Over the past decade, there has been growing concern regarding the role of toxigenic fungi in damp indoor environments; however, there is still a lack of field investigations on exposure to mycotoxins. The goal of our pilot study was to quantify the proportion of toxigenic Aspergillus versicolor isolates in native carpet dust from damp dwellings with mould problems and to determine whether sterigmatocystin can be detected in this matrix. Carpet dust samples (n = 11) contained from <2.5 × 101 to 3.6 × 105 (median, 3.1 × 104A. versicolor CFU/g of dust, and the median proportion of A. versicolor from total culturable fungi was 18%. Based on thin-layer chromatography detection of sterigmatocystin, 49 of 50 A. versicolor isolates (98%) were found to be toxigenic in vitro. By using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry, sterigmatocystin could be detected in low concentrations (2 to 4 ng/g of dust) in 2 of 11 native carpet dust samples. From this preliminary study, we conclude that most strains of A. versicolor isolated from carpet dust are able to produce sterigmatocystin in vitro and that sterigmatocystin may occasionally occur in carpet dust from damp indoor environments. Further research and systematic field investigation are needed to confirm our results and to provide an understanding of the health implications of mycotoxins in indoor environments.

Several epidemiological studies indicate that children and adults living in damp indoor environments are more likely to suffer from respiratory as well as general symptoms (e.g., tiredness, headaches, nausea, and vomiting), and exposure to fungi has been suggested as being an important contributory factor. The underlying mechanisms, however, are not well known.

Case reports and studies of agricultural workers indicate that certain health effects occur as a result of inhalation of moulds, which are due at least in part to mycotoxins. To date, however, relatively few studies have examined exposure to mycotoxins in indoor environments. The current scientific literature on this topic focuses mainly on trichothecene mycotoxins produced by Stachybotrys chartarum. In addition, Aspergillus versicolor is presumed to be of concern, because it belongs to the most frequently occurring species found in damp indoor environments and is known to be the major producer of the hepatotoxic and carcinogenic mycotoxin sterigmatocystin. In a study of water-damaged building materials, analyses of wallpaper and fibreglass wallpaper naturally contaminated with A. versicolor revealed sterigmatocystin and 5-methoxysterigmatocystin. Tuomi and coworkers found sterigmatocystin in 24% of bulk samples of moldy interior finishes from Finnish buildings with moisture problems, ranging from 0.2 to 1,000 ng per g (fresh weight) of sample.

Review the full study published on Applied and Environmental Microbiology here.