Occurrence of Toxigenic Aspergillus versicolor Isolates and Sterigmatocystin in Carpet Dust from Damp Indoor Environments

Steffen Engelhart,^1* Annette Loock,¹ Dirk Skutlarek,¹ Helmut Sagunski,² Annette Lommel,² Harald Färber,¹ and Martin Exner¹

Institute of Hygiene and Public Health, University of Bonn, Bonn,¹ Behörde für Arbeit, Gesundheit und Soziales, Amt für Gesundheit, Freie und Hansestadt, Hamburg, Germany²

Received 17 October 2001/ Accepted 13 May 2002

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 mold problems and to determine whether sterigmatocystin can be detected in this matrix. Carpet dust samples (n = 11) contained from <2.5 x 10¹ to 3.6 x 10⁵ (median, 3.1 x 10⁴) A. 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.

* Corresponding author. Mailing address: Institute of Hygiene and Public Health, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany. Phone: 49-228-287-5520. Fax: 49-228-287-5645. E-mail: steffen.engelhart@ukb.uni-bonn.de.