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Chaetomium — An Overlooked Danger

Due to the notoriety of Stachybotrys, the toxic mold Chaetomium is overlooked and under-recognized.

Similarities with Toxic Black Mold

Chaetomium and Stachybotrys have much in common.

They both consume cellulose-containing materials such as gypsum board, wallpaper, insulation, and straw. They both grow only at high levels of water saturation which typically result from leaking water pipes, defects in roofs or walls, flooding, or severe condensation. They both form toxins. Plus they both cause human health harms involving hypersensitivity syndromes, such as innate immune activation and allergy, and mycotoxicosis.

Chaetomium is a genusof fungi that includes about 95 species. The different species produce different types of mycotoxins. The high moisture that promotes its growth also provides the necessary hydration for it to make a range of toxins:

  • Sterigmatocystin poisons the kidneys and liver.
  • Chaetochromin is teratogenic, known for its toxicity to the developing embryo and fetus.
  • Chetomin and chaetocin is toxic to cells.
  • Chaetoglobosin, a toxin made by Chaetomium globosum, damages actin a structural component of cells.

Catch Me if You Can

Chaetomium spores are difficult to measure in air samples. Chaetomium is present in between 3 to 8.8% of air samples. Other studies have been unable to detect it by air samples, even when swab samples of surfaces have detected it. In one study that used genetic analysis, a highly precise methodology for determining fungal species, the swab rate of Chaetomium was 23%—but the air sampling rate of detection in that same study was 0%.

Why is Chaetomium so hard to measure by air sample?

  1. Hides Well — Chaetomium is normally found in cracks and cavities, such as the back side of wall paper. For this reason, it might not be seen until walls are open up for invasive investigation.
  2. Slimy Texture — Like Stachybotrys, Chaetomium produces spores along slime heads and the sticky texture makes it difficult for spores to rise into the air.
  3. Heavy Spores — If the spores do rise up, they are heavier than older mold spores and tend to settle down faster, evading capture by the air sampler inlet valve.
  4. Odd Shape — The football-shaped spore has only a small portion that can contact the common adhesive gel. As with a football reception, the spore has to hit the receiver in a certain way on the numbers in a narrow window of time.


Fogle, Matthew R., et al. “Growth and mycotoxin production by Chaetomium globosum.” Mycopathologia 164 (2007): 49-56.

Shelton, B. G., K. H. Kirkland, W. D. Flanders, and G. K. Morris. 2002. Profiles of airborne fungi in buildings and outdoor environments in the United States. Appl Environ Microbiol 68:1743-1753.

Vesper, S. J., C. McKinstry, C. Yang, R. A. Haughland, C. M. Kercsmar, I. Yike, M. D. Schluchter, H. L. Kirchner, J. Sobelewski, T. M. Allan, and D. G.Dearborn. 2006. Specific molds associated with asthma in water-damaged homes. J Occup Environ Med 48:852-858.

Udagawa, S., et al. “The production of chaetoglobosins, sterigmatocystin, O-methylsterigmatocystin, and chaetocin by Chaetomium spp. and related fungi.” Canadian Journal of Microbiology 25.2 (1979): 170-177.

Tsuchiya, Toshie, et al. “Effect of chaetochromin A, chaetochromin D and ustilaginoidin A, bis (naphtho‐γ‐pyrone) derivatives, on the mouse embryo limb bud and midbrain cells in culture.” Congenital Anomalies 27.3 (1987): 245-250.