Ochratoxin A from mold in your home

Ochratoxin A, explained

Which molds make ochratoxin A

Ochratoxin A comes from two of the most familiar mold groups, which is part of why it shows up so often on panels. Within each group, only certain species, and only some strains of those species, are known producers.

Mold group	Known producers	Notes
Aspergillus, ochraceus group	Aspergillus ochraceus, A. westerdijkiae, A. steynii	Yellow to ochre colonies. The toxin is named after A. ochraceus.
Aspergillus, black group	Aspergillus carbonarius, some A. niger strains	Common on fruit. Black, powdery growth.
Penicillium	Penicillium verrucosum, P. nordicum	Tolerate cooler temperatures. Associated with stored grain and cured meats.

Many common indoor Aspergillus and Penicillium species aren’t known to make ochratoxin A at all. That’s why a dust DNA test showing a lot of Aspergillus and Penicillium doesn’t automatically mean ochratoxin A is present, and why the panel is worth running.

Why it’s so persistent

Chemically, ochratoxin A is a chlorine-containing ring structure linked to the amino acid phenylalanine. It holds up well to heat and to many ordinary cleaning conditions. In food processing, cooking and roasting reduce it only partly. In a house, that stability means it can stay in dust and materials long after the mold that made it has died.

You may see it described in the context of health research. The International Agency for Research on Cancer classifies ochratoxin A as possibly carcinogenic to humans (Group 2B), a rating based mainly on animal studies and dietary exposure. That classification doesn’t describe the risk from any particular house, and it isn’t something we can interpret for your family. Your doctor can.

How it gets into a home

• Damp building materials. Drywall, wood, carpet and insulation that stayed wet long enough for Aspergillus or Penicillium to grow.
• HVAC dust. Growth in or near the system, and dust it collects from across the house. See mycotoxins in HVAC systems.
• Stored goods. Grains, coffee, dried fruit, bulk pet food or birdseed stored in a damp basement or garage.
• Belongings from somewhere else. Furniture or boxes moved in from a moldy home can carry contaminated dust with them.

If stored food was in an affected area, our page on food stored in a moldy house covers what’s usually kept and what’s usually discarded.

What a positive dust result tells you

A detection means the toxin was in that dust sample at a measurable level. It doesn’t say where the source is, and on its own it doesn’t say whether the level is unusual. Compare it with other rooms, with the molds found in dust DNA testing, and with the lab’s reference data if it provides any. Our guide to reading mycotoxin test results goes through units, detection limits and flags.

Look at the other toxins on the report too. Ochratoxin A alongside citrinin points toward Penicillium, since some species make both. Ochratoxin A with sterigmatocystin suggests a mix of Aspergillus growth on damp materials. Ochratoxin A alone, in a house with a damp storage room, makes stored goods a stronger suspect. None of these patterns is proof, but each one tells you where to look first.

Getting it out

Ochratoxin A is removed the same way as other mycotoxins, with extra attention to storage areas. Moisture is corrected, contaminated porous materials are removed under containment, dust is captured with HEPA vacuuming and damp wiping, and remaining surfaces are treated. We use plant-based enzyme products from US Enzyme for that treatment. Clearance testing then confirms the result.

We remove mold and mycotoxins from buildings. We don’t diagnose or treat medical conditions, and nothing here is medical advice. If you have symptoms, please work with a doctor. With your permission, we’re glad to share test results with them.