Co-occurrence of toxic bacterial and fungal secondary metabolites in moisture-damaged indoor environments

• Published in: Indoor air Vol. 21; no. 5; pp. 368 - 375
• Main Authors: Täubel, M., Sulyok, M., Vishwanath, V., Bloom, E., Turunen, M., Järvi, K., Kauhanen, E., Krska, R., Hyvärinen, A., Larsson, L., Nevalainen, A.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2011; Hindawi Limited
• Subjects: Air Pollution, Indoor - analysis; Bacteria; Bacteria - growth & development; Bacteria - isolation & purification; Bacteria - metabolism; Bacterial metabolites; Bacterial Toxins - isolation & purification; Bacterial Toxins - metabolism; Basic Medicine; Biocompatibility; Building materials; Construction Materials - analysis; Construction Materials - microbiology; Dust; Dust - analysis; Environmental Microbiology; Environmental Monitoring; Fungi - growth & development; Fungi - isolation & purification; Fungi - metabolism; House dust; Indoor; Indoor air quality; Indoor environments; Mass spectrometry; Medical and Health Sciences; Medicin och hälsovetenskap; Medicinska och farmaceutiska grundvetenskaper; Metabolites; Microbiology in the medical area; Microorganisms; Mikrobiologi inom det medicinska området; Mycotoxins; Mycotoxins - isolation & purification; Mycotoxins - metabolism; Risk assessment; Secondary metabolites; Streptomyces; Tandem Mass Spectrometry - methods; Toxic; Airborne dusts; Building materials; Buildings; Moisture; House dust; Streptomyces; In-buildings; Toxic materials; Indoor environment; Buildings materials; Co-occurrence; Bacterial metabolite; Dust; Secondary metabolites; Metabolites; Microbial metabolites; Risk assessment; Bacteria (microorganisms); Bacteria; Biomolecules; Mass spectrometry
• ISSN: 0905-6947; 1600-0668; 1600-0668
• DOI: 10.1111/j.1600-0668.2011.00721.x

Toxic microbial secondary metabolites have been proposed to be related to adverse health effects observed in moisture‐damaged buildings. Initial steps in assessing the actual risk include the characterization of the exposure. In our study, we applied a multi‐analyte tandem mass spectrometry‐based methodology on sample materials of severely moisture‐damaged homes, aiming to qualitatively and quantitatively describe the variety of microbial metabolites occurring in building materials and different dust sample types. From 69 indoor samples, all were positive for at least one of the 186 analytes targeted and as many as 33 different microbial metabolites were found. For the first time, the presence of toxic bacterial metabolites and their co‐occurrence with mycotoxins were shown for indoor samples. The bacterial compounds monactin, nonactin, staurosporin and valinomycin were exclusively detected in building materials from moist structures, while chloramphenicol was particularly prevalent in house dusts, including settled airborne dust. These bacterial metabolites are highly bioactive compounds produced by Streptomyces spp., a group of microbes that is considered a moisture damage indicator in indoor environments. We show that toxic bacterial metabolites need to be considered as being part of very complex and diverse microbial exposures in ‘moldy’ buildings. Practical Implications Bacterial toxins co‐occur with mycotoxins in moisture‐damaged indoor environments. These compounds are measurable also in settled airborne dust, indicating that inhalation exposure takes place. In attempts to characterize exposures to microbial metabolites not only mycotoxins but also bacterial metabolites have to be targeted by the analytical methods applied. We recommend including analysis of samples of outdoor air in the course of future indoor assessments, in an effort to better understand the outdoor contribution to the indoor presence of microbial toxins. There is a need for a sound risk assessment concerning the exposure to indoor microbial toxins at concentrations detectable in moisture‐damaged indoor environments.