Assessment of Fungal Growth on Sodium Polyborate-Treated Cellulose Insulation

Cellulose insulation has rapidly gained a large market share among general contractors and homeowners. Recent interest regarding health effects of high concentrations of fungi within indoor environments (building-related illnesses or sick building syndrome) has promoted concern about susceptibility of building materials, including wood products (in general) and cellulose insulation (specifically), to fungal attack. This study reports an assessment of fungal growth on cellulose insulation made from recycled paper and treated with varying concentrations of sodium polyborate within half-scale wall units exposed to variable and high ambient temperatures and relative humidities throughout the summer. Boron-treated and untreated (control) cellulose insulation within the wall units were challenged with a suspension containing high concentrations of spores of five fungal species commonly found in indoor environments. Our results suggest that cellulose insulation treated with sodium polyborate (a) precludes the growth of the five common fungal species; (b) harbors fewer fungal species before and after being challenged with the fungal spore suspension; and (c) is likely having a cytotoxic or sporocidal effect on many, if not all, fungal species. These results suggest that cellulose insulation treated with sodium polyborate, when properly applied and installed, precludes fungal growth for at least 124 days at high temperatures and relative humidities.

Keywords:

• boron
• cellulose insulation
• fungi
• indoor air quality
• mold
• sick building syndrome

ACKNOWLEDGMENTS

Undergraduates Melvin Omodon, Niba Nchuto, Christina Gray, and Lindsay Ricketts of Truman State University ably assisted in the processing of some samples. Thanks are due to Bill Kuntz and the Truman State University farm for allowing us to conduct our summer-long study in the Agricultural Science Laboratory building. Jimmy Story from Missouri Enterprise introduced the opportunity to conduct research on cellulose insulation.

Portions of this study were financially supported by a consortium of cellulose insulation manufacturers headed by InCide Technologies, Inc.