Mold growth on gypsum wallboard--a summary of three techniques.

Author:Menetrez, M.Y.
Position::Report
 
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Introduction

In the past 20 years, researchers have increasingly recognized that an important factor in the health of people in indoor environments is the dampness of the buildings in which they live and work (Dearborn, Iwona, Sorenson, & Miller, 1999; Vesper & Vesper, 2002; Vesper et al., 2000). Furthermore, it is now understood that the principal biological contaminants responsible for the health problems in such buildings are fungi rather than bacteria or viruses (Dearborn, Iwona, Sorenson, & Miller, 1999; Scheel, 2001; Vesper & Vesper, 2002; Vesper et al., 2000). Although traditionally fungi in this context have been viewed as allergens (and in unusual circumstances, pathogens), data have accumulated to show that the adverse health effects resulting from inhalation of fungal spores are due to multiple factors (Sudakin, 2000). One factor associated with certain fungi is small molecular toxins (mycotoxins) produced by these fungi. Previously, mycotoxins were thought to be important in human and animal health because of their production by toxigenic fungi associated with food and feed. Mycotoxins tend to concentrate in fungal spores, however, and thus present a potential hazard to those inhaling airborne spores. Toxigenic spores strongly affect alveolar macrophage function and pose a threat to those exposed. Reports have indicated that Stachybotrys chartarum, Aspergillus versicolor, and several toxigenic species of Penicillium are potentially hazardous, especially when the air-handling systems have become heavily contaminated (Murtoniemi et al., 2001; Scheel, 2001; Sudakin, 2000; Vesper et al., 2000).

One of the toxigenic fungi found in wet buildings is S. chartarum, a fungus known to produce the very potent cytotoxic macrocyclic trichothenes along with a variety of immunosuppressants and endothelin-receptor-antagonist mycotoxins (Dearborn, Iwona, Sorenson, & Miller, 1999; Vesper & Vesper, 2002; Vesper et al., 2000). Infants have been admitted to Case Western University Hospital in Cleveland in very grave condition, expelling blood from their nose and mouth from pulmonary hemorrhage (PH) (Dearborn, Iwona, Sorenson, & Miller, 1999; Vesper & Vesper, 2002; Vesper et al., 2000). Forty-five cases of PH in young infants have occurred, 16 of whom have died. Most of these cases have occurred within 10 contiguous zip code areas in the eastern portion of the metropolitan area of Cleveland. In November and December 1994, the Centers for Disease Control and Prevention (CDC) led a case-control investigation on the first 10 cases. This investigation found an epidemiological association of PH in these infants with water-damaged homes containing toxic fungi, predominantly S. chartarum (Dearborn, Iwona, Sorenson, & Miller, 1999; Vesper & Vesper, 2002; Vesper et al., 2000). The importance of environmental tobacco smoke (ETS) exposure in conjunction with S. chartarum in producing PH has been discussed by Sudakin (2000). The importance of ETS as a multiplicative risk factor for toxic mold exposure and PH is unknown.

S. chartarum requires water-soaked cellulose to grow and has been found in homes where water damage had occurred from flooding, plumbing leaks, or roof leaks involving wood or paper products (e.g., insulation, gypsum wallboard [GWB], or ceiling tile). The spores of this fungus contain mycotoxins, which appear to be particularly toxic to the rapidly growing lungs of infants (Dearborn, Iwona, Sorenson, & Miller, 1999; Murtoniemi et al., 2001; Scheel, 2001; Sudakin, 2000; Vesper & Vesper, 2002; Vesper et al., 2000). Although not widely found, S. chartarum has been studied for the last 20 years. These studies have documented the following: (1) S. chartarum produces toxigenic spores that are potentially hazardous; (2) the prevalence of S. chartarum contamination in indoor environments is unknown; (3) currently no U.S. Environmental Protection Agency (U.S. EPA) regulations or guidelines exist for evaluating potential health risks of S. chartarum contamination and remediation; and (4) the exact environmental conditions necessary for the growth of S. chartarum have not been documented (Dearborn, Iwona, Sorenson, & Miller, 1999; Murtoniemi et al., 2001; Scheel, 2001; Sudakin, 2000; Vesper & Vesper, 2002; Vesper et al., 2000.)

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