Exposure to field vs. storage wheat dust: different consequences on respiratory symptoms and immune response among...

The aim of this study was to understand the differential acute effects of two distinct wheat-related dusts, such as field or stored wheat dust handling, on workers' health and how those effects evolved at 6 month intervals.

Exposure, work-related symptoms, changes in lung function, and blood samples of 81 workers handling wheat and 61 controls were collected during the high exposure season and 6 months after. Specific IgG, IgE, and precipitins against 12 fungi isolated from wheat dust were titrated by enzyme-linked immunosorbent assay, dissociation-enhanced lanthanide fluorescence immunoassay, and electrosyneresis. The level of fungi was determined in the workers' environment. Levels of exhaled fraction of nitrogen monoxide (F_ENO) and total IgE were obtained. Exposure response associations were investigated by mixed logistic and linear regression models.

The recent exposure to field wheat dust was associated with a higher prevalence for five of six self-reported airway symptoms and with a lower F_ENO than those in the control population. Exposure to stored wheat dust was only associated with cough. No acute impact of exposure on respiratory function was observed. Exposure to field wheat dust led to workers' sensitization against the three field fungi Aureobasidum, Cryptococcus, and Phoma, although exposure to storage wheat dust was associated with tolerance. The level of Ig remained stable 6 months after exposure.

The clinical picture of workers exposed to field or storage wheat dust differed. The systematic characterization of the aerosol microbial profile may help to understand the reasons for those differences.