An Investigation into Techniques for Cleaning Mold-Contaminated Home Contents

Abstract

This study examined the efficacy of the following treatments to reduce selected fungal spore and mycotoxin levels on materials commonly found in home contents: (1) gamma irradiation at a 10–13 kiloGray exposure, (2) a detergent/bleach wash, and (3) a steam cleaning technique. A minimum of six replicates were performed per treatment. Paper, cloth, wood, and carpet were inoculated with either fungal spores (Stachybotrys chartarum, Aspergillus niger, Penicillium chrysogenum, or Chaetomium globosum) at 240,000 spores/2.54 cm² of material or with the mycotoxins roridin A, T-2, and verrucarin A at 10 μg per 2.54 cm²of material. Treatments were evaluated with an agar plating technique for fungal spores and a yeast toxicity culture assay for mycotoxins. Results showed that gamma irradiation inactivated fungal spores, but the treatment was not successful in inactivating mycotoxins. The washing technique completely inactivated or removed spores on all materials except for C. globosum, which was reduced on all items except paper (p < 0.05). Washing inactivated all mycotoxins on paper and cloth but not on carpet or untreated wood (p < 0.001). The steam cleaning treatment did not completely eliminate any fungal spores; however, it reduced P. chrysogenum numbers on all materials, C. globosum was reduced on wood and carpet, and S. chartarum was reduced on wood (p < 0.05). Steam cleaning was unsuccessful in inactivating any of the tested mycotoxins. These results show that the bleach/detergent washing technique was more effective overall in reducing spore and mycotoxin levels than gamma irradiation or steam cleaning. However, the other examined techniques were successful in varying degrees.

Keywords:

• contents
• fungi
• mycotoxin
• sick building syndrome
• sterilization

ACKNOWLEDGMENTS

Financial support was provided by Assured Indoor Air Quality Ltd., Dallas, Texas, and Texas Tech University Health Sciences Center (TTUHSC). Drs. Stephen Wilson and David Straus were supported by a Center of Excellence grant from TTUHSC; Dr. David Straus, Mr. Gary Fortenberry, Mr. Trevor Brasel, and Ms. Enusha Karunasena were supported by a grant from the Texas Higher Education Coordinating Board. The authors would also like to gratefully acknowledge the technical and material support from Mr. Mark LeGarda of Steris Isomedix Services, El Paso, Texas.