Mycotoxins: What Is Established, What Is Contested, and What Testing Can Tell You

Mycotoxins exist, they are well studied, and almost everything written about them online is about the wrong exposure route.

Related from GPMI: Mold testing, independent and lab-based.

This page separates the science that is settled from the claims that are not. We inspect and test only. We do not treat anyone, we do not sell remediation, and we have no supplement, protocol or cleanup to move, which is why we can afford to tell you where the evidence stops.

What mycotoxins are

Mycotoxins are toxic compounds produced by certain molds as secondary metabolites. They are not the mold itself and they are not mold spores. They are chemicals some fungi make, mostly when stressed or competing.

Several hundred are known. The ones that matter in practice are a short list:

• Aflatoxins, produced by Aspergillus flavus and Aspergillus parasiticus. The most studied of all, and a recognized human carcinogen at dietary doses.
• Ochratoxin A, produced by Aspergillus and Penicillium species, associated with kidney toxicity.
• Trichothecenes, including the ones produced by Stachybotrys chartarum, the species behind the black mold reputation.
• Fumonisins and zearalenone, Fusarium mycotoxins and mainly agricultural concerns in cereal crops.
• Patulin, associated with apple juice, and ergot alkaloids, historically associated with contaminated flour.

Where the evidence is strong

Mycotoxins in food

This is where mycotoxin science lives. Contaminated food, tree nuts, dried fruits, coffee and animal feed are a documented and regulated food safety issue. The Food and Drug Administration sets action levels for aflatoxin in human foods, and the World Health Organization treats dietary exposure to mycotoxins as a major concern in parts of the world where grain storage is poor.

Aflatoxin’s link to liver cancer at dietary doses is one of the better established findings in toxicology. Mycotoxin contamination of the food chain, and efforts to prevent mycotoxin contamination in food processing, are the subject of most of the literature you will find.

Animal health and animal feed

Farm animals eating contaminated feed are affected across many animal species, and the feed industry monitors for it continuously. Much of what is known about adverse health effects comes from animal studies rather than from people.

Occupational exposure

Agricultural workers handling moldy grain, silage or compost can inhale very high concentrations of spores. Organic dust toxic syndrome and hypersensitivity pneumonitis are documented outcomes in that setting.

Note what all 3 have in common: the dose is enormous compared with a damp bathroom.

Where the evidence is contested

Household indoor exposure

The claim that mycotoxins from mold growth in an ordinary home cause a distinct systemic human disease is not established. It is asserted confidently across the internet, usually by people selling testing, supplements or remediation.

What is well supported for indoor mold is allergic and respiratory: rhinitis, worsened asthma, and infection risk in people with a compromised immune system.

The Centers for Disease Control and Prevention has stated there is no proven link between household mold and the rare systemic conditions frequently attributed to it. Reviews of indoor air quality and sick building syndrome have reached similar conclusions about purported mycotoxicoses.

Mold toxicity and mycotoxin poisoning

Mold toxicity, chronic inflammatory response syndrome and mycotoxin illness are not recognized medical diagnoses. People reporting fatigue, cognitive difficulty and diffuse symptoms in damp buildings are describing something they experience. The causal mechanism is what has not been demonstrated.

We say this plainly because both errors do harm. Overstating it sells work nobody needed and frightens tenants. Dismissing it leaves unwell people without a route to an answer. Neither is acceptable.

The gut, SIBO and digestive claims

Small intestinal bacterial overgrowth is a recognized gastrointestinal condition with recognized causes. The claim that household mycotoxin exposure causes it is not established, and the symptom lists circulating on this subject are not specific enough to point at any single cause.

If you have digestive symptoms, that is a question for a gastroenterologist. It is not a question a mold inspection answers, and any inspector who tells you otherwise has moved outside their competence.

Urine mycotoxin tests, and why we do not recommend them

Direct to consumer urine panels are widely sold and widely misread. 3 problems:

1. Not validated for diagnosing environmental exposure. These analytical methods were developed for agricultural and food safety work, not for establishing that a building made someone ill.
2. No meaningful reference range. Most people have detectable metabolites, mainly from contaminated food. A positive result does not distinguish your house from your diet.
3. The result cannot identify a source. Even an elevated value says nothing about which building, or whether a building was involved at all.

A positive panel is routinely presented to tenants and homeowners as proof their house is poisoning them. It is not proof of that, and a competent opposing expert will say so in about a minute.

What environmental testing can and cannot tell you

What it can do

Air and surface sampling establishes what mold is present in a building, at what concentration, and how that compares against an outdoor control taken the same day. Where a producing fungus is found growing, that is a defensible finding about the building.

Moisture mapping finds the water keeping it there, which is the part that actually has to be fixed.

What it cannot do

Environmental sampling does not measure what has entered a person. Nothing an inspector does establishes causation for a specific individual’s symptoms. That connection, if it exists, is made by a physician with the medical record, not by a laboratory report about a wall.

Direct sampling in buildings

It is possible to test dust or materials for mycotoxins specifically. It is expensive, the interpretive guidance is thin, and there are no health-based indoor standards to compare a result against. We will arrange it when a matter requires it, and we will tell you in advance that the result may not settle anything.

What drives mycotoxin production

Mycotoxin production is not constant. Certain Aspergillus molds and other fungal species produce more under stress, and warm and humid conditions plus a food source drive both mold growth and the natural occurrence of these compounds. Environmental factors decide how much of a toxin produced by a colony actually appears.

In a building, that means the same thing it always means: find the water.

When testing is worth it

• Visible growth, or a musty odor with nothing visible
• After water damage, a roof leak or a flood
• A physician wants to know what a patient is being exposed to
• A landlord, insurer, buyer or court needs documentation
• Clearance is required before people move back in

None of those depend on mycotoxins specifically. The building question is the same either way: is there growth, how far does it extend, and what is keeping it wet.

What to do if you are worried

Deal with the water. Every mold problem is a water problem, and production requires the mold to be growing in the first place.

See a physician, and bring the pattern rather than a symptom list. Symptoms that ease within a day or two of leaving and return on coming back are the most useful thing you can report.

Be careful what you buy. This subject attracts expensive protocols aimed at frightened people. Ask anyone selling you something what evidence supports it, and what result would tell them they were wrong.

Get the building measured by someone with nothing to sell. That is the part we do.

Common questions

How do you tell if you have mycotoxins?

You cannot establish it reliably from a home test. Acute exposure at agricultural doses is a clinical picture a physician recognizes. Ordinary indoor exposure is not something a urine panel can demonstrate.

What foods are high in mycotoxins?

Improperly stored grain, tree nuts, dried fruits, coffee and apple products are the usual subjects of food safety monitoring. Regulation and testing keep commercial levels low in most markets.

How do you get rid of mycotoxins?

In a building, by removing the mold growth and correcting the moisture that allowed it, which is remediation work done by a licensed contractor. That will never be us.

How long do mycotoxins stay in your body?

Most are metabolized and excreted within days. That is another reason a urine result is a poor guide to a building.

Should I get a urine mycotoxin test?

We do not recommend it as evidence about a building. Discuss it with a physician if you want to, but do not treat the result as proof of where anything came from.

Get a measurement, not a verdict

We provide independent mold inspection, laboratory testing and air quality testing across Orange County, Los Angeles and Pasadena.

We inspect and test only. We never perform remediation and take no fee from any cleanup, so when a result comes back unremarkable we have every reason to say so.

Where this fits

• Symptoms of black mold exposure, what the evidence supports and what it does not, marked as what each one is
• Independent laboratory mold testing