Assessment of mould spore exposure and relations to symptoms in wood trimmers

Relationships between exposure to mould spores, IgG antibodies against moulds and respiratory and febrile symptoms were studied among wood trimmers. A new method for quantitative assessment of mould spore exposure by scanning electron microscopy was developed. This method was validated by comparison with other microscopical methods. The precision of mould counts was in accordance with expectations if aggregation of mould spores was taken into account. Specific IgG antibody levels, which are biomarkers of exposure, were correlated with exposure levels to spores from the corresponding mould species. Respiratory symptoms were correlated with factors associated with mould spore exposure, exposure measured in the working environment and specific IgG antibody levels to moulds. Antibodies to the most prevalent mould among those assessed by serology, R. microsporus , was the best indicator of retrospectively recorded symptoms, especially when the average antibody level in groups of sawmill workers working in the same working area was used. The results support the hypothesis that exposure to mould spores may cause respiratory symptoms in wood trimmers.