent exposure rather than your lifetime history. If you’re after the last 48 hours in high resolution, this is your lens. Want to see how fast your number shifts after changing your routine?
How the Test Works
Collection and timing
You provide a standard urine sample, often a midstream collection. Consistency helps with comparisons, so many programs aim for a similar time-of-day on repeat tests and note recent activities such as travel, workplace shifts, or time spent near smoke. Because hydration dilutes concentration, creatinine correction or specific gravity helps stabilize the interpretation across samples. Ever compare two photos with different lighting and wish you’d used the same filter?
Laboratories typically measure NACE by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This method isolates the compound and detects it with high specificity at very low concentrations. Labs report values in ng/mL or μg/g creatinine, with method detection limits designed for environmental biomonitoring. It’s the kind of instrumentation used in population studies for chemicals in the air we breathe. Wondering how sensitive it is to a single evening around secondhand smoke?
What the number represents
Your result reflects the urinary concentration of NACE, the end-stage mercapturic acid of acrylonitrile metabolism. Because NACE turns over quickly, the number mirrors recent intake rather than cumulative exposure. It’s a snapshot, not a biography. If you removed a major source yesterday, you’ll often see movement soon. Want to use that short half-life to run a small personal experiment?
What the Results Mean
Reference intervals vs. personal context
Population ranges provide context, often drawn from large biomonitoring programs that include smokers and non-smokers. But interpretation shifts with your reality: tobacco exposure, workplace environment, urban air quality, kidney function, and timing since last exposure. Two people with the same number can have very different stories. The key is pattern plus context. Which story does your number fit?
Pattern recognition
NACE often rises in tandem with other smoke-related markers. When it travels alongside urinary cotinine (nicotine exposure) and other volatile organic compound metabolites — like 3-HPMA for acrolein or HMPMA for crotonaldehyde — the pattern points toward tobacco smoke as a common source. In an occupational setting, a high NACE with low tobacco markers may lean industrial. Patterns help separate “I sat around a campfire” from “my workplace air needs attention.” Which cluster does your data resemble?
Follow-up testing
Because NACE reflects recent exposure, repeat testing after source changes can be informative. If you reduce time near smoke or improve ventilation in an industrial zone and NACE drops on the next draw, you’ve got evidence that the fix is working. For a longer view of acrylonitrile exposure, some programs pair urinary NACE with hemoglobin adducts that integrate weeks to months. Is your exposure an isolated blip or a recurring theme?
Key Systems Affected
Nervous system
Acrylonitrile is a volatile nitrile that can affect the central nervous system at higher exposures. Headache, dizziness, and nonspecific neurological symptoms have been reported in occupational contexts. Mechanistically, reactive intermediates and downstream oxidative stress are the suspects. NACE itself is just a messenger, but its appearance suggests upstream contact with a neuroactive chemical. Could a rise in this marker help explain why certain environments leave you feeling off?
Liver and detox pathways
The liver does the heavy lifting. Acrylonitrile is metabolized and then conjugated to glutathione. Enzymes in the mercapturic acid pathway complete the handoff — trimming and N-acetylating the conjugate so it can exit in urine as NACE. High throughput through these pathways means more demand on glutathione and related enzymes. In people with concurrent oxidative stress, the same pathway may carry more strain. What might your liver be telling you through this small molecule?
Kidneys and filtration
NACE leaves via the kidneys. Hydration, urine flow, and kidney function all shape the measured concentration. That’s why creatinine correction or specific gravity is often used to normalize results. In reduced renal function, levels may not mirror exposure perfectly, because clearance dynamics shift. Could the kidneys be coloring how this exposure signal looks on paper?
Endocrine and metabolism
Acrylonitrile is not classically categorized as a potent endocrine disruptor, but volatile organic compounds can interact with metabolic pathways and redox signaling. In high-exposure settings, shifts in energy metabolism often reflect systemic stress, not a single hormone axis. NACE won’t diagnose a hormonal issue, yet it can flag an environmental input that nudges metabolic resilience. Is environment one of the levers moving your energy and recovery curve?
Common Sources of Exposure
Environmental and household
Tobacco smoke is the standout source. That includes active smoking and secondhand exposure in homes, cars, bars, or outdoor gatherings with dense smoke. Urban air near heavy traffic or industrial zones can contribute smaller amounts. Building materials and consumer plastics use acrylonitrile in manufacturing, though fully polymerized products in the home are not typical high emitters under normal conditions. Which rooms or routines might quietly add to your exposure?
Dietary and occupational
Diet is usually a minor contributor for this compound, though trace nitriles can form with high-heat cooking. The occupational picture is clearer: polymer and fiber plants, rubber and plastics manufacturing, certain adhesive or resin workflows, and facilities handling acrylonitrile monomer. Combustion-related jobs may also see intermittent exposure. If your NACE is high and you don’t smoke, is your workplace the missing piece?
Clues from history
Ask yourself: Have you spent time around smokers? Started a new role near polymer processing? Noticed headaches during specific shifts? Experienced a jump in traffic exposure or construction near home? Those clues help triangulate where acrylonitrile could be entering the picture. What changed in your world around the time your value rose?
Detoxification and Elimination
Physiology 101
Your body tags acrylonitrile for exit via a well-known route: glutathione conjugation followed by enzymatic trimming and N-acetylation, producing NACE for urinary excretion. The process is relatively quick. That speed is why NACE levels align closely with exposures over the prior 24–72 hours. In biomonitoring, fast turnover is a feature, not a bug. What could you learn by watching that short arc change?
Systems that support clearance
Glutathione availability, transferase activity, and transporter function move the process along. Normal bile flow and renal excretion finish the job. These aren’t abstract pathways — they’re everyday cellular routines that rise to the occasion when you meet a volatile nitrile. If clearance is the highway, NACE is the traffic counter. Is your highway moving at the speed you expect?
Why responses vary
Genetic variation in detox enzymes, differences in glutathione status, co-exposures that induce or inhibit metabolic enzymes, and underlying illness can all shift how fast NACE appears and clears. Kids, pregnant individuals, and people with kidney or liver impairment may show different patterns at the same environmental level. That’s why population charts are helpful but not definitive. Does your physiology process the same air differently than your neighbor’s?
Biomarker Correlations
Functional context from broader labs
A single exposure marker tells part of the story. Add liver enzymes (ALT, AST, GGT), inflammatory signals (hs-CRP), and oxidative stress indicators, and you can connect exposure to response. Urine specific gravity or creatinine adds a check on dilution. Cotinine, a nicotine metabolite, helps attribute the source when tobacco is in the mix. Is your body shrugging off the exposure or pushing back?
Nutrient cofactors and capacity
Glutathione depends on sulfur amino acids such as cysteine, and enzymes require micronutrient support to function well. While NACE doesn’t measure nutrient status, it rides the rails those nutrients maintain. Redox markers, homocysteine, and related methylation or transsulfuration signals can hint at capacity. Are the tracks sturdy enough for the traffic your environment sends?
Interpreting together
If NACE rises while cotinine and smoke-related VOC metabolites also rise, the narrative is consistent with recent tobacco smoke exposure. If NACE stays high despite low tobacco indicators, occupational or environmental sources merit a closer look. When liver and inflammatory markers remain steady, the exposure may be modest or well handled. Pair trendlines rather than chasing single spikes. What story emerges when you overlay these graphs?
Optimal vs. Normal
Population ranges
Reference values often come from large surveys that include both smokers and non-smokers. They show what’s common, not necessarily what’s ideal for you. Smoking status, age, and urban versus rural living can shift where the percentiles sit. Seeing yourself on that curve is helpful. Does your dot land where you expected?
Longevity-oriented targets
For chemicals tied to combustion and industrial air, many clinicians prefer the lowest feasible levels — within the constraints of modern life — rather than simply falling within a broad “normal.” That’s not alarmist, just pragmatic where carcinogenicity or chronic exposure concerns exist, though risk depends on dose and duration. It’s about direction and margin, not perfection. What small shifts would move you toward the lower side of your own baseline?
Trend over time
A single NACE value is a snapshot. A series is a story. Directionality, especially after a clear source change, often matters more than one number. Reproducible lows after practical mitigations suggest your environment and physiology are aligned. Are your trendlines telling you you’re heading the right way?
Why Testing Is Worth It
From mystery to measurement
Symptoms like headaches or brain fog can be maddeningly nonspecific. NACE translates a slice of the environment into data, giving you a handle on recent acrylonitrile exposure. When you can measure it, you can start to relate cause and effect with a little more confidence. Isn’t that the point of testing in the first place?
Guiding remediation
When NACE is elevated, the next questions get concrete: tobacco smoke, workplace air, urban hotspots. Measured changes after simple environmental adjustments often validate what works. Whether you track a smoke-free experiment or test after ventilation upgrades, the lab becomes your feedback loop. What’s the quickest lever you can test in your own life?
Prevention and baseline
Even if you feel fine, a baseline helps. Environmental exposures ebb and flow with seasons, moves, jobs, and habits. NACE offers a way to mark “your normal” and catch drift early. Prevention is easier when you spot the change while it’s still small. What would you learn from a baseline before your next big life shift?
How This Test Fits Into Real-World Interpretation
Environmental sources
Think exposure scenarios. A night in a smoky venue, daily secondhand smoke in a car, proximity to industrial stacks, or high-traffic commutes can each nudge NACE. E-cigarette aerosols have different profiles; while combustion is the major acrylonitrile source, some lab analyses have detected nitriles in certain vaping conditions, though findings vary and more research is needed. Mapping your routine to your result is the practical move. Which single environment would you test first?
Assay differences and limitations
Not all labs report the same units, detection limits, or correction methods. Creatinine-corrected values help with day-to-day dilution variance, but muscle mass, hydration, and kidney function can still influence interpretation. NACE is specific to acrylonitrile exposure, yet it doesn’t diagnose disease, quantify total toxic load, or pinpoint exact sources without context. It is one instrument in the orchestra. Which other instruments will you bring into the mix?
Response nonlinearity
At higher exposures, detox pathways may saturate, and co-exposures can induce or inhibit metabolic enzymes. That means a doubling of exposure won’t always produce a tidy doubling of NACE. Smoking cessation can produce rapid drops, while intermittent workplace hits may create sawtooth patterns. Knowing that biology isn’t strictly linear helps you read the curves with less confusion. Does your pattern look like a slope, a spike, or a staircase?
Superpower: Turning Exposure Data Into Direction
Environmental exposure is measurable and actionable when paired with how your body responds. NACE shows a recent acrylonitrile signal; broader biomarkers show whether that signal mattered to your physiology. Putting them side by side turns numbers into a narrative you can actually use.
Ready to see the full picture? Pair your NACE result with Superpower’s 100+ biomarker panel to connect exposure with liver stress, inflammation, redox balance, and recovery — and watch how your environment and biology move together in real time.
