Grain dust - a health risk for farmers

Department of Plant and Environmental Sciences, UMB.

On thursday, august 10, defended Anne Straunfors Halsteinsen her Doctoral Thesis ”Molecular and agricultural determinants of mycotoxin and microbial exposure in grain farming”

Foto: Erling Fløistad

She gave first a public lecture with the title: ”The genus Fusarium: Their biology and diseases in plants and animals”

SUMMARY, Anne Straumfors Halstensen

This thesis is based on a study of grain farmers’ exposure to possibly health impairing microbial components in grain dust and associations with meteorological data and grain cultivation practices. Special attention was made to find surrogates for mycotoxin exposure measurements.

Grain dust collected by personal sampling during threshing and grain storage work contained generally high levels of fungal spores, hyphae, actinomycetes, bacteria, endotoxin and glucans (Paper I). Grain-derived glucan appeared to represent a considerable part of the glucan exposure. This suggested that plant-derived glucans should be included in glucan specific health effect assessments, and that glucans are not suitable as fungal markers in agricultural environments.

Because mycotoxin analysis demands larger dust samples than obtained by personal sampling, settled grain dust was collected both for this purpose (Paper II-IV) and for fungal identification by cultivation (Paper II and IV). Ochratoxin A and the trichothecenes HT-2, T-2 and DON were detected in most grain dust samples (Paper II-IV). Fusarium spp. in settled dust were difficult to cultivate, but a novel semi-quantitative PCR assay revealed that most samples contained DNA of toxigenic Fusarium spp., which correlated with the HT-2, T-2 and DON levels. This suggested that Fusarium-DNA could be used as surrogate measures for mycotoxins in settled dust (Paper IV).

TaqMan real-time PCR was used to quantify F. langsethiae, F. avenaceum and all potentially trichothecene-producing Fusarium spp. (tri5) in airborne dust (Paper V), which may provide more precise estimates for assessing health risks related to mycotoxins. PCR is independent of cultivability, and detects all DNA containing fungal structures, including hyphae. Weak correlations between specific DNA levels in settled and airborne dust indicated that settled dust measurements would give poor exposure estimates, thus emphasizing the importance of personal sampling (Paper V).

Meteorological conditions known to promote fungal growth and mycotoxin production were associated with HT-2, DON, ochratoxin A and Penicillium spp. in settled dust (Paper II-III), and with increased exposure to endotoxin, glucans and hyphae during threshing (Paper I), whereas none of the production practices had particular influence. However, storage work, mould damage observation in the field, and work with barley was related to increased dustiness and elevated microbial exposure (Paper I-II)
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Halsteinsen, A.S. 2006. ”Molecular and agricultural determinants of mycotoxin and microbial exposure in grain farming.” Norwegian University of Life Sciences, Ås, Norway. Doctor of philosophy (PhD) thesis 13, ISBN: 82-575-0709-1, ISSN: 1503-1667


Updated: 26.03.07
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