Toxic Mold Syndrome: Separating Fact from Fiction

Fungi are present in all human environments, both indoors and outdoors, but most fungi do not cause disease in humans. Adverse health effects of fungi (or molds, which are a type of fungi) are thought to occur through infection, allergic responses or toxic effects from substances called mycotoxins. These fungal substances enable them to grow more efficiently and provide protection from other microorganisms like bacteria (penicillin is an example). In the past, concerns about the harms of mycotoxins were related to ingestion of these substances in contaminated crops, with a range of findings from skin irritation and abdominal distress to liver injury, low blood cell counts and an increased risk for certain cancers. Thankfully, severe toxicity from ingesting mycotoxin-producing fungi has largely disappeared with improved farming practices.

Between 1993 and 1994, a cluster of infant deaths from pulmonary hemosiderosis (bleeding in the lungs) in Cleveland, OH, garnered significant attention. These events were widely publicized, and researchers at the Centers for Disease Control and Prevention (CDC) reported that infants who died of pulmonary hemosiderosis were more likely to live in homes with detectable amounts of the mycotoxin-producing fungi Stachybotrys chartarum (commonly referred to as “black mold”) compared to living infants whose homes were in the same zip code. However, following this initial report and a second in 1997, a follow-up report in 2000 concluded that because of multiple issues with the way the data were collected and analyzed, there was insufficient evidence of a relationship between bleeding in the lungs in infants and Stachybotrys exposure (1-3).

It was also noted that other environmental exposures (such as tobacco smoke) in the infants’ homes may have contributed to the deaths. But by then, the media attention surrounding the story, coupled with a series of multimillion dollar lawsuits, made “toxic mold” a recognizable phrase. Reaching fever pitch in the early 2000s, Stachybotrys and other mycotoxin-producing fungi began to be blamed for a host of negative health effects. Inhalation of mycotoxins was purported to cause a range of nonspecific symptoms from fatigue and headache to respiratory symptoms, “brain fog,” and mood changes, often referred to as the “toxic mold syndrome” or within the integrative medicine community as “chronic inflammatory response syndrome (CIRS).”  

Multiple published studies have reported a relationship between mold exposure in indoor environments and many different types of symptoms. However, the findings from these studies are problematic for several reasons, including lack of comparison groups, reliance on self-reported symptoms and unreliable, unvalidated measures of mycotoxin exposure. For example, a study could be conducted within a school or workplace because of complaints of negative health effects. Investigators would go in and measure indoor fungal spores and then assess symptoms with questionnaires. Many studies like this found that symptoms were associated with increased fungal spores in the indoor environment. However, they did not compare these environments with schools or workplaces where people were not experiencing symptoms. It is possible that the fungal spore counts were not different between environments where symptoms were reported and where they were not, but without a comparison group, this cannot be known. Often, the only assessment of health effects in these studies was by self-report via questionnaires, without objective measurements or physical signs of disease reported. People who have a pre-existing belief that indoor mold is causing them problems may be more likely to report symptoms compared to those who do not share these beliefs.

Despite the many limitations of these studies, functional medicine providers began offering mycotoxin testing of urine to determine “exposure level” and detoxification programs to support the clearance of toxins from the body. For-profit companies began direct-to-consumer sales of urine mycotoxin test kits. However, these non-FDA approved mycotoxin tests are problematic because they lack standardization, can produce false positives or negatives and do not have established thresholds for what constitutes harmful levels of mycotoxins in the body. After a systematic review of all available evidence, both the Institute of Medicine and the World Health Organization published reports concluding that the available evidence was insufficient to support a relationship between mycotoxin inhalation and the range of nonspecific symptoms reported as toxic mold syndrome or CIRS.

There is a clear, well-established relation between damp indoor spaces and detrimental health effects (4,5). Unfortunately, the mechanism(s) driving the effects remains uncertain or controversial. Further, engineering science is still not able to clearly define what a “damp building” is. There is currently no universally accepted standard for safe levels of mold in indoor environments. Therefore, the CDC advises prompt removal of mold, regardless of its type, to minimize potential health risks. While mold can be a concern, it is important to be cautious when linking physical symptoms directly to mold exposure, especially when considering costly, testing methods that haven’t been proven. Consulting with certified professionals and following evidence-based guidelines is the best approach for managing mold-related health concerns.

Find out more about mold allergies.

References:
1. CDC. Acute pulmonary hemorrhage/hemosiderosis among infants in Cleveland, January 1993-November 1994.MMWR 1994; 43:881-3.
2. CDC. Update: pulmonary hemorrhage/hemosiderosis among infants---Cleveland, Ohio, 1993-1996. MMWR 1997;46:33-5.
3. CDC. Update: Pulmonary Hemorrhage/Hemosiderosis Among Infants --- Cleveland, Ohio, 1993-1996. MMWR 2000; 49:180-4.
4. Institute of Medicine. 2004. Damp Indoor Spaces and Health. Washington, DC: The National Academies Press. https://doi.org/10.17226/11011.
5. WHO Guidelines for Indoor Air Quality: Dampness and Mould. Geneva; 2009.

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11/12/2024