Dust at Various Workplaces—Microbiological and Toxicological Threats

Abstract

The aim of the present study was to evaluate the relation between the chemical (analysis of elements and pH) and microbiological composition (culture and metagenomics analysis) of the dust at various workplaces (cement plant, composting plant, poultry farm, and cultivated area) and the cytotoxicity effect on the human adenocarcinoma lung epithelial adherent cell line A-549 (MTT assay test). Analysis of the Particulate Matter (PM) fraction showed that the dust concentration in cultivated areas exceeded the OELs. For the remaining workplaces examined, the dust concentration was lower than OELs limits. The number of microorganisms in the dust samples was 3.8 × 102–1.6 × 108 CFU/g bacteria and 1.5 × 102–6.5 × 106 CFU/g fungi. The highest number of microorganisms was noted for dust from cultivated areas (total number of bacteria, actinomycetes, P. fluorescens) and composting plants (xerophilic fungi and staphylococci), while the least number of microorganisms was observed for dust from cement plants. Many types of potentially pathogenic microorganisms have been identified, including bacteria, such as Bacillus, Actinomyces, Corynebacterium, Prevotella, Clostridium, and Rickettsia, and fungi, such as Alternaria, Cladosporium, Penicillium, and Aspergillus. The most cytotoxic to the human lung cell line A-549 was dust from cultivated areas (IC50 = 3.8 mg/mL after 72 h). The cytotoxicity of the tested dust samples depends on the PM concentration, the number of microorganisms, including potentially pathogenic genera, and the exposure time.

Microbial Growth on Dust-Loaded Filtering Materials Used for the Protection of Respiratory Tract as a Factor Affecting Filtration Efficiency

“…The high carbon to nitrogen ratio (C:N = 98.64) in dust from the composting plant promoted growth compared to dust from the cement plant, which had a low ratio (C:N ≈ 10). Gutarowska et al 2018 found different levels of microbial contamination in sedimented dust samples depending on the workplace—high for samples of cereal dust from a composting plant, lower for dust from a poultry farm and the lowest from a cement plant [ 7 ]. The highest number and variety of microorganisms was found in dust from composting plant and in cereal dust, while it was lowest in the case of a cement plant.…”

“…Dust B, with low microbial contamination (2.10 × 10 3 ± 1.77 × 10 2 CFU/g) and low carbon to nitrogen ratio (C:N = 10.71), was collected from the clinker transporting conveyor hall at cement plant (Chełm, Lublin providence, Poland). Detailed microbiological, chemical, and toxicological characterization of the studied dust types has been published in [ 7 ]. Prior to testing, collected dust samples (3 of each type) were subsequently sterilized for 15 min at 115 °C and dried for 24 h at 70 °C under reduced pressure of 100 mbar in drying chamber (VD 53, Binder, Germany).…”

“…However, the composition and cytotoxicity of dust in each of these places are different. Previous studies have shown that settled dust from composting plants contain significantly more microorganisms compared to cement plants, moreover their species diversity is significantly greater [ 7 ].…”

Survival of Microorganisms on Filtering Respiratory Protective Devices Used at Agricultural Facilities

“…Two types of dust were deposited onto filtering nonwovens: Organic dust from a composting plant (Łódź, Poland) collected at a refuse homogenization hall, and inorganic dust from a cement plant (Chełm, Poland) collected from a clinker conveyer belt. Detailed chemical, microbiological, granulometric and toxicological characteristics were presented in an earlier publication [36]. The research showed that at workplaces in composting and cement plants, the dominant PM fraction had an aerodynamic diameter below 1 μm, accounting for 87.3% and 80.8% of the total dust concentration.…”

“…The cement plant dust was characterised by a low carbon to nitrogen ratio (C:N about 10), and the composting dust by a high ratio of carbon to nitrogen (C:N = 98.64). Dust from cement plant was alkaline, dust from composting plant were slightly acidic [36]. Filtering nonwoven samples of 79 cm 2 were prepared according to methods described by Majchrzycka et al [26].…”