Recent Trend of Fungal Contamination in Bathrooms

A comparison was made of fungal flora in bathrooms in 1997 and in 2007 to clarify the trend of fungal contamination and the causative factors. In 1997, Cladosporium and Exophiala were predominant on the walls and floors of bathrooms. In 2007, the fungal count on walls was lower than in 1997, and not only Cladosporium, but also Exophiala, Cladophialophora, Phoma, and Scolecobasidium were frequently observed. Cladosporium was found to be more common in bathrooms of the classic type with cement surfaces. In contrast, Exophiala, Phoma, Cladophialophora and Scolecobasidium were predominant in bathrooms of the modular type made of plastic boards, which have recently become more common than the classic type. Moreover, fungal contamination involving these four fungi, was often found on toys, soap dishes, and drain mouths made of plastic materials. These four fungi are known to use surfactant as nutrient, and surfactant may thus be more difficult to wash away from plastic than from tile and cement. The factors affecting the fungal flora on bathroom walls and floors were also compared. On both sampling occasions, more fungal contamination was detected in bathrooms located on lower floors or used by larger families than in those on upper floors or used by smaller families. Fungal contamination in bathrooms with dryer fans , which have recently become common, was about half of that in those without. Factors removing moisture from bathrooms were therefore thought to reduce fungal contamination. However, reducing fungal contamination is more difficult on floors than on walls, and no effective method has yet been found in spite of various improvements in materials and structure.