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Marcin Cyprowski, Agata Stobnicka, Rafał Górny, Małgorzata Gołofit-Szymczak, Anna Ławniczek-Wałczyk
Centralny Instytut Ochrony Pracy – Państwowy Instytut Badawczy

Abstract
The aim of the research was to identify aerosols of bacterial origin, including aerobic and anaerobic bacteria, peptidoglycans and endotoxins in working rooms of waste management facility, which included sorting and composting of municipal waste. Four sampling points were located in the plant: in the pre-sorting cab, in sorting hall at conveyor belts, in the composting bunkers hall, as well as in the front of entrance gate, as a sample of external background. Air samples for the presence of bacteria were collected using a 6-stage Andersen impactor, wherein two types of microbial media were loaded: TSA agar with defibrinated sheep blood for aerobic bacteria and Schaedler's agar for anaerobic bacteria. Air samples for the presence of endotoxins and peptidoglycans were carried out using 8-stage cascade impactor, wherein the glass fiber filters were provided. Biochemical API tests were used for a detailed identification of bacteria. Determination of peptidoglycans was carried out using the SLP test (Silkworm Larvae Plasma) and endotoxin - LAL assay (Limulus Amebocyte Lysate). The results of the quantitative analysis of bioaerosols at the three tested working rooms showed the following geometric mean (GM) concentrations: aerobic bacteria – 4348 cfu/m3 (geometric standard deviation, GSD = 1.14); anaerobic bacteria – 19914 cfu/m3 (GSD = 3.65); endotoxins – 173.6 ng/m3 (GSD = 2.39); peptidoglycans – 1446.6 ng/m3 (GSD = 1.21). Comparative analysis revealed statistically significant differences (p < 0.01) between the concentrations of aerobic bacteria in the working rooms and the external background – 551 cfu/m3. Anaerobic bacteria were the dominant group and accounted for 82% of all identified microorganisms. A total of 22 species of bacteria, belonging to 13 genera was identified in waste management facility. The greatest taxonomic diversity was observed in the sorting area (21 species), composting – 15, while in the background samples – 13 species. Among the identified species, six (Actinomyces israelii, A. meyeri, A. naeslundii, Clostridium perfrin-gens, Proteus vulgaris, and Streptomyces spp. can be treated as potentially harmful to waste workers, as they were classified into the second risk group by the ordinance of Minister of Health from 2005. Analysis of size distributions of bacteria showed that they occurred mostly in the form of single cells with an aerodynamic diameter in the range of 1.1-2.1 µm, and in the range of 4.7-7.0 µm, where the process of aggregation of bacterial cells with organic dust particles takes place. In the case of endotoxins and peptidoglycans we found a gradual increase in the concentrations of particles with aerodynamic diameters in the range of 3.3-11.0 µm. On the basis of the study it can be stated that the working rooms in waste management facility were heavily contaminated with aerosols of bacterial origin. Examination provided the pioneer results for anaerobic bacteria, which were the dominant group. Bacteria that can pose a health risk to exposed workers were also found in the air. The analysis of particle size distribution suggests that the bioaerosols observed in these rooms can accumulate in the middle and upper respiratory tract of employees, causing irritation of the nose and throat.

Słowa kluczowe
zakład gospodarki odpadami, bakterie, peptydoglikany, endotoksyny, rozkłady ziarnowe

Aerosols of Bacterial Origin in Working Rooms of Waste Management Facility

Key words 
waste management facility, airborne bacteria, peptidoglycans, endotoxins, size distribution

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