Indoor Molds

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Harmful Effects of Indoor Molds

There is much yet to be learned about the health effects of chronic inhalational exposure to indoor molds . Only a handful of decades have passed since improvements in building construction began making indoor spaces more airtight. Prior to this, excess production of mold spores and/or mycotoxins was likely diluted by regular exchange between indoor and outdoor air. Unlike other toxigenic substances, inhaled mycotoxins in residential settings have only been studied for the past 30-40 years and without specific markers of either exposure or disease. The inability to definitely link the presence of the agent in the environment to human exposure data and subsequently to molecular alterations and disease leave many unconvinced of the deleterious effects of mold/mycotoxin exposure.

Figures 1 and 2 summarize current issues in establishing mycotoxin/mold spore exposure as a cause of undesirable health effects.

In addition to information presented in the following sections about the particular effects of mold toxins, it is important to keep in mind the circumstantial evidence that also exists. Present technology and human knowledge does not provide a complete understanding of the mechanisms by which molds affect human health. However, molds have certain requirements to sustain life. Moisture, temperature, and particular nutrients. Additionally, some molds produce toxins to gain a competitive edge over nearby microorganisms in an effort to establish a biological niche. These toxins have irrefutably been shown to exhibit considerable cytotoxicity. When these substances come into contact with other cells – whether of microorganisms or human, cell death will occur. Humans may end up as innocent bystanders in the mold’s efforts to thrive.

Figure 1.Measuring toxigenic mold exposure and health

Agent in Environment	Human Exposure	Molecular Response	Symptoms - Disease
Possible to determine, typically not measured until after onset of ilness. these later measurements may not be reflective of the environmenta conditions present at the time illness was developing (changes in moisture, temperature, food sources, or other growing microorganisms can all affect mold growth. Inconvenient for typical consumer Can vary depending on measurement methods used. Can make comparisons difficult between studies using different testing methods.	Often measured via self-reported mold and/or moisture problems at home or workplace as a proxy for mold-specific indicators of exposure and dose. Results of environmental testing in the home or workplace are also used as a proxy for indoor mold exposure. Both measures are very crude measures of dose. Not yet possible to measure mycotoxins in human or animal tissue.	Few toxicological studies have been performed using inhalation as a route of exposure. Most of what is known about the physiological response to mycotoxin/ mold exposure is derived from animal studies using ingestion as a route of exposure; respiratory defense mechanisms differ from those present in the digestive system. The limited number of inhalational in vitro studies suggest that some molds produce hemolysins and other iron-scavenging substances that result in the destruction of RBCs. Also implicated in allergic responses and cytotoxicity.	See Table 2 for a summary of symptoms and diseases associated with indoor mold exposure. No effects are specific to either indoor molds or particular toxigenic species of mold. Makes establishing associations with indoor mold exposure more difficult. Three categories of effects: 1) Infection (only applicable to susceptible populations (e.g. immunosuppressed people) 2)Sensory Irritation 3)Allergy 4) Immune effects (e.g. inflammatory response, immunosuppression) Suspician of toxins produced by Stahybptrys chartarum as a possible cause of infant pulmonary hemorrhage have existed since the early 1990s. Only recently has this mold bees isolated from the lung of an infant suffering from this condition (Eldemir O. et al. Pediatrics 1999;102:964-966).

Figure 2.Symptoms/conditions associated with indoor mold exposure (non-allergic & allergic reactions)

Respiratory Effects

Cough

Shortness of breath

Asthma/wheezing

Bronchitis

Chest Tightness

Infant pulmonary hemorrhagae/ hemosiderosis

Ear, Nose & Throat

Sneezing

Sinus congestion/sinusitis

Sore throat

Eye

Irritation

Itchy watery eyes

Skin

Rash

Flushing