Allegations about adverse health symptoms associated with mold exposure have become the driving force behind the movement to assess the extent of mold in buildings and remediate its presence. However, there are those who believe major misinformation has been presented to the public. Therefore, it is important to examine well-established scientific and medical facts before making any decisions regarding this controversial topic.

Facility professionals can legitimately be concerned about concentrations of mold detected in indoor ambient air that are greater than 100 to 200 CFU/m3 or greater than 1000 spores/m3. And yet, there are no established threshold levels at which adverse health effects can be documented.

Therefore, a comparison of mold concentrations commonly found in indoor ambient air and those measured in the outdoors is an appropriate beginning guideline. Unless extensive water damage is evident, the majority of commercial structures have indoor ambient air levels below those detected in the outdoors. However, this varies with time of year, location of facility, and mold generated.

Under extreme circumstances, exposure to mold has been conclusively linked to a diverse range of adverse health problems. These problems are wide ranging. However, they arise as non-specific symptoms like fatigue. There have also been allegations of brain damage, but those links are not confirmed.

Three types of reactions have been documented as being associated with indoor (non-occupational) mold exposure: allergic responses (hayfever, asthma, and hypersensitivity pneumonitis), minor irritant effects, and infections in individuals with impaired immune systems.

Exposure to high concentrations of Aspergillus (a group of molds found world wide, especially in the autumn and winter in the Northern hemisphere) may lead to infection in some individuals. Also, when exposed to low to moderate levels of Aspergillus, immunocompromised patients (e.g., transplant patients, cystic fibrotics, chemotherapy patients) may develop infections.

However, even in these individuals, the risk is low. Mold present at typical indoor environmental levels has never been scientifically shown to cause any other illnesses aside from those previously mentioned (Robbins et al. 2000.).

There are many statements made about mold related illnesses, but very few can be backed up with conclusive evidence. What follows is a list of some of those misnomers, followed by the reasons why no definitive connection can be made.

Fiction. Stachybotrys is the most dangerous of molds and has been known to cause hemorrhages in the lungs of humans.

Fact. Three research papers show a connection between newborns with bleeding lungs and the presence of Stachybotrys in the indoor environment (Dearborne et al. 1997, Etzel et al. 1997, Montana et al. 1997). However, the findings of an association between this disease and exposure to Stachybotrys have been rescinded by the Centers for Disease Control and Prevention (CDC), because the study design was flawed.

As a result, data compiled in these studies was inadequate to support a hypothesis of a cause and effect relationship (CDC 2000). Moreover, no further clinical evidence of this disease has emerged despite the increasing number of buildings found to contain levels of the Stachybotrys mold species.

Fiction. Exposure to Stachybotrys and other fungi results in brain damage. Fact. Several investigators have associated the reporting of headaches, memory loss, lack of concentration, and other similar non-specific symptoms as being evidence of brain damage caused by alleged mold exposure (e.g., Gordon et al. 2001, Johanning et al. 1999). But there is no scientific or medical evidence that concentrations of Stachybotrys or other molds detected in the indoor ambient air (or present on building materials) can cause brain damage (Fung et al. 1998, Page and Trout 2001, Robbins et al. 2000, Terr 2001).

Fiction. Toxic molds cause adverse health problems.

Fact. The term toxic mold is itself a misnomer. Thousands of different compounds are produced by molds, and people are exposed-both indoors and out-to these compounds daily. A single mold can produce anywhere from several to a hundred mycotoxins that are considered potentially toxic to animals and humans (Gots and Pirages 2002). Several different molds may produce the same toxin.

Fiction. If Stachybotrys is detected anywhere in a building (i.e., in the indoor ambient air or within interstitial walls), extensive remediation is urgent.

Fact. It is highly unlikely that there is a building in which some Stachybotrys spores (albeit low in number) could not be detected if sufficient testing were conducted on building materials and within interstitial spaces. This mold has been detected in both indoor and outdoor ambient air in commercial buildings where occupants have not had any health complaints associated with the presence of mold (Baxter 1998, Harrison et al. 1992, Hawthorne et al. 1989, Shelton et al. 2002).

Thus, mere detection of Stachybotrys does not automatically require costly remediation. The need for remediation will depend upon the extent of mold growth, the extent of water damage, and the location of detected molds, i.e., in areas accessible to building occupants.

Fiction. Self reported symptoms are indicators of mold exposure.

Fact. Many epidemiological studies of mold do not have documented concentrations present in the building of concern (e.g., Gordon et al. 1999, Johanning et al. 1999). Rather, these studies rely on self reported symptoms as a surrogate of mold exposure. Because these self reported symptoms are non-specific, it is not possible to identify chronic diseases based on these symptoms alone. Such self reported symptoms are not valid surrogates of exposure.
Symptoms are frequently over-reported when people believe their health has been threatened.

A review of the scientific literature regarding self reported symptoms indicates that these can be unreliable when perceived hazards exist as a basis for confirming health problems.
Several authors have studied and reported upon the unreliability of self reported symptoms, particularly following perceived toxic exposures (Barsky and Borus, 1995 and 1999; Barsky, et al., 2001, Gots et al. 1992, Hopwood and Guidotti 1988, Lees-Haley and Brown 1992, Kaye et al. 1994, Lipscomb et al. 1991, Lipscomb et al. 1992, Logue and Fox 1986, Pennebaker 1994, Roht et al. 1985).

One important reason given for this unreliability is the phenomenon known as "reporting bias." (Last 1992, Hennekens and Buring 1987, Lipscomb et al. 1991, Logue and Fox 1986, Pennebaker and Epstein 1983, Pennebaker 1994.) This term is a standard epidemiological term and not meant as a pejorative. Rather, it refers to the normal human tendency to connect physical phenomenon with unrelated causes, particularly when the perceived cause is viewed as a health threat.

Fiction. Toxic fungal syndrome is associated with exposure to mold in the indoor environment.

Fact. Some promoters of allegations that exposure to mold has caused non-specific adverse health outcomes have coined the term "toxic fungal syndrome" or similar labels. There is no such standard or accepted medical terminology. This and other similar terms represent a collection of undocumented, self reported symptoms that have no established scientific or medical causal link to mold.

Fiction. Exposure to low level concentrations of mold result in adverse health problems.

Fact. As previously noted, there is no scientific or medical evidence that exposure to low concentrations of mold can result in significant adverse health outcomes. An illustration of the lack of a sound scientific basis is the extent of fungal exposure observed in occupational settings. Such occupational exposures, via handling materials of natural origin, can be extremely high.

For instance, fungi detected in the breathing zone of workers in a municipal waste composting facility reach levels of 8,200,000 CFU/m3 (Lacey and Crook 1988). In these highly exposed populations, however, there are no reports of brain damage, or of many of the other fungal diseases now common in current indoor mold attributions.

Clearly, mold has become a source of controversy in commercial buildings. While there are instances where IAQ testing, remediation, and risk communication are necessary, the first response should not be one of panic. By carefully evaluating and managing the medical and toxicological aspects, facility professionals can develop tactics to protect themselves, their co-workers, and their buildings.

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