About Stachybotrys chartarum
Stachybotrys chartarum (commonly called 'black mold') is the most notorious mold in the context of water-damaged buildings. It's a tertiary colonizer requiring very high water activity to grow, so it is generally associated with cellulose-containing materials that have stayed wet for a long time. It produces some of the most potent mycotoxins known: macrocyclic trichothecenes including satratoxins G and H, roridin E, and verrucarin J. These toxins are potent inhibitors of protein synthesis in virtually every cell type, and animal studies have demonstrated nasal and pulmonary toxicity, olfactory nerve damage, apoptosis of brain neurons, and severe lung inflammation. As one of the five HERTSMI-2 species, it adds points to that score even at low levels. A dust result cannot show whether any material is wet now. An on-site inspection by a qualified, independent professional is the way to check.
Ecology and water requirements
Stachybotrys chartarum is classified as a tertiary colonizer in the ecological succession that follows water damage in indoor environments. Primary colonizers (xerophilic Penicillium and Aspergillus species) establish first on damp materials at relatively low water activity; secondary colonizers (Cladosporium) follow as moisture stabilizes; tertiary species like Stachybotrys chartarum require sustained, high water activity (Aw 0.94 or above)[2] and typically appear after weeks to months of continuous wetness. Because of this requirement, its detection in indoor dust samples is one of the more diagnostic available signals of significant, sustained water intrusion[4], distinct from elevated humidity alone. The species cannot establish on materials that dry between wetting events; persistent water contact with cellulose-containing or other organic substrates is required.
Mycotoxin biology
Stachybotrys chartarum produces a range of secondary metabolites with biological activity. The compounds documented in the literature for this species are listed in the chips below. Mycotoxin production is not uniform across all strains and is influenced by substrate, temperature, and water activity[3]. The same isolate may produce substantially different metabolite profiles on drywall paper versus wood versus settled dust[6]. DNA-based detection via the ERMI panel identifies species presence but does not directly measure mycotoxin presence; detection of a mycotoxin-producing species in household dust does not establish exposure to that mycotoxin at any specific concentration.
Detection in dust versus visual inspection
DNA-based detection of Stachybotrys chartarum in settled household dust (the basis of the ERMI panel[1]) integrates spore material from current and recent growth in the home, capturing exposure history over weeks to months. A positive detection in dust does not necessarily indicate currently-active growth at the time of sampling; conversely, an active growth site can produce relatively low dust spore counts if the spores are not being aerosolized (sealed wall cavities, behind vapor barriers, or under flooring). Interpretation requires considering the dust signal alongside building inspection, occupant symptom history, and the broader pattern of species detected on the panel.
Where it’s typically found
Stachybotrys chartarum is documented on the following substrates and locations:
- Paper-faced drywall
- ceiling tiles
- wood paneling
- cardboard
- canvas
- paper products
- all requiring sustained wetness
Mycotoxins
Compounds documented as produced by Stachybotrys chartarum (presence and quantity vary by chemotype, strain, and substrate):
Mycotoxin production is not uniform across all strains and is influenced by substrate, temperature, and water activity. Detection of a mycotoxin-producing species in household dust does not directly establish exposure to that mycotoxin at any specific concentration.
On your ERMI report
Stachybotrys chartarum is one of the five HERTSMI-2 species, a subset of the 26 EPA water-damage indicator species (sometimes labeled "Group 1" in EPA documentation). On a HERTSMI-2 score, it is weighted heavily, and elevations contribute multiple points to the total. HERTSMI-2 was developed by Dr. Ritchie Shoemaker as a screening tool for assessing whether a water-damaged building is safe to re-enter for individuals previously sickened in such environments[5]. Whether the level detected in any specific home is concerning depends on the broader pattern: which other species are elevated, the water-activity profile of the elevated species, the home's climate context, and (where relevant) the occupant's sensitivity history. Our interpretation report puts Stachybotrys chartarum in that broader pattern.
Mycotoxins and extended panels
Related reference pages: the mycotoxins Stachybotrys chartarum can produce, and the extended-panel species most closely related to it:
Related species
References
- Vesper SJ, McKinstry C, Haugland RA, et al. Development of an Environmental Relative Moldiness Index for U.S. homes. J Occup Environ Med. 2007;49(8):829–833.
- Pitt JI, Hocking AD. Fungi and Food Spoilage. 3rd ed. New York: Springer; 2009.
- Nielsen KF. Mycotoxin production by indoor molds. Fungal Genet Biol. 2003;39(2):103–117.
- Institute of Medicine. Damp Indoor Spaces and Health. Washington, DC: National Academies Press; 2004.
- Shoemaker RC, Mark L, McMahon S, Thrasher JD, Grimes C. Research Committee Report on Diagnosis and Treatment of Chronic Inflammatory Response Syndrome Caused by Exposure to the Interior Environment of Water-Damaged Buildings. Surviving Mold; 2010.
- Miller JD, McMullin DR. Fungal secondary metabolites as harmful indoor air contaminants: 10 years on. Appl Microbiol Biotechnol. 2014;98(24):9953–9966.