Written by Robert Sheriff, MS, CIH, CSP and Henry P. Shotwell, Ph.D., CIH, Vice President
November 5, 2018, Updated June 2019
Mycotoxins, Toxic Chemicals Produced By Molds
There has been a lot of talks recently about extremely toxic chemicals produced by molds, called mycotoxins. Testing/sampling and remediation companies, looking to make a fast buck, use the purple-est of prose in their advertising, hoping to separate you from your money. These advertisements have a grain (no pun intended) of truth in them but are slanted to plant the seeds of fear in your mind. Three of the most commonly encountered mycotoxins are produced by Streptomyces griseus, better known as Streptomycin; Claviceps purpura, better known as Lysergic Acid Diethylamide or LED and Penicillium chrysogenum which produces penicillin.
Many other mycotoxins such as aflatoxins, satratoxins, trichothecenes, trichoverrols and many others, are indeed extremely toxic: by ingestion or infection, not by inhalation. Russia, in the late 19th century, again in 1928 and in the late 1940s saw an epidemic of diseases among poultry, pigs, horses and other livestock that had eaten highly mold-contaminated grains. These animal deaths were studied extensively and shown to have been caused by certain mold secondary metabolics: mycotoxins-again the route was ingestion not inhalation.
Adverse Health Effects
It has been suggested that adverse health effects can be caused by inhaling mycotoxins produced by molds contaminating homes, offices, and schools. To test this hypothesis, Bruce J. Kelman, Coreen A. Robbins, Lonnie J. Swenson, and Bryan D. Hardin published a research article in the International Journal of Toxicology (Jan. 2004, Volume 23, #1: pages 3-10) entitled “Risk from Inhaled Mycotoxins in Indoor Office and Residential Environments.” These authors noted that the epidemiologic evidence has so far been unable to show a cause and effect relationship between indoor mold and (non-allergic) toxic effects in humans. They calculated the maximum possible dose of mycotoxins that could be inhaled in 24 hours of continuous exposure to a high concentration of mold spores containing the maximum reported concentrations of aflatoxins B1 and B2; satratoxins G and H, fumitremorgans B and C, verruculogen and trichoverrols A and B. These calculated doses were then compared to the effects known to be caused by each of these mycotoxins.
None of these calculated mycotoxins doses were high enough to cause any adverse effect. The model showed how inefficient the delivery of mycotoxins is when mold spores are inhaled. The authors concluded that illness in humans caused by inhaling mycotoxins in home, school or office is most unlikely.
Jarvis & Miller, wrote in Applied Microbiology and Biotechnology (Applied Microbiol. Biotechnol. 2005 Jan; 66 (4): 367-72) “Mycotoxins as harmful indoor air contaminants,” state that the principal mycotoxins that contaminate food and feed (aflatoxins, fumonisins, ochratoxins A., deoxynivalenol and zearalenone) are rarely if ever found in indoor environments.
Robbins, et. al., in Volume 15, Number 10 of the Applied Occupational and Environmental Hygiene Journal of 2000 also found that current literature “does not provide compelling evidence that exposure (to mycotoxins) at levels expected in most mold-contaminated indoor environments is likely to result in measurable health effects.” Although the authors caution that case reports can’t be used to determine causation for an environmental agent, they state that such reports can be useful to identify the need for further investigation. They then present several anecdotal reports of the development of symptoms after exposure to massive amounts of mold. The reports suggested mycotoxins as a cause of the symptoms. In all cases, the patients recovered rapidly once the exposure ended.
So, what does all this mean? Lurid headlines warning of the extreme dangers of mycotoxins are probably right if you’re a Russian horse about to eat mold-contaminated grain. But if you’re a homeowner concerned about breathing mycotoxins or a worker in an office, all the evidence says you would have to have so much mycotoxin-producing mold in the air that it would look like a dust storm. And even then, you could expect to get nothing worse than flu-like symptoms which would go away after exposure is stopped. Mycotoxins are not likely to be a problem for you. At the most, individuals whose systems are already compromised due to illness (such as cancer) or taking autoimmune suppressors such as for a heart transplant may have a slightly increased risk of illness due to mycotoxins.
For all the hype about “toxic molds” and mycotoxins there is little, if any, evidence that a homeowner, apartment dweller or office worker could suffer disease from inhalation of a mold that produces a mycotoxin.
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