Health issues of occupants in mold-infested houses are reported on a regular basis.  Recent concerns focus on mycotoxins, a secondary metabolite synthesized by mold.  Thorough mold sampling can provide credible counts and classification of molds. A patient’s health, and what effects their health, requires relevant biomarkers and exposure study.   

Mycotoxins secreted from molds have been blamed for many symptoms that are subjective and difficult to quantify.  There is no scientific evidence mycotoxins are associated with autoimmune diseases or other conditions.  In fact, there is no evidence that the presence of mycotoxins in the air is enough to cause any known disease.  

Molds and mold spores legitimately cause allergies and those corresponding symptoms.  Mold spores can trigger asthma.  Certain specific molds such as Aspergillus can be a cause of hypersensitivity pneumonitis.  In immunocompromised hosts, both dermatologic and systemic infections can result from any number of molds. 

Techniques such as testing homes for mold spores, measuring “mycotoxins” in the urine, and testing patients for Immunoglobulin G (IgG) to mold have NOT been validated for testing of any clinical disease.   Collectively, the data may be analyzed to reach a characterization of the exposure to a mycotoxin in that indoor environment, but some consider the cost of such testing an unnecessary cost on patients desperate for an actual diagnosis. 

Mold mycotoxins that pose a known health hazard to humans are associated with mold-contaminated food and feed.  Concerns about exposure to mycotoxin-producing fungi in indoor environments and damp homes and buildings revealed that the principal mycotoxins that contaminate food and feed are rarely if ever found in indoor environments.    

Although the Penicillium and Aspergillus genera are major contaminants of both food/feed and damp buildings, the species and hence the array of mycotoxins are quite different in each of these environments.  Species of Aspergillus and Penicillium prevalent in the indoor environment produce relatively low concentrations of mycotoxins. 

The mycotoxins of these indoor species and less common mycotoxins from Stachybotrys and Chaetomium molds are discussed in terms of their health effects and the need for relevant biomarkers and exposure study.   

Fungal growth in buildings starts at a water activity a(w) near 0.8, but significant quantities of mycotoxins are not produced unless a(w) reaches 0.95.  Pure water has a water activity of 1.0. 

Stachybotrys generates particularly high quantities of mycotoxins in water-damaged buildings. These mycotoxins are carried by spores and can be detected in air samples with high spore concentrations.  

Further exasperating the quantitative, most accredited mold sampling laboratories will group Aspergillus and Penicillium genus’ together, along with any other like mold that shares those physical characteristics.  The classification is “Aspergillus, Penicillium, Like”.  It is worthwhile to note that this grouping is due to physical characteristics as well as being the most common molds.     

The worst-case scenario for homeowners is a series of water events that promote fungal growth and mycotoxin synthesis, followed by drier conditions that facilitate the liberation of airborne spores and hyphal fragments.  

MOLDS known to produce MYCOTOXINS: 

Mycotoxin List

In conclusion, to determine if a mycotoxin exposure is a result of a water damaged building, the mycotoxin must be identified by the effected occupant’s doctor.  The identity of the mycotoxin can be traced back to a specific mold genus and species.  The building can next be tested for mold and those molds identified and classified.   It is a process of collaboration and reverse engineering to determine the mycotoxin, the exposure and the corrective action.