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Published on: January 9, 2013
Fungal Fragments and Fungal Aerosol Composition in Sawmills
Komlavi Anani Afanou1, Wijnand Eduard1, Helle Birgit Laier Johnsen2
1Department of Chemical and Biological Work Environment, STAMI National Institute of Occupational Health, Oslo, Norway.
Abstract:
Assessment of exposure to fungi has commonly been limited to fungal spore measurements that have shown associations between fungi and development or exacerbation of different airway diseases. Because large numbers of submicronic fragments can be aerosolized from fungal cultures under laboratory conditions, it has been suggested that fungal exposure is more complex and higher than that commonly revealed by spore measurements. However, the assessment of fungal fragments in complex environmental matrix remain limited due to methodological challenges. With a recently developed immunolabeling method for field emission scanning electron microscope (FESEM), we could assess the complex composition of fungal aerosols present in personal thoracic samples collected from two Norwegian sawmills. We found that large fungal fragments (length >1 µm) dominated the fungal aerosols indicating that the traditional monitoring approach of spores severely underestimate fungal exposure. The composition of fungal aerosols comprised in average 9% submicronic fragments, 62% large fragments, and 29% spores. The average concentrations of large and submicronic fragments (0.2-1 µm) were 3 × 105 and 0.6 × 105 particles m-3, respectively, and correlated weakly with spores (1.4 × 105 particles m-3). The levels of fragments were 2.6 times higher than the average spore concentration that was close to the proposed hazardous level of 105 spores per m3. The season influenced significantly the fungal aerosol concentrations but not the composition. Furthermore, the ratio of spores in the heterogeneous fungal aerosol composition was significantly higher in saw departments as compared to sorting of green timber departments where the fungal fragments were most prevalent. Being the dominating particles of fungal aerosols in sawmills, fungal fragments should be included in exposure-response studies to elucidate their importance for health impairments. Likewise, the use of fungal aerosol composition in such studies should be considered.
Insights
Fungal fragments, not just spores, dominate airborne fungi in sawmills, suggesting current exposure assessments underestimate health risks. New methods reveal fragments are much higher than spores, highlighting their importance for occupational health studies.
Area of Science:
- Environmental Science
- Mycology
- Occupational Health
Background:
- Fungal exposure is linked to airway diseases, but traditional spore measurements may underestimate total fungal bioaerosols.
- Fungal fragments, especially submicronic ones, can be aerosolized and contribute significantly to exposure.
Purpose of the Study:
- To assess the complex composition of fungal aerosols in Norwegian sawmills using a novel immunolabeling method with field emission scanning electron microscopy (FESEM).
- To compare fungal fragment and spore concentrations and their contribution to overall fungal exposure in different sawmill departments.
Main Methods:
- Collection of personal thoracic samples from two Norwegian sawmills.
- Utilized a recently developed immunolabeling method for FESEM to analyze fungal aerosol composition.
- Quantified submicronic fragments, large fragments (>1 µm), and spores.
Main Results:
- Large fungal fragments constituted the majority (62%) of fungal aerosols, significantly underestimating exposure by spore-only measurements.
- Average concentrations of large and submicronic fragments were substantially higher (2.6 times) than spore concentrations.
- Fungal aerosol composition varied by department, with fragments prevalent in saw departments and spores higher in green timber sorting areas.
Conclusions:
- Traditional spore monitoring severely underestimates fungal exposure in occupational settings like sawmills.
- Fungal fragments are the dominant airborne fungal particles and should be included in future exposure-response and health impairment studies.
- The novel FESEM immunolabeling method provides a more comprehensive assessment of fungal aerosols.
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