Based on the episode: “Mycotoxins Are Not VOCs – Debunking Mold Misinformation”
In the mold world, one myth refuses to die: “Mycotoxins are VOCs. They off-gas into the air, you breathe them in, that’s how you get sick.” It sounds scientific. It uses all the right buzzwords: toxin, volatile organic compound, off-gassing. There’s just one problem: Mycotoxins are not VOCs. They do not off-gas. They are not airborne gases.
Mixing up the two isn’t just a technical error, it affects how people test, diagnose, and spend money trying to “detox” from something that isn’t behaving the way they think it is.
This article will walk you through:
- What VOCs actually are
- What mycotoxins actually are
- How the confusion started (hint: MVOCs)
- Why the distinction matters for your health, testing, and wallet
- What is the real route of mycotoxin exposure in buildings
What Is a VOC?
VOC stands for Volatile Organic Compound.
- Volatile = it evaporates easily into the air
- Organic = carbon-based
- Compound = a chemical substance
VOCs are gases or vapors you can breathe in. Examples are solvents from paints and finishes, off-gassing from new carpet or furniture, Alcohols, aldehydes, and ketones. In mold-related contexts, you’ll often see MVOCs (Microbial Volatile Organic Compounds.) These are VOCs produced by microbes such as bacteria and fungi (mold). MVOCs are small, light molecules, gaseous at room temperature, responsible for that musty, moldy odor. If you smell that “moldy” smell, you’re smelling MVOCs, not mycotoxins.
What Are Mycotoxins?
In classic professional references on bioaerosols and fungal toxins, mycotoxins are explicitly described as non-volatile. They don’t “off-gas.” They don’t migrate through walls or floors independent of particles.
Break the word down:
- Myco = mold or fungus
- Toxin = a poisonous substance
At its simplest, a mycotoxin = a mold toxin. Mycotoxins are secondary metabolic products of fungi. They are relatively large, non-volatile molecules. They are found in mold spores, the hyphae and mycelium (the root-like structures), and the substrate the mold is growing on (drywall, wood, grains, etc.)
Two key points:
- Mycotoxins are solids, not gases. Mycotoxins do not evaporate into the air like VOCs.
- Mycotoxins are attached to particles. If you inhale, ingest, or get exposed to mycotoxins, you were exposed to dust, spores, fragments, or contaminated material, not some toxic gas floating across the house by itself.
How the Myth “Mycotoxins Are VOCs” Originated
The confusion likely comes from how these terms appear together in technical texts and training materials. You might see a passage that says mold can produce secondary metabolic products such as mycotoxins, antibiotics, and VOCs. You might see sections discussing mycotoxins in the same chapter as MVOCs (microbial VOCs). With both terms near each other, such that for someone who is not trained in mycology or building science, it’s easy for their brain to merge those concepts and conclude, “MVOCs must mean mycotoxin VOCs.”
But that’s wrong. This is correct:
- MVOC = Microbial Volatile Organic Compound (odor chemicals from microbes)
- Mycotoxin = mold toxin (solid, non-volatile, attached to particles)
They are not the same.They’re not the same class of molecule. Then add AI and internet summaries that repeat whatever is most common, not necessarily what’s most accurate, and disinformation spreads.
How Mycotoxins Reach People
Because mycotoxins are non-volatile solids, you don’t get exposed to them by breathing some invisible gas that seeped out of your wall. You get exposed when particles move. Mycotoxins can be present on spores, fragmented hyphae and mycelium, contaminated dust and debris, pieces of moldy drywall, wood, carpet, and so forth. Exposure routes include:
- Inhalation of spores or dust
- Ingestion (for workers or homeowners who get contaminated dust on their hands, then touch their mouth, food)
- Skin contact, especially during remediation when proper PPE isn’t used
One of the biggest risks for remediation workers (who often focus only on respirators) is ingestion: handling contaminated materials all day, then touching their face, food, or water without thinking. If you’re imagining mycotoxins as some kind of vapor cloud leaking through walls, stop. That’s not what’s happening.
What’s That Musty Smell?
If mycotoxins don’t off-gas, why do moldy buildings smell so bad? That smell is from MVOCs (microbial VOCs), not mycotoxins. MVOCs are small, volatile chemicals produced during microbial metabolism. They may include alcohols, aldehydes, ketones, and other low molecular weight compounds. They are responsible for “musty basement” odors, “Mildew” smells, and spoiled-food odors. The Key distinction:
- MVOCs = gas-phase odors
- Mycotoxins = solid-phase toxins on particles
You could have strong mold odor (high MVOCs) and no measurable mycotoxins, or mycotoxins present on dust and spores, even with little or no noticeable odor. Smell is a clue that something is growing; it’s not a test for mycotoxins.
Why This Matters in Real Life
You might be thinking, Okay, fine, chemistry lesson. Why is this important for me as a homeowner, patient, or practitioner?” Because this misunderstanding leads to:
1. Misdiagnosis and incorrect assumptions
If you think mycotoxins are VOCs, you might assume, if I can’t smell it, it must not be there; If I run an air VOC scan and don’t find mycotoxins, the building is safe; If we “seal the wall” but don’t remove the mold, we’re blocking off the toxin gas. All of that is wrong.Mycotoxins don’t off-gas, therefore VOC testing isn’t a tool for measuring them. Sealing mold behind coatings doesn’t magically neutralize its toxins, especially if particles can still escape when the material is disturbed or deteriorates.
2. Misuse of testing and money
Believing mycotoxins are VOCs can drive people toward expensive testing panels that don’t actually answer the question they think they’re asking, “off-gassing” analyses that are not designed for mycotoxin solids, and unnecessary or misinterpreted air testing.
Instead of asking, “Are there toxic gases leaking from the wall,” the more useful questions are:
- Is there mold growth? Where?
- Are spores and fragments being released into the air or dust?
- What’s the source of moisture? How do we stop it?
3. Wasted energy on the wrong problem
Focusing on “toxic mycotoxin gas” distracts from the real priorities: identifying actual mold growth, fixing moisture problems, removing contaminated materials properly, and controlling dust and particle exposure. You don’t need to chase phantom gases; You need to find the mold and deal with it.
For Homeowners and Patients: What to Focus On
If you’re worried about mold and mycotoxins, here’s a more grounded approach:
- Stop thinking “off-gassing.” Start thinking “particles.” Dust, spores, fragments, contaminated materials - that’s your exposure pathway.
- Get a real inspection with real “tests.” Do a visual investigation, moisture mapping, and most important, Wall cavity check to look for actual mold growth, not just numbers on a lab report.
- Fix water problems. Roof leaks, plumbing leaks, window failures, and condensation issues are the root causes of mold growth.
- Remove moldy materials; Don’t treat or seal them. Mycotoxins and spores are in and on the material.. You can’t seal that risk away and pretend it’s gone.
For Practitioners and Inspectors: How to Communicate This Clearly
If you’re a clinician or inspector, you can help your clients by being precise. Say, “mycotoxins are non-volatile solids attached to particles,” not “mycotoxin fumes.”Explain that MVOCs (microbial VOCs) are what create odors and that they are not the same as mycotoxins. Emphasize that testing for mycotoxins (in urine, dust, etc.) is not the same as testing for VOCs, and each has limitations. Keep the conversation centered on source (mold) removal and particle exposure reduction. That’s how you help people think clearly and avoid wasting time and money on misunderstandings.
Key Takeaways
- Mycotoxins are not VOCs. They are non-volatile metabolites attached to particles that include spores, fragments of mold, and contaminated materials mold is growing on.
- MVOCs (microbial VOCs) are gases that create musty mold odors. They are chemically different and behave differently from mycotoxins.
- There is no such thing as “mycotoxin off-gassing” from walls or materials. Exposure happens through particles, not gases. Focusing on the “toxic gas” idea leads to misdiagnosis, misguided testing, and inadequate and improper remediation strategies.
- The real priorities are: Find actual mold growth. And remove contaminated materials. Fix moisture problems. Reduce dust and particle exposure
Don’t chase invisible “mycotoxin fumes.” Find the mold, fix the water, and remove the contaminated materials.
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Disclaimer
The post is designed for educational purposes only. Our goal is to provide information and scientific data as to the potential hazards in the home or office. All the factors to be considered are beyond the scope of this post. We do not assume responsibility for choices or decisions made including those regarding mitigation. The principles presented here should empower the reader to make informed choices. Book a consultation.