This list of fungi is intended to inform clients about fungi we most often report from the analysis of environmental samples. Our clients include industrial hygienists, environmental engineers, school personnel, physicians, toxicologists, microbiologists, laboratorians and other health professionals, environmental health and safety personnel, lawyers, and building owners.
This list describes fungi we often recover from indoor and/or outdoor samples. This list is not comprehensive nor is it a complete characterization of each fungus. References are provided for more detailed descriptions. Additional literature should be consulted if more information is required.
Fungi belong to a kingdom of organisms that includes dry and powdery growth forms often called "molds," and yeasts (soft and pasty growth forms). The term mildew is not used in our reports; mildews are a specific group of fungi causing plant diseases, such as powdery and downy mildew, and are not found growing in most indoor environments.
Categories were chosen to address the most frequently asked questions about each fungus. Some of the limitations of the information provided in this list are:
Health effects of some fungi or fungal toxins have not been studied or are not known. There is variation between species within a genus and between strains within a species.
Health effects resulting from fungal exposure may be dependent upon the health status of an individual.
Health effects resulting from fungal exposure may be dependent upon dosage and route of exposure.
The level of exposure to any fungal agent that may cause a health effect is not known.
Production of toxin and microbial volatile organic compounds (MVOCs) by fungi in an environmental sample is dependent upon many factors, such as substrate, relative humidity and temperature; the relative importance of each of these factors in toxin production is poorly understood.
Indoor and outdoor microbial environments are complex, dynamic and transient in nature, and sampling results will change with time. Viability of bacteria and fungi is influenced by environmental conditions such as relative humidity, available nutrients and temperature. Important microbial ecology factors, such as the presence of competing bacteria, fungi, production of antifungal and antibacterial metabolites, and insects greatly influence viability.
None of the fungi on this list are strict human pathogens. However, a few fungi on this list are able to grow at body temperature and have the potential of causing opportunistic disease. That is, they are capable of causing disease under conditions which favor their growth (such as trauma, burn, chronic lung disease, uncontrolled diabetes) or when the hosts’s immune status is altered (decreased white blood cells, chemotherapy, prolonged corticosteroid use). Some criteria used to establish a fungus as the etiologic agent of opportunistic human disease are:
Isolation of the fungus from the diseased site, especially if found in multiple specimens (samples).
Demonstration of the fungus in histologic preparations from the patient.
Disease symptoms compatible with a fungal infection.
Absence of other pathogenic agents or conditions.
Disease responsive to anti-fungal treatment.
These determinations should be performed by licensed health professionals in a clinical setting.
Glucans (beta-1,3-glucans) are major structural components of fungal cell walls. They are being investigated as contributors to symptoms reported in buildings. Some effects may be headache and non-specific respiratory symptoms.
Microbial volatile organic compounds (MVOCs) characterized as fruity, flowery, musty, earthy, rotten and sour odors, may be produced during active growth of some fungi and actinomycetes (e.g., Streptomyces species) and other bacteria. Some MVOCs have been found to be irritating to vertebrates.
Mycotoxins have been studied primarily in foodstuffs, and limited studies on respiratory exposure have been conducted in laboratory animals. Very little is known about inhalation exposure to mycotoxins in humans.