Environmental and occupational respiratory disordersThe medical effects of mold exposure
Section snippets
The relationship of molds to allergy and asthma
It is estimated that approximately 10% of the population have IgE antibodies to common inhalant molds.3 About half of these individuals (5% of the population) are predicted to have, at some time, allergic symptoms as a consequence of exposure to fungal allergens.4 Although indoor fungal allergen exposure occurs, outdoor exposure is generally more relevant in terms of sensitization and disease expression. The role of indoor fungi in the pathogenesis of allergic disease has been extensively
Allergic bronchopulmonary aspergillosis and sinusitis
Allergic bronchopulmonary aspergillosis (ABPA) is a well-recognized clinical entity affecting individuals with asthma or cystic fibrosis.21 A variety of fungi in addition to Aspergillus fumigatus can produce a similar clinical picture. The critical element in ABPA is an underlying anatomic change in the lung and not a specific mold exposure because at-risk individuals will have ongoing exposures caused by the ubiquitous nature of the fungi involved. Exposure to A fumigatus can occur both from
Hypersensitivity pneumonitis
HP, also referred to as extrinsic allergic alveolitis, is a disease that exists in acute, subacute, and chronic forms but with considerable overlap. It is an allergic disease in which the allergen is inhaled in the form of an organic dust of bacterial, fungal, vegetable, or avian origin. Both sensitization and the elicitation of the disease state generally require high-dose exposure, prolonged exposure, or both to the causative allergen. Many cases are, in fact, occupational because of this.
Infection
Superficial mold infections (eg, tinea cruris, onychomycosis, and thrush) are common in healthy individuals and result primarily from local changes in the cutaneous or mucosal barrier, resident microflora, or both.24, 25 These infections are not the result of environmental exposure, except occasionally as related to certain animal vectors. Indeed, molds of the Malassezia genus are resident on the vast majority of human subjects and only become evident as “tinea versicolor” during periods of
Ingestion
Ingestion of mycotoxins in large doses (generally on the order of a milligram or more per kilogram of body weight) from spoiled or contaminated foods can cause severe human illness.26 Toxicity from ingested mycotoxins is primarily a concern in animal husbandry, although human outbreaks do occur occasionally when starvation forces subjects to eat severely contaminated food. Specific adverse effects from a given toxin generally occur in a narrower and better-defined dose range than for
Irritant effects of mold exposure
The Occupational Health and Safety Administration defines an irritant as a material causing “a reversible inflammatory effect on living tissue by chemical action at the site of contact.” Irritant effects are dose related, and the effects are transient, disappearing when the exposure has decreased or ceased.
Molds produce a number of potentially irritating substances that can be divided into volatile organic compounds (VOCs) and particulates (eg, spores, hyphae fragments, and their components).
Immune dysfunction
The question has been raised as to whether mold or mycotoxin exposure can induce disorders of immune regulation. At this time, there is no credible evidence to suggest that environmental exposure to molds or their products leads to a state of clinically significant altered immunity expressed as either immunodeficiency or autoimmunity. The published literature in this regard is of particularly poor quality and should not be relied on as scientifically valid.33, 34 Individuals who have had
Measurement of IgE antibodies to mold proteins
Assessment for IgE antibodies to mold antigens has clearly been validated as a measure of potential allergic reactivity to mold. This assessment can be done through either in vivo or in vitro testing. The relative strengths of these different forms of testing have been reviewed recently.36, 37 In general, there is a weaker correlation between in vivo and in vitro testing for IgE antibodies to mold antigens than for other antigens, partly as a result of the heterogeneity of extractable mold
Remediation
Issues regarding remediation of mold are beyond the scope of this article. Indoor mold growth should be addressed. These matters are reviewed at length in the Institute of Medicine 2004 report “Damp indoor spaces and health.” For an overview, the reader can refer to the Occupational Health and Safety Administration document “A brief guide to mold in the workplace.”42 The true challenges of mold remediation are currently being addressed in the flood-ravaged areas struck by hurricane Katrina,
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