Mycotoxins: Toxins Produced By Some Molds
What mycotoxins are
Sources of mycotoxins
Health problems associated with mycotoxins
Decreasing exposure to mycotoxins
What Mycotoxins Are
Certain molds, such as Aspergillus, Fusarium, Penicillium, Chaetomium and Stachybotrys, (a more detailed list may be viewed from the Premium Content section) release chemicals during their metabolic cycle called mycotoxins, which can be toxic to humans and animals. These chemicals can be found in the mold spores, within the mold itself, and in the materials that the mold is growing. Inhalation of mold spores or dust containing mycotoxins can result in human exposure with potentially severe heath effects. A World Health Organization (WHO) publication on mycotoxins said that there are more than 200 mycotoxins produced by a variety of common fungi. Some include sterigmatocystin produced by Aspergillus versicolor; aflatoxins produced by Aspergillus flavus; fumonisins produced by Fusarium spp.; ochratoxins produced by Aspergillus ochraceus; and trichothecenes such as satratoxins produced by Stachybotrys chartarum.
Sources of Mycotoxins
Mycotoxins have been found in homes, agricultural settings, food, and office buildings. They have been found in many moldy construction materials and in buildings where building-related symptoms and building-related illness have been diagnosed.
Stachybotrys chartarum (also known by its synonym Stachybotrys atra) is a greenish-black mold that may produce a mycotoxin. Areas with excessive moisture that are subject to temperature changes are ideal for Stachybotrys to grow. Because the spores of Stachybotrys are wet and slimy, they do not get into the air easily unless the material it is growing on is physically disturbed (for example, if the material is cut or ripped out.) Most of the time, the spores of Stachybotrys get spread around by becoming attached to building or home dust, the bodies of insects or rodents or by getting washed away in running water.
Stachybotrys grows on wet material with high cellulose content, such as fiberboard, drywall, newspaper, gypsum board, wood, cardboard, paper, dust, lint, dropped ceiling tiles, wall paper and wallboard. Growth occurs when there is moisture from water damage, excessive humidity, water leaks, condensation, water infiltration, or flooding. Constant moisture is required for its growth. If you have had plumbing leaks, roof leaks, flooding in the basement, or sewer backup in the past year, look for mold or a musty odor. Stachybotrys does NOT grow on plastic, vinyl, concrete products, or ceramic tiles (like in the shower) and is NOT found in the green mold on bread.
After the area dries, the Stachybotrys will not continue to grow, but the black dust caused by the fungus can be sucked up by the furnace blower and spread throughout the house. Be sure and check your basement for mold even if you do not use your basement. If you do not have access to the basement, ask your landlord for assistance. Not all black mold is Stachybotrys, but moldy homes are not healthy homes. Therefore, it is not necessary to determine what type of mold you may have. All molds should be treated the same with respect to potential health risks and removal.
Some strains of Aspergillus flavus also produce mycotoxins. Aspergillus flavus grows on moldy corn and peanuts and can be found in warm soil, foods and dairy products. It has also been found in water-damaged carpets.
Health Problems Associated with Mycotoxins
There is no agreement among scientists about whether mycotoxins cause human health problems. Mycotoxins may have toxic effects ranging from short-term mucous membrane irritation to suppression of the immune system and cancer. Almost all the information related to diseases caused by mycotoxins concerns eating contaminated food. The health effects of ingesting moldy foodstuffs might include acute (immediate) and chronic (long-lasting) damage to the liver, kidneys, gastrointestinal tract, heart, central nervous system and the immune system.
However, mycotoxins are contained in some spores, as in the case of Stachybotrys that can be breathed in. Unlike allergens, mycotoxins can cause a response in almost everyone who is exposed to them. Since exposure to mycotoxins may present a greater hazard than that of allergenic or irritative molds, exposure should be minimized.
Animals who were injected with Stachybotrys spores had bleeding and death to the brain, thymus, spleen, intestine, lung, heart, lymph node, liver, and kidney.
Stachybotrys has been thought by some to be the cause of a bleeding lung illness called idiopathic pulmonary hemorrhage. However according to the National Center for Environmental Health, there are very few case reports that “toxic” molds (those containing certain mycotoxins) inside homes can cause unique or rare, health conditions such as pulmonary hemorrhage or memory loss. These case reports are rare, and a causal link between the presence of the toxic mold and these conditions has not been proven.
Some strains of Aspergillus flavus are capable of producing aflatoxins, which can cause cancer. These toxins may cause birth defects or liver damage.
Decreasing Exposure to Mycotoxins
Molds, whether they produce mycotoxins or not, need two things in order to live and grow:
Without these, the fungi cannot live. So to reduce the presence of mycotoxins in your home, you must do the following things:
Heating, ventilating and air-conditioning (HVAC) systems must be properly filtered and maintained.
Water intrusion must be stopped within 24 hours. Never overlook small leaks. Ignored small leaks are much more problematic than a properly handled major flood.
In a warm, humid climate, a building engineer should be consulted to make sure that a moisture barrier is properly installed and that no condensation will occur.
Install dehumidifiers in areas where humidity is constantly high. Keep relative humidity below 60%
Use a more efficient cleaning device, such as a high efficiency partculate air (HEPA) vacuum cleaner, for building cleaning and maintenance.
If large areas of contamination are present, consult a contractor with experience in removing asbestos and lead problems, as well as in biohazard remediation. These contractors would more likely know the proper steps to minimize exposure to both them as well as prevent the spread of the spores to other areas of the house.