Toxic black mold, the informal name of Stachybotrys, is the most widely recognized danger in damp buildings. It’s not the only mold that can cause allergy, other forms of inflammation, and toxicity. But it is especially potent and the focus of this article is what makes Stachybotrys extraordinarily harmful.
Stachybotrys grows only in conditions of high dampness. Its preferred nutrient source is cellulose, a building material found in fiberboard, gypsum board, and paper. With this substrate and moisture, Stachybotrys can germinate, a process in which its spores can grow and develop into new fungal organisms.
Uniquely Toxic Toxins — Lung Bleeding and Inflammation
Stachybotrys is an effective toxin-former. As a hydrophilic water-loving mold, the damp conditions that enable its growth and enable its toxin formation. About one third of Stachybotrys strains produce a toxin known as macrocyclic trichothecenes, one of the most dangerous toxins in the fungal world, which exerts its effects by disrupting protein formation, triggering inflammation, and killing cells.
In infants, Stachybotrys can cause a catastrophic, including fatal, lung bleeding condition known as idiopathic pulmonary hemorrhage. The CDC acknowledges a “possible association” which is understating the matter given the replicable research performed on this topic. For example, four-day-old mice subjected to Stachybotrys spores and toxins develop lung hemorrhage.
Of note, this condition would not develop in the mice subjected to Stachybotrys in which the toxins had been removed. This finding proves that the lung hemorrhage is a probable direct toxic effect.
Stachybotrys can also form at least seven forms of a toxin known atranone. Atranone has an inflammatory effect and increases cytokines such as tumor necrosis factor-alpha and interleukin-6. Like the macrocyclic trichothecenes, atranones can inflame the lungs. But it does not typically cause lung hemorrhage. About one-third of Stachybotrys forms macrocyclic trichothecenes and about one-third form the less virulent atranones.
It Ain’t Just Toxins — Other Biologically Active Products in Stachybotrys
The toxins act along with and in combination with other biologically active products that contribute to health harms. These include:
- A class of proteins called hemolysins which cause bleeding by poking holes in red blood cells. Stachybotrys makes a type of hemolysin called stachylysin, a new protein first discovered in the in the homes of infants from children suffering from lung hemorrhage in an outbreak in Cleveland.
- Another class of proteins, called proteinases, which cause inflammation. These proteinases erode collagen tissues—including the delicate epithelial cells lining the airway.
- Beta-glucans is a common cell wall component of mold that is not unique to Stachybotrys. This complex sugar molecule (polysaccharide) inflames the body by stimulating an immune receptor dectin-1.
- Stachybotrys form up to 40 different spirocyclic drimanes, a harmful compounds that disrupts metabolism, the immune system, and blood flow—as well as having toxic effects on cells and the immune system.
- Toxic gasses called microbial volatile organic compounds, which causes irritation to the eyes, nose, throat, and lungs. These gasses infiltrate and injure the central nervous system as they readily absorbed into the brain.
A Toxic Stew — Associations with Other Organisms
One of the overlooked aspects of Stachybotrys health harms is this mold does not grow alone. The saturated damp conditions that foster its growth also promotes the rise of other molds, along with bacteria. One study detected between 170 to 300 species of mold and bacteria in the air of a shopping center.
Bacteria are more dependent on damp conditions that most molds and require the same level of water saturation as Stachybotrys to develop. Actinobacteria, a gram positive bacteria, have members that produce more inflammation than any harmful mold—including Stachybotrys!
Gram negative bacteria and some actinobacteria have cells a toxic cell wall made of lipopolysaccharides. Gram negative bacteria also produce other endotoxins, aside from LPS. Endotoxins can provoke a strong immune response.
The harmful elements of bacteria and mold act in a synergistic manner that causes harm that is greater than the sum of its parts. For that reason, building hazard is best understood as a harm arising from numerous biological elements and involving numerous injury mechanisms.
Yike, I., Miller, M.J., Sorenson, W. et al. Infant animal model of pulmonary mycotoxicosis induced by Stachybotrys chartarum . Mycopathologia 154, 139–152 (2002). https://doi.org/10.1023/A:1016098331428
James J. Pestka, Iwona Yike, Dorr G. Dearborn, Marsha D. W. Ward, Jack R. Harkema, Stachybotrys chartarum, Trichothecene Mycotoxins, and Damp Building–Related Illness: New Insights into a Public Health Enigma, Toxicological Sciences, Volume 104, Issue 1, July 2008, Pages 4–26, https://doi.org/10.1093/toxsci/kfm284