Bestimmung der Konzentration Biologischer Arbeitsstoffe in der Luft am Arbeitsplatz : Erster Ringversuch Schimmelpilze

Biological agents (moulds, bacteria etc.) can be found at many workplaces, e.g. in the waste industry or where cooling lubricants are used. Standardised measuring methods are indispensable for ensuring a harmonised evaluation of microbiological workplace exposure. The first interlaboratory trial was intended to gather information on the efficiency of the Method for determining mould/yeast concentrations in workplace air. Coordinated by the Berufsgenossenschaftliches Institut fur Arbeitssicherheit - BIA, the trial was carried out by the project group 4 Workplace assessment (former task force Measuring methods, measuring strategy) of the Committee for Biological Agents at Work. The method includes sampling with separation on a membrane filter and determination after culturing on nutrient media. A total of eight institutions participated in the interlaboratory trial. Samples were taken in a composting plant, both outdoors near the entrance of the administration building (Direct method) and indoors in the sorting cabin, where organic waste is prepared for composting (Indirect method). The sampling method made its proof under the given sampling conditions. If outliers (highest and lowest individual value) are excluded, mould concentration values determined in one filter series vary by the factor ∼ 2 as far as the Indirect method is concerned. The relative standard deviation comes to 30 to 41% for DG-18-Agar and 45 to 48% for MEA. Variance of values is not only due to laboratory conditions, but also to heterogeneous spore distribution at the sampling place. Compared to other approaches (e.g. impaction), the investigated sampling system offers several advantages: determination of the inhalable fraction, personal sampling, quantitative determination of high mould concentrations with long sampling times and variable preparation of loaded filters (direct, indirect). On account of the results obtained in exhaustive measuring series and in the described interlaboratory trial, a revised version of the measuring protocol was elaborated. Further interlaboratory trials (moulds, bacteria) are planned.