Graduation Year

2005

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Public Health

Major Professor

Yehia Y. Hammad, Sc.D.

Committee Member

Noreen D. Poor, Ph.D.

Committee Member

Ann C. Debaldo, Ph.D.

Committee Member

Diane Te Strake, Ph.D.

Keywords

Mold, Mould, Carbon dioxide, Antimony trioxide, Flame retardant

Abstract

Fungal contamination of buildings poses numerous challenges to researchers, building owners and occupants. Public health agencies promote prevention and remediation of mold and water damage, but lack sensitive methods to detect hidden mold growth and a complete understanding of the biological mechanisms that make occupying moldy buildings a hazard. The wide spread use of the fire retardant antimony trioxide (Sb2O3) on building materials and furnishings makes it inevitable that mold growth on treated materials will occur in some buildings with water damage. Several authors have speculation that microbial growth on materials treated with antimony trioxide could mobilize antimony through a volatile intermediate, trimethylstibine.

The purpose of this study was to determine if fungal growth on a commonly used building material that contains antimony trioxide, fiberglass ductboard, results in the mobilization and release of antimony compounds. Additionally, CO2 generation rates were determined during fungal growth on fiberglass ductboard and gypsum wallboard.

Results demonstrated a significant reduction of antimony concentration in fiberglass ductboard after fungal growth had occurred. Antimony emission rates and resulting concentrations of antimony oxide aerosols were estimated using an indoor mass balance mathematical model. Concentrations of CO2 were also modeled within a wall cavity and static HVAC ducts to determine if fungal growth could elevate CO2 levels above ambient concentrations.

Although volatile phase antimony was not detected in chamber experiments, probably due to rapid oxidation and high humidity, mobilization of antimony trioxide from fiberglass ductboard components was demonstrated in several experiments. Indoor Air modeling of a residence suggest that concentrations of antimony could, under worst case conditions, exceed the reference concentration (RfC) of antimony trioxide by 10 to 1,000 times. These results suggest that biomethylation and mobilization of antimony by mold growth on building materials could result in elevated occupant exposures to antimony compounds. Antimony is a known respiratory irritant that can be similar to arsenic in its toxicity.

Modeling results also suggest that elevated carbon dioxide concentrations due to fungal metabolic respiration are variable and dependent on environmental conditions. Measuring elevated carbon dioxide concentrations to detect hidden fungal growth was determined to not be a predictive assessment tool.

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