Foreword: JEM Spotlight: Fungi, mycotoxins and microbial volatile organic compounds in mouldy interiors from water-damaged buildings

Hans P. van Egmond

Hans van Egmond is Head, Section of Natural Toxins and Nitroso Compounds, Laboratory for Food and Residue Analysis, at the National Institute for Public Health and the Environment in Bilthoven, the Netherlands. He holds a MSc. degree in Food Technology and his professional interests are primarily in the food safety area, and specifically deal with mycotoxins, phycotoxins and plant toxins. He is author and co-author of 190 research and review publications in the area of natural toxins, and he has (co-)edited several books in this field. His team is involved in activities with various international organizations and several interlaboratory research and networking projects, funded by the European Commission. These largely take place at the interface of analytical methodology, risk assessment and legislative requirements for natural toxins. Hans van Egmond serves on the Editorial Board of AOAC International and he is Editor-in-Chief of ‘World Mycotoxin Journal’.

Since the aflatoxins were discovered half a century ago, after the outbreak of Turkey X disease in England, mycotoxins (toxic fungal metabolites) and mycotoxicoses (diseases caused by mycotoxins) have become subjects of significant concern and intense investigations among researchers in various disciplines. Many articles and books on mycotoxins have been published and dozens of mycotoxin conferences and workshops have been held. Several international organizations became interested in mycotoxins, thematic interlaboratory research projects were initiated and professional networks created. Throughout these activities, and in the efforts to combat the problems caused by mycotoxins, consumption of mycotoxin-contaminated food was considered by far the most important route of human exposure. However, during the last decades it was recognised that other routes of human exposure to mycotoxins cannot be neglected. Research showed that fungi in indoor air may be associated with the health of exposed inhabitants, partly due to the formation of mycotoxins in mouldy interiors, particularly in connection with water-damaged buildings. Yet, in contrast to the subject of mycotoxins in food and animal feed, publications on this subject are relatively scarce.

The paper of Polizzi et al. (DOI: 10.1039/B906856B) is a comprehensive paper in the subject area of fungi and mycotoxins in indoor environments. At the same time, the study includes information about microbial volatile organic compounds (VOCs). The aims of the published study were to reveal the presence of fungi and mycotoxins in water-damaged buildings and to analyse microbial VOCs as possible indicators of fungal growth. For the study, 7 water-damaged buildings throughout Belgium were selected. In some of these, at least one of the inhabitants reported health problems, starting after mould growth. Samples were taken in mouldy interiors, by scraping off mycelium from surfaces. If this was not possible, mouldy wallpaper or silicone from window sealings were cut away, and mycelium was sampled by “stick-to-it” lift tape. Dust was also collected, as well as air samples. All samples were analysed for moulds and mycotoxins, and air samples were investigated to determine microbial VOCs.

For the determination of mycotoxins, the researchers applied the use of sophisticated analytical techniques, involving liquid chromatography-triple quadrupole mass spectroscopy, which allowed the multi-screening of targeted compounds. Generally recognized identification criteria (the presence of two selected fragment ions, relative retention time of the analyte and relative ion intensities) confirmed the presence of various mycotoxins in sampled air and, for some of these, also in dust, wall paper, mycelium and, incidentally, in silicone. Mainly sterigmatocystin, roquefortine C and chaetoglobosin A were found, but also roridin E, ochratoxin A, and the aflatoxins B₁ and B₂. In addition, liquid chromatography quadrupole time-of-flight mass spectrometry was used, which allowed the tentative identification of non-targeted compounds. This resulted in the annotation of a further 42 fungal metabolites, that may be present in mouldy interiors. The finding of aflatoxins B₁ and B₂ in air and dust samples appeared quite unexpected at first sight because, until recently, there have been no indications that these mycotoxins can be associated with buildings and indoor environments. However, this confirms other recent findings by Hintikka et al.¹ The aflatoxins B₁ and B₂ have been classified by the International Agency for Research on Cancer as human carcinogens, and therefore their presence is of potential concern. More than 100 microbial VOCs were found, but none of the compounds were definitely produced by the isolated fungi or could be held responsible for the mouldy odour. Thus, these research findings remained inconclusive.

In general, the fungal strains identified matched well with the mycotoxins detected. The concentrations of the various mycotoxins found were low, in the sub ng m⁻³ range for the air samples and mostly in the sub ng cm⁻² range for the other investigated materials. It is difficult to determine whether the amounts of toxins found are in any way sufficient to produce adverse symptoms in the inhabitants of the water-damaged buildings. Additionally, there was a large spread on the concentrations measured for different mycotoxins and also for different substrates containing the same mycotoxin. Currently there are no formal risk assessments on mycotoxins in indoor environments and there are no accepted guidelines on fungal spores or mycotoxins in indoor air. This is in contrast to the situation for mycotoxins in food and animal feed, where more than 100 countries now have (science-based) regulations and official limits for a number of mycotoxins, which can be used as benchmarks to determine the seriousness of mycotoxin contaminations. One issue of possible concern is the earlier finding that some mycotoxins can be 10 times more toxic through inhalation than by oral intake.² Besides, we do not yet know what the combined effects on human health are of different mycotoxins, which were found together in some samples in the reported study.

The article of Polizzi et al. (DOI: 10.1039/B906856B) is a welcome contribution to our knowledge and understanding of the potential problems, caused by fungi in indoor environments. However, as pointed out by the authors, more studies are needed to establish whether the exposure to (combinations of) indoor mycotoxins and other biologically active agents are indeed relevant to human health. Those who wish to read further about the subject area, may be interested to know that a new book: “Molds, Water and the Built Environment” edited by Olaf Adan and Robert A. Samson, will be published early 2010 by Wageningen Academic Publishers, the Netherlands.

References

1. E.-L. Hintikka, R. Holopainen, A. Asola, M. Jestoi, M. Peitzsch, S. Kalso, L. Larsson, K. Reijula and T. Tuomi, World Mycotoxin Journal, 2009, 2 DOI:10.3920/WMJ2009.1155 , in press.
2. D. A. Creasea, J. D. Thurman, L. J. Jones III, M. L. Nealley, C. G. York, R. W. Wannemacher Jr. and D. L. Bunner, Fundam. Appl. Toxicol., 1987, 8, 230.

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