The Prevalence of Stachybotrys Chartarum
The Prevalence of Stachybotrys Chartarum
Stachybotrys chartarum, also called toxic black mold, gained notoriety when it was linked to several infant deaths caused by acute idiopathic pulmonary haemorrhage. The causal link was never confirmed however serious health concerns from exposure still exist. How common is Stachybotrys chartarum in water damaged buildings? What is the prevelance of Stachybotrys chartarum and how much of a risk does it present?
Stachybotrys chartarum has a greenish-black appearance and can look slimy because of a wet layer on the top. It can also appear dry and powdery in drier conditions. There are several molds that look similar to Stachybotrys chartarum and the only way to definitively identify Stachybotrys chartarum is to collect a sample and have it tested.
The growth of Stachybotrys chartarum depends on temperature, moisture, relative humidity and growth substrate. The Stachybotrys species can propagate over a wide range of temperatures, and require a moisture content of at least 15% in the substrate and a relative humidity of 70% to 90%.
Materials with high cellulose content such as straw, hay, plant debris, cereal grains, and various building materials such as fiber board and gypsum liner paper that become moist provide ideal growth conditions. Stachybotrys chartarum has also been isolated from other substrates including pipe insulation, gypsum, fiberglass wallpaper, and aluminum foil.
A recent study evaluating the prevalence of various mold species found that Stachybotrys was less common, being identified in approximately 13% of homes. In most studies, Stachybotrys has had a low prevalence, being present in less than 3% of samples. However, some recent research has suggested that it may be more common than initially reported. One reason is underreporting by the laboratories.
Stachybotrys is rarely found in isolation, nearly always occurring in the presence of other fungi. This is very important since many other mold species are capable of generating mycotoxins and current research indicates that volatiles from Stachybotrys chartarum may represent only a small portion of the total quantity present in problem buildings where other fungi exist. Cladosporium, Penicillium, and Aspergillus species are found more frequently in water damaged buildings and are often utilized by investigators as indicator species of mold contamination.
In agricultural settings where hay or straw has become saturated with water under aerobic conditions, Stachybotrys chartarum has been shown to flourish. Adult humans and animals exposed to Stachybotrys chartarum via inhalation in agricultural environments have developed health effects according to documented cases in Eastern Europe. The subsequent disease in farm animals and farm workers is mainly due to the potent mycotoxins produced by S. chartarum. Spores and mycelia from Stachybotrys species have been shown to contain trichothecene mycotoxins and prolonged inhalation exposure to trichothecene-containing dust particles, spores and mycelial fragments may lead to developing health effects related to toxin exposure.
In conclusion, in buildings with moisture intrusion, Stachybotrys chartarum competes poorly with other mold species; it grows best on substrates close to water saturation. Therefore the prevalence of Stachybotrys chartarum is low in most homes impacted by moisture intrusion. However, Stachybotrys chartarum can dominate in serious and usually catastrophic water infiltrations, such as from storms, pipe leaks and envelope and roof failures. In general, these situations are rare but could increase in frequency as storm events related to climate change become more common.
For more information regarding potential mold contamination and/or suspected exposure to Stachybotrys, contact ECOthink Group. ECOthink Group, LLC. has conducted hundreds of mold inspections throughout the tri-state area including Connecticut, New York and New Jersey. Our environmental professionals, mold experts and certified industrial hygienists (CIH) can provide the following services:
- Flood response services
- Moisture assessments
- Mold investigations / mold inspections
- Air testing for mold
- Testing for sewage contaminants
- Development of mold remediation specifications
- Mold remediation services
- Monitoring mold remediation
- Clearance testing
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