Cross-shift study of exposure–response relationships between bioaerosol exposure and respiratory effects in the Norwegian grain and animal feed production industry

Abstract

ObjectiveWe have studied cross-shift respiratory responses of several individual bioaerosol components of the dust in the grain and feed industry in Norway.MethodsCross-shift changes in lung function and nasal congestion, as well as in respiratory and systemic symptoms of 56 exposed workers and 36 referents, were recorded on the same day as full-shift exposure to the inhalable aerosol fraction was assessed. Exposure–response associations were investigated by regression analysis.ResultsThe workers were exposed on average to 1.0 mg/m3 of grain dust, 440 EU/m3 of endotoxin, 6 µg/m3 of β-1,3-glucans, 17×104/m3 of bacteria and 4×104/m3 of fungal spores during work. The exposure was associated with higher prevalence of self-reported eye and airway symptoms, which were related to the individual microbial components in a complex manner. Fatigue and nose symptoms were strongest associated with fungal spores, cough with or without phlegm was associated with grain dust and fungal spores equally strong and wheeze/tight chest/dyspnoea was strongest associated with grain dust. Bioaerosol exposure did not lead to cross-shift lung function decline, but several microbial components had influence on nose congestion.ConclusionsExposure to fungal spores and dust showed stronger associations with respiratory symptoms and fatigue than endotoxin exposure. The associations with dust suggest that there are other components in dust than the ones studied that induce these effects.

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

“…Decreases in FVC among grain handlers have been significantly correlated with increasing grain dust exposure (doPico et al 1983). Cross-shift lung function changes have also been observed among grain workers (doPico et al 1983) and wheat harvest workers (Viet et al 2001), but not in the most recent studies (Straumfors et al 2016). Our results are consistent with those published by Straumfors et al (2016) and support a normal decline in lung function at a 6-month interval in grain workers and cattle raisers.…”

“…Cross-shift lung function changes have also been observed among grain workers (doPico et al 1983) and wheat harvest workers (Viet et al 2001), but not in the most recent studies (Straumfors et al 2016). Our results are consistent with those published by Straumfors et al (2016) and support a normal decline in lung function at a 6-month interval in grain workers and cattle raisers. Taken together, those results suggest that decreasing the level of exposure was not strong enough to affect lung function, but was still sufficient to induce acute symptoms during wheat harvesting.…”

“…Indeed, asthma-like syndrome was mostly described in grain elevator operators, although COPD has been reported in multiple cattle raisers (May et al 2012). Different effects on inhalation of distinct grain dust components have been suggested previously in healthy grain worker populations (Straumfors et al 2016). In this recent study, the self-reported airway symptoms were related to the individual microbial components in a complex manner.…”

“…Endotoxin exposure was the first etiological factor proposed to explain the biological effects caused by grain dust exposure (Jagielo et al 1996). Since then, respiratory symptoms have been shown to have a stronger association with the air's fungal spore content than with endotoxin (Straumfors et al 2016). Fungi act as irritants, toxins, aeroallergens, or pathogens that cause infection depending on underlying disease, species, and form (Wiszniewska et al 2013;Vacher et al 2015;Kuhn and Ghannoum 2003).…”

Pneumoproteins and markers of inflammation and platelet activation in the blood of grain dust exposed workers

“…An inconsistency in exposure-response relationships has been observed between studies that may be due to differential effects of individual grain dust components and differences between studies in grain dust composition , Halstensen et al 2013. Although endotoxin has been proposed as a target for measurements of occupational health hazard related to grain dust exposure (Health Council of the Netherlands 2011), fungal spore exposure has been shown to be stronger associated with respiratory effects and fatigue than endotoxin (Straumfors et al 2016). A possible reason for the diverging relationships in epidemiological studies is the healthy worker selection.…”