SESSION TYPE: Occupational/ Environmental Lung Disease
PRESENTED ON: Tuesday, October 23, 2012 at 04:30 PM - 05:45 PM
PURPOSE: Domestic exposure to fungi comprises a risk of non-allergic as well as allergic airways inflammation. Measurements of the exposure are thus important for diagnostic and prevention purposes. The active agents in fungi comprise β-glucan, chitin, and mannan. These agents retain their activity also in fragments of fungal cell walls. Previous studies have demonstrated that such fragments may comprise up to 50% of the total fungal cell biomass in airborne samples. This study was undertaken to determine the proportion of airborne, fungal cell fragments in homes and relate it to the presence of bacterial endotoxin.
METHODS: Airborne samples were collected in 15 homes using a NIOSH 2-stage cyclone sampler, collecting airborne particles in three size fractions: < 1.0 μm, 1.0 - 1.8 μm, and > 1.8 μm. Fungal cell biomass in the different fractions was determined by measuring NAHA. Endotoxin was measured using the Limulus amebocyte lysate method.
RESULTS: The average activities of NAHA and levels of endotoxin in all samples are reported in Table 1. Table 1. Average values of NAHA (U/m3) and endotoxin (EU/m3) in different particle sizes. Mean/SEM. Table 1. Average values of NAHA (U) and endotoxin (EU) in different particle sizes. Mean/SEM. Particle size μm total >1.8 1.0-1.8 < 1.0 NAHA 21.1/3.6 15.1/3.2 1.1/0.4 4.9/1.4 Endotoxin 7.2/2.0 5.4/1.5 0.4/0.2 1.4/0.5 The activity of NAHA in the particle size <1.0 μm ranged from 0 to 62.5% of the total activity (mean 22.7%, SEM 5.3) and that of endotoxin from 0.4 to 96.4 % (mean 22.6%, SEM 8.3). There was a significant correlation between NAHA and endotoxin in the total particle fraction (p = 0.011), and progressively lower in the other fractions (> 1.8 μm p = 0.016, 1.8-1.0 μm p = 0.037, and <1.0 μm NS).
CONCLUSIONS: The results demonstrate that fungal fragments may comprise a substantial part of the airborne exposure to fungal cell mass in homes. This could explain why poor relationships between symptoms and fungi, measured with conventional techniques such as spore counting, have been found in some previous studies. Endotoxin was also present in the small particle aerosol and related to the activity of NAHA. The results suggest that sampling techniques that include the fungal fragments are suitable for exposure determinations and risk assessments of fungal and endotoxin exposure.
CLINICAL IMPLICATIONS: Exposure assessment of fungal exposure for patients with respiraory problems should use sampling methods which include fungal fragments.
DISCLOSURE: The following authors have nothing to disclose: Ragnar Rylander, Tiina Reponen, Atin Adhikari
No Product/Research Disclosure InformationBioFact Env Health Res Center, Lerum, Sweden