How Dangerous is Brown Hairy Mold Found in Bathrooms?

Photos of a brown hairy bathroom mold
Possible presence of Stemonitis sp. - a myxomycete in bathrooms and on OSB subfloors
Brown mold found on bathroom floor tiles
Brown hairy mold found under carpeting
Brown hairy mold found growing on subfloor materials
Questions & Answers about the identification, cause, & cure of brown hairy mold and other brown bathroom molds.
References

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Brown hairy mold in bathrooms (and on OSB subfloors): this document gives advice on identification of and health risks of brown hairy mold found in bathrooms (and other building areas), including brown hairy Stemonitis sp. mold found on bath floor tiles, under carpeting, on wood subflooring.

Identifying & Removing Dense Brown Hairy Mold Found On Bathroom Floor & Under Carpeting

Here we also discuss how to address the risk of further hidden bathroom mold, and we cite references on the toxicity of Stemonitis sp. - a brown hairy myxomycete mold found on OSB, wood subfloors, and in some bathrooms such as the bath floor shown in our page top photograph. This article series helps identify the presence of or locate the probable sources of mold reservoirs in buildings, and helps decide which of these need more invasive, exhaustive inspection and testing.

This article series on evaluating, removing, and preventing types of mold on various bathroom surfaces begins at BATHROOM MOLD. FIND MOLD in buildings, HOW TO describes how to find mold and test for mold in buildings, including how and where to collect mold samples using adhesive tape - an easy, inexpensive, low-tech but very effective mold testing method. (See TEST KITS for DUST, MOLD, PARTICLE TESTS for details).

Also see Brown Mold for more general questions and answers about brown mold found in buildings and an answer to "should I buy a home that has a mold problem?"

Question: what is this hairy brown mold found in my bathroom? Is brown hairy mold dangerous? How do I get rid of it?

I live in Melbourne Australia and I have a major issue with my bathroom floor. Please see my brown hairy mold photographs (below). The images are of brown mold growths on the bathroom floor, & afterwards when I had scraped them off the floor.

I do understand that no competent expert would pretend to ID mold [or any other microscopic particle] from just a field photo.

But I have no idea what I'm dealing with and of course am concerned for my health and my family's. Can you tell me please - is brown hairy mold dangerous? When I scraped the protrusions off the bathroom floor, it turned into a powder & hair like structures stood on end. I would be most grateful if you could please tell me what this could be and if it is dangerous.

I'm wanting to send a specimen away for analysis & hope that I can locate a government organisation in Australia, such as the Agricultural Department, hopefully they can do this at no cost. - G. P., Melbourne, Australia

Brown hairy bathroom mold under carpet (C) GP DF

Brown hairy mold on bathroom floor (C) GP DF

Reply: Examination of fungal material in an aerobiology lab is needed for sure identification of mold

Your photos are blurry and no competent expert would pretend to identify a mold genera or species just from email photos.

But with that caveat stated, the pattern and character of the mold in your photos resembles like a fungus Stemonitis sp. [1] - see Brown Mold and also at Rental Apartment Mold Safety Advice where we include photographs of Stemonitis sp. found on a bathroom floor and growing on oriented strand board (OSB) or "waferboard" in a basement.

Enlarging your photos [click any image to see an enlarged version] we see the mold was thick under carpeting (above left) meaning that in at least this area of the building, mold growth, including in hidden cavities such as walls, floors, ceilings, is likely to be extensive.

Watch out: And one would certainly expect other leak damage; that "wrinkled" looking floor baseboard trim board - if that's what it is in photo #1 at above left - means there have been leaks and probably rot.

If the mold test lab or aerobiology lab technician who examines a mold test sample you provide is familiar with myxomycetes, s/he should easily recognize the fungus from an actual sample. - you can use the clear adhesive tape sampling procedure at TEST KITS for DUST, MOLD, PARTICLE TESTS and send the sample to a qualified local lab of your choice [not to us].

Some Brown Hairy Molds are Probably Harmless

Stemonitis sp. is a Myxomycete ( a class of fungus) that is not listed in our MOLD ATLAS & PARTICLES INDEX nor in the authoritative Atlas of Clinical Fungi, deHoog et als. as a known toxic mold, though it is commonly described in mushroom field guides such as the National Audobon Society's Field Guide to Mushrooms [1]

But as we warned you earlier, having so much fungal growth and leakage as we saw in that lifted-carpeting photo, you should expect that other genera/species are likely to be present even if you don't see them yourself from a superficial inspection.

Watch out for Other Leaks & Hidden Mold

Watch out: At a minimum you'd be smart to assume there are allergenic molds present and if there is more than about one square meter of moldy material, to use appropriate protection measures during cleanup as well as, of course, finding and correcting the leaks that led to these conditions.

As we explain at BATHROOM MOLD, mold may be found growing on wood subfloors under bath floor tiles or sheet vinyl flooring if the bathroom floor has been wet or flooded. If a ceramic bath tile floor has become loose or if bathroom floor carpeting has been wet (as one would expect), we suggest exploring for damaged subfloors - otherwise simply repairing the tiles or replacing moldy carpeting may not be a durable fix.

If the bathroom is not on a basement or slab, inspect the ceiling areas below the bathroom for leak stains. Stained areas of drywall ceiling below a leaky bathroom or bath fixture usually merit further investigation.

You will want to study the building carefully to decide on the building points at most risk of having been wet from leaks due to construction details or other site observations. That's where one would make a test cut, remove carpeting, or otherwise explore further for hidden mold.

You might want to review FIND MOLD in buildings, HOW TO and also HIDDEN MOLD, HOW TO FIND.

See ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD on what to do about mold

We frequently add text and photos to this series of articles. See MOLD APPEARANCE - WHAT MOLD LOOKS LIKE and also to avoid spending on harmless non-mold debris see MOLD APPEARANCE - STUFF THAT IS NOT MOLD. Readers should also review Mold in Fiberglass Insulation in buildings at our The Mold Information Center - What to Do About Mold in buildings.

See Renovating to Avoid Mold Growth for specific tips that will mold-proof your bathroom, and see CONSTRUCTION DETAILS TO AVOID MOLD for a more broad list of details about mold-resistant construction in buildings.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
[1] Field Guide to Mushrooms, Lincoff, Gary H., Carol Nehring, National Audobon Society, Alfred A. Knopf, 2000, ISBN 0-394-51992-2
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Allergen Tests in buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
Building Floods: quick steps after a building flood or plumbing leak can prevent costly mold contamination
Classes of Mold: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
Fungi, Identifying Filamentous, A Clinical Laboratory Handbook, Guy St-Germain, Richard Summerbell, Star Publishing, 1996, ISBN 0-89863-177-7 (English) (buy at Amazon)
Mycology, Fundamentals of Diagnostic, Fran Fisher, Norma B. Cook, W.B. Saunders Co. 1998, ISBN 0-7216-5006-6 (buy this book at Amazon)

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