Mycotoxins - Toxic Molds
Mycotoxins are nonvolatile, relatively low-molecular weight secondary metabolic products that may affect exposed persons in a variety of ways. These compounds are considered secondary metabolites because they are not necessary for fungal growth and are simply a product of the primary metabolic processes. The functions of mycotoxins have not been clearly established, but they are believed to play a role in eliminating other microorganisms competing in the same environment. They are also believed to help parasitic fungi invade host tissues.1 The amount of toxins needed to produce adverse health effects varies widely among toxins, as well as each person's immune system.
Fungi that produce mycotoxins are referred to as toxigenic fungi. The most frequently studied mycotoxins are produced by species of Aspergillus, Fusarium, Penicillium, Stachybotrys and Myrothecium. However, toxins have been detected from many other fungi under certain growth conditions. The kinds and amounts of toxin produced depend on the fungal strain, the growing conditions, as well as the presence or absence of other organisms. Mycotoxins accumulate on fungal spores, cell fragments, and substrates (nutrient sources).
Fungi that produce potent mycotoxins are seldom abundant in outdoor ambient air. Most toxic exposures occur from indoor growth of fungi related to excessive moisture. Some mycotoxins are carcinogenic, some are vasoactive, and some cause central nervous system damage. Often, a single mycotoxin can cause more than one type of toxic effect.
Mycotoxins are chemicals (metabolites) produced by molds, which cause a toxic response in humans if ingested, inhaled, or in contact with skin. Mycotoxins can affect the immune system, nervous system, liver, kidneys, blood and blood clotting. Some mycotoxins are known to be carcinogens. Research is being conducted to determine how fungal mycotoxins may contribute to vague health symptoms experienced by those who live in environments with a high fungal load. Many fungi produce mycotoxins, both inside spores and on their surfaces. Killing spores does not disable the toxicity of mycotoxins. In fact, mycotoxins can be present on or in spores, whether the spores are dead or alive. Stopping fungal growth does not stop adverse medical symptoms. Both spores and hyphae can be allergenic and/or toxic.
Under damp conditions, specific species of fungi may produce mycotoxins like some of the following:
- Aspergillus versicolor
- Penicillium chrysogenum
- Penicillium expansum
- Stachybotrys sp.
- Aspergillus and Penicillium, which produce mycotoxins, are often present in homes following a flood or chronic moisture invasion. Stachybotrys chartarum will grow on very wet building materials which contain cellulose and low nitrogen content. Stachybotrys is associated with a very potent mycotoxin. In addition to unusual mycotoxin symptoms, exposure of Stachybotrys to the skin may also cause a rash.
- MVOCs, (Microbial Volatile Organic Compounds) are musty, moldy odors associated with fungi. Fungus release MVOCs as gases, as a result of life processes (farts). MVOCs are composed of alcohols, ketones, hydrocarbons, and aromatics. Porous building materials can absorb MVOCs, and release the odors over time. MVOCs may contribute to health effects in humans although valid information on long term or acute effects is lacking. Individuals can consult with their physicians, or allergists to inquire about individual health effects. It has been suggested that the MVOCs carry the mycotoxins during the evaporation process.
| Health Effects of Toxic Molds |
Allergic Fungal Sinusitis |
Ten Things You Should Know About Mold |