Efficacy of sodium hypochlorite disinfectant on the viability and allergenic properties of household mold

Abstract

Rationale Many fungi colonize indoor environments and produce allergenic proteins that cause adverse health symptoms in sensitive individuals. The effect of sodium hypochlorite (2.4% NaOCl) disinfectant on fungal growth and the presence of allergenic properties was evaluated. Methods Environmental and laboratory isolates of common indoor mold contaminants ( Penicillium, Cladosporium, Mucor, Rhizopus, Stachybotrys, Alternaria, Aspergillus, Helminthosporium, and Trichophyton) were grown to sporulation, purified, dried on sterile ceramic porous and non-porous carriers, and treated with 2.4% NaOCl for up to 10 min. Volunteer's showers were monitored, for 2 weeks to determine the rate of mold regrowth following disinfectant treatment. ELISA tests measured the ability of NaOCl to reduce the allergenic properties of Aspergillus fumigatus following 30 sec, 1 min, and 5 min exposures. Results 2.4% NaOCl reduced total mold counts in home showers by >4 logs after 5 min exposures. In controlled laboratory studies, home mold isolates were reduced by >5 logs following 5 min exposures with 2.4% NaOCl. Test organisms were not culturable in 10 out of 10 trials after 5 and 10 min contact times in non-porous and porous ceramic carriers, respectively. NaOCl treatment reduced A. fumigatus allergen levels by >90% in as little as 30 seconds. Conclusions Low concentrations (2.4%) of NaOCl, common to household disinfectants, are effective at reducing mold from indoor surfaces, to undetectable levels, in both real-time and seeded laboratory studies. In addition, NaOCl effectively fragments the proteins responsible for the allergenic properties of indoor mold.