I have had several questions about mycotoxins during the past month, including one that led me to review the World Health Organization's (WHO) recent finding on this subject, as well as several other recent publications. I think the confusion resulting from these documents is this. They do conclude that mycotoxins CAN cause many of the types of effects that are part of indoor symptom syndromes. They don't say that they DO cause these effects.

The WHO document says, "The epidemiological evidence is not sufficient to conclude causal relationships between indoor dampness or mould and any specific human health effect..." The document does say that there is epidemiological evidence for associations between exposure to fungi and asthma development, asthma exacerbation, current asthma, respiratory infections (except otitis media), upper respiratory tract symptoms, cough, wheeze and shortness of breath.

The document also states that here is clinical evidence (i.e., evidence from clinical tests that are specific for the organisms) for specific microorganisms causing hypersensitivity pneumonitis, some fungal infections, humidifier fever, and inhalation fevers. Only toxicological data in laboratory animals is presented that relates mycotoxin exposure to health effects, and the document repeatedly cautions that dose must always be considered and that laboratory animals are generally exposed to far higher mycotoxin doses than occur in damp indoor spaces. A literature search using the Web of Science (which includes the National Library of Medicine) revealed no publications that contradict these statements as of August 2010.

The fact remains that no research has documented than anyone has ever been exposed to enough mycotoxin from exposure to indoor fungal growth to actually cause any of his/her symptoms with the possible exception of agricultural environments. In fact, there are no publications that I can find that actually document the amount of mycotoxin exposure in a moldy indoor environment.

Does this mean that such effects do not occur? Not necessarily, but I would expect them to be quite rare. Documentation of such effects awaits large studies that measure specific exposures to individual mycotoxins and to mixtures of mycotoxins, and relate these exposures to specific health effects.

This article originally appeared in the February 2011 issue of Indoor Environment Connections. Reprinted by permission.

About Dr. Harriet Burge Dr. Harriet Burge is EMlab P&K's Director of Aerobiology and Chair of EMLab P&K's Scientific Advisory Board. Widely considered the leading expert in indoor air quality (IAQ), Dr. Burge pioneered the field more than 30 years ago. She has served as a member of three National Academy of Sciences committees for IAQ, including as Vice-Chair of the Committee on the Health Effects of Indoor Allergens. View Dr. Burge's Curriculum Vitae. Read "Ask Dr. Burge" articles

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