Concentration of bioaerosols in composting plants using different quantification methods.

BACKGROUND: Bioaerosols (organic dusts) containing viable and non-viable microorganisms and their metabolic products can lead to adverse health effects in exposed workers. Standard quantification methods of airborne microorganisms are mainly based on cultivation, which often underestimates the microbial burden. The aim of the study was to determine the microbial load in German composting plants with different, mainly cultivation-independent, methods. Second purpose was to evaluate which working areas are associated with higher or lower bioaerosol concentrations. METHODS: A total of 124 inhalable dust samples were collected at different workplaces in 31 composting plants. Besides the determination of inhalable dust, particles, and total cell numbers, antigen quantification for moulds (Aspergillus fumigatus, Aspergillus versicolor, Penicillium chrysogenum, and Cladosporium spp.) and mites was performed. Concentrations of ß-glucans as well as endotoxin and pyrogenic activities were also measured. The number of colony forming units (cfu) was determined by cultivation of moulds and actinomycetes in 36 additional dust samples. RESULTS: With the exception of particle numbers, concentrations of all determined parameters showed significant correlations (P < 0.0001; r Spearman: 0.40-0.80), indicating a close association between these exposure markers. Colony numbers of mesophilic moulds and actinomycetes correlated also significantly with data of cultivation-independent methods. Exposure levels showed generally large variations. However, all parameters were measured highest in dusty working areas like next to the shredder and during processing with the exception of Cladosporium antigens that were found in the highest concentrations in the delivery area. The lowest concentrations of dust, particles, antigens, and pyrogenic activity were determined in wheel loader cabins (WLCs), which were equipped with an air filtration system. CONCLUSION: It was possible to assess the microbial load of air in composting plants with different quantification methods. Since allergic and toxic reactions may be also caused by nonliving microorganisms, cultivation-independent methods may provide additional information about bioaerosol composition. In general, air filtration reduced the bioaerosol exposure shown in WLCs. Due to the fact that the mechanical processing of compost material, e.g. by shredding or sieving is associated with the generation of high bioaerosol concentrations, there is still a need of improved risk assessment and state-of-the-art protective measures in composting plants.

Physical influences on seafarers are different during their voyage episodes of port stay, river passage and sea passage: A maritime field study.

INTRODUCTION: During a sea voyage, crew members of vessels are permanently exposed to physical stress caused by noise, vibration and heat. This study aims to describe the extent of the physical influences on board container ships and the resulting stress. METHODS: Up to four scientific investigators accompanied six sea voyages on container ships under German management. Workplace and person-related measurements for noise, vibration and climatic parameters were carried out on the vessels during the three different voyage episodes (port stay, river passage and sea passage). RESULTS: The interviewed seafarers reported, in decreasing order, the level of psychological stress due to vibration (80.6%), noise (71.8%) and, much less, heat (45.7%) in the workplace. In terms of workplace-related physical measurements, the highest noise levels were found in the engine room (104 dB (A)), in the workshop (81 dB (A)) and on deck (77 dB (A)), irrespective of the voyage episode. Some noise measurements in the recreational area revealed levels above the threshold. All measured 180 vibration values were below the relevant threshold limits-with the highest values in the engine room (62 mm/s2), followed by the workshop (37 mm/s2) and the engine control room (34 mm/s2). In terms of thermal comfort, none of the measured climatic parameters differed significantly between the voyage episodes. According to the person-related physical measurements, the noise exposure was particularly pronounced among the engine room personnel with an average noise level of 96 dB (A) (often during cleaning, painting and repair work). In contrast, the deck crew and nautical officers were respectively exposed to an average level of 83 dB (A) and 77 dB (A) at work. DISCUSSION: A relevant stress level due to physical loads was detectable in the present study. As ship crews are exposed to the physical influences on board for 7 days a week over several months, further research is recommended to assess the long-term health effects for seafarers.