Mycotoxin Production on Water Damaged Building Materials

Due to the increased occurrence of flooding, biological by-products such as mycotoxins can cause serious health problems for homeowners. This study used two species of fungi, Aspergillus fumigatus and Stachybotrys chartarum, which have been found within homes after flooding events. Two distinct types of mycotoxins can be produced; gliotoxin by A. fumigatus and trichothecenes by S. chartarum. A preliminary study evaluated four wall materials separately, for mycotoxin production and validation of techniques. Based on these results, the experimental study built replicated interior walls of gypsum wallboard, fiberglass batt insulation, wood stud, and oriented strand board; placed the walls in mold chambers on concrete pavers; flooded and drained the walls; and exposed these walls to S. chartarum for 65 days. All four building materials showed some level of mycotoxin present on all collection days. Gypsum wallboard and fiberglass batt insulation had the highest levels of trichothecenes and levels increased over time. The wood stud and oriented strand board also contained mycotoxins, but levels did not change over time. DNA concentrations were significantly higher on the batt insulation compared to wood products. However, DNA concentrations did not directly correlate to mycotoxin levels. These results support the removal of the batt insulation and gypsum wallboard from a home if a flooding event should occur. The finding of the mycotoxin on the wood products requires further research to better understand the mycotoxin’s properties on wood in order to ensure the safety of homeowners

Mycotoxin Production on Water Damaged Building Materials

Due to the increased occurrence of flooding, biological by-products such as mycotoxins can cause serious health problems for homeowners. This study used two species of fungi, Aspergillus fumigatus and Stachybotrys chartarum, which have been found within homes after flooding events. Two distinct types of mycotoxins can be produced; gliotoxin by A. fumigatus and trichothecenes by S. chartarum. A preliminary study evaluated four wall materials separately, for mycotoxin production and validation of techniques. Based on these results, the experimental study built replicated interior walls of gypsum wallboard, fiberglass batt insulation, wood stud, and oriented strand board; placed the walls in mold chambers on concrete pavers; flooded and drained the walls; and exposed these walls to S. chartarum for 65 days. All four building materials showed some level of mycotoxin present on all collection days. Gypsum wallboard and fiberglass batt insulation had the highest levels of trichothecenes and levels increased over time. The wood stud and oriented strand board also contained mycotoxins, but levels did not change over time. DNA concentrations were significantly higher on the batt insulation compared to wood products. However, DNA concentrations did not directly correlate to mycotoxin levels. These results support the removal of the batt insulation and gypsum wallboard from a home if a flooding event should occur. The finding of the mycotoxin on the wood products requires further research to better understand the mycotoxin’s properties on wood in order to ensure the safety of homeowners

Fungal Communities on Flooded Building Materials

Flood waters will penetrate the wall cavities of a home and the wall materials then serve as a substrate for mold development. This study measured the effect of flooding and subsequent drying on the extent and type of mold on different residential wall materials. Wet and dry wall samples were analyzed by cloning and sequencing and twenty-one mold species were identified from above and below the water line. Real-time PCR quantitated selected species on fiberglass batt insulation, gypsum wallboard, wood stud, plywood panels, vinyl siding, and house wrap. The mold species found in the highest concentration were Aspergillus fumigatus, Paecilomyces variotii, Chaetomium globosum, and Stachybotrys chartarum. The batt insulation supported the highest concentration of mold, followed by the wood stud, sheathing and gypsum wallboard. The high level of Aspergillus fumigatus and Stachybotrys chartarum on the wall materials seven months after flooding is a cause for concern

Fungal Communities on Flooded Building Materials

Flood waters will penetrate the wall cavities of a home and the wall materials then serve as a substrate for mold development. This study measured the effect of flooding and subsequent drying on the extent and type of mold on different residential wall materials. Wet and dry wall samples were analyzed by cloning and sequencing and twenty-one mold species were identified from above and below the water line. Real-time PCR quantitated selected species on fiberglass batt insulation, gypsum wallboard, wood stud, plywood panels, vinyl siding, and house wrap. The mold species found in the highest concentration were Aspergillus fumigatus, Paecilomyces variotii, Chaetomium globosum, and Stachybotrys chartarum. The batt insulation supported the highest concentration of mold, followed by the wood stud, sheathing and gypsum wallboard. The high level of Aspergillus fumigatus and Stachybotrys chartarum on the wall materials seven months after flooding is a cause for concern

Fungal Populations in Air and Materials in a Flood Simulation Study

Air quality was measured in a building subjected to flooding conditions analogous to that which occurred during Hurricane Katrina. This building was flooded to a depth of 0.61 m above the floor with pond water and maintained at that level for 3 wk. After the floodwater was drained, the building remained closed for an additional 3 wk. Immediately on opening, air samples were obtained and analyzed for fungal spores. Dry and wet material components of the building wall were analyzed for the presence of mold fungi by both culture and molecular techniques. Additional air samples were taken after a 30-da drying period and then after remediation of the building. The air measurements demonstrated the presence of high concentrations of indoor mold spores when the building was initially entered. Aspergillus/Penicillium were the dominate air molds. Fiberglass batt insulation supported the greatest concentration of culturable fungi, compared with other wall materials, followed by the paper facings of gypsum board and plywood sheathing. The solid wood stud, vinyl siding, and house wrap all supported low concentrations of culturable mold. After drying, the spore air contamination diminished more than 10-fold and the species of fungi on the materials drastically changed. After remediation, the spores inside the structure nearly matched those outside with respect to type and concentration