What Is Stachybotrys?
Description and Natural Habitats
known by its nicknames of “black mold”, “toxic black mold”, “toxic mold”,
and “Stachy”, and
is a filamentous fungus occasionally isolated as a mold contaminant from
nature and indoor environments. The geographic distribution of Stachybotrys is
widespread. Stachybotrys mold spores and mold growth has been discovered in
contaminated grains, tobacco, insulator foams, indoor air, and water-damaged
extensive survey of indoor and outdoor S. chartarum air concentrations by
geographical regions in the United States found S. chartarum in 6% of the
1,717 buildings sampled in the period 1996-1998 (46% offices, 18%
schools, 13% hospitals, 4% homes, 0% industrial sites, and 18% other).
is a greenish black mold that, when active
and growing in a wet environment can look black, shiny, glistening and/or
grows on material with a high cellulose content or such as hay, straw,
wicker, and wood chips, as well as building materials such as ceiling tile,
drywall, paper vapor barriers, wallpaper, insulation backing, cardboard
boxes, paper files, fiberboard, the paper covering of gypsum wallboard,
particleboard, jute, dust, and wood when these items become water damaged.
Stachybotrys mold requires very wet or high humid conditions for days
or weeks in order to grow. Most mold spores can begin growing after just 24
hours of wetness, whereas Stachybotrys spores take at least 48 hours of
sustained wetness to begin growth.
Thus, Stachybotrys survives and grows best
in a continually wet environment such as a slow water leak in a wall, or in
a building suffering from ongoing high humidity levels. Excessive indoor
humidity resulting in water vapor condensation on walls, plumbing leaks,
spills from showering or bathing, water leaking through foundations or roofs
may lead to growth of many types of mold, including Stachybotrys.
Because Stachybotrys spores are rarely
airborne (unless Stachy mold
growth is dry and disturbed or the mold spores are attached to airborne dust
or other airborne particulates), Stachy is usually identified by
direct swabs, or lift tape samples of the mold itself with laboratory
analysis of the collected physical samples.
People can be exposed to S. chartarum via dermal contact, ingestion, and
inhalation. For the general population, the most common reports of
exposure involve water-damaged buildings, including homes, office
buildings, courthouses, hospitals, a hotel, and schools. Exposures leading
to stachybotrytoxicosis have been reported among farmers, workers at
facilities processing malt grain or reprocessing moldy grain, textile
mill workers using plant fibers, and workers at binder twine factories.
growth produces trichothecene mycotoxins known as satratoxins, and these
toxins may lead to pathological changes in animal and human tissues,
resulting in serious health and medical problems. Medical studies about the
health effects of Stachybotrys mold include---
R. Clark, and S. Williams. 1998. Stachybotrys, a mycotoxin-producing fungus
of increasing toxicologic importance. J Toxicol Clin Toxicol. 36:629-631.
Health Threat Exaggerated?
Other Mold Species
that Produce Potent Mycotoxins of the Type Produced by Stachybotrys
Many fungi (e.g., species of Aspergillus, Penicillium, Fusarium,
Trichoderma, and Memnoniella) in addition to
chartarum can produce potent mycotoxins, some of which are identical
to compounds produced by
Mycotoxins are fungal metabolites that have been identified as toxic
agents. For this reason, SC cannot be treated as uniquely toxic in indoor
(Courtesy of New York City Health Dept.)
Stachybotrys Species names
The genus Stachybotrys has a single well-known species, Stachybotrys
Additional species names include:
Stachybotrys alternans (obsolete)
This obsolete species is a synonym of S.
Stachybotrys atra (obsolete)
This obsolete species is a synonym of S.
S. alternans is an obsolete
synonym of this species.
S. atra is an obsolete synonym
of this species.
As seen in the pictures below, Stachybotrys mold is characterized by clusters of colourless to brown swollen phialides at
the tips of colourless to brown, sometimes branched, conidiophores. The
dark brown 1-celled spores (conidia) are produced successively from the
tips of the phialides and collect in wet masses. Species with spores in
chains are referred to Memnoniella. A strong decomposer of
cellulose and thus usually associated with decaying plant materials.
Pictures are courtesy of Botany
Department, University of Toronto
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