[Exposure assessment to harmful agents in workplaces in sewage plant workers]. / Ocena narazenia pracowników oczyszczalni scieków na czynniki szkodliwe wystepujace w miejscu pracy.

BACKGROUND: The purpose of the study was to evaluate exposure to biological and chemical agents in a sewage treatment plant. MATERIALS AND METHODS: Sampling was carried out in the summer and wintertime at the morning workshift. Ninety-nine sewage workers taking part in the study were divided into four occupational subgroups: mechanical treatment, biological treatment, sewage sludge treatment, and operation control workers. Exposure to: H2S, SO2, Pb, Cd, Cr3+, Cr6+, endotoxins, (1 --> 3)-beta-D glucans, and microorganisms was evaluated with special identification of Gram-negative rods. RESULTS: The concentrations of dust containing heavy metals and concentrations of gases from all stations did not exceed MAC values. Concentrations of endotoxins ranged from 0.08 to 223 ng/m3, and glucans from 0.00 to 163 ng/m3. The highest concentrations were found among sewage sludge treatment workers, in the summertime (geometric mean value = 37 ng/m3). In the winter, concentrations were almost ten times lower. Over sixty percent of all results exceeded the proposed reference value for airborne endotoxins (10 ng/m3). Concentrations of airborne bacteria in the sewage plant were at low level (10(2)( cfu/m3), except the sludge lagoon and sludge concentration building, where the results exceeded the proposed reference value for mesophilic bacteria (10(5) cfu/m3) "Environmental" bacteria (Pseudomonas, Burkholderia, Shewanella) predominated in the samples. There were also found enterobacteria genus (Enterococcus, family Enterobacteriaceae)--good indicators of hygienic cleanliness of the air. CONCLUSIONS: The study proved that the exposure varied and depended on the stage of sewage treatment. The sewage sludge treatment process was characterized by the highest emission of bioaerosols. All microorganisms found in the sewage plant belong to the second occupational risk group, under the ordinance of the Ministry of Health.

Occupational exposure to organic dust associated with municipal waste collection and management.

The aim of the study was to assess the occupational exposure of workers employed in the municipal waste collection and management industry. Air samples were collected in the workers' breathing zone; two samples were collected parallely. The assessment concerned exposure to organic dust, endotoxins, bacteria and fungi. The questionnaire data showed that workers found themselves in good or very good health. They also regarded noise, dustiness, odor, physical effort and changeable atmospheric conditions as the most strenuous factors. The highest dust concentrations were observed on the sites of waste collection (mean, 7.7 mg/m3) and composting (mean, 4.6 mg/m3). Samples collected on the composting site contained the largest amount of endotoxins (mean concentration, 76 ng/m3). This was followed by sorting facility (61 ng/m3) and waste collection area (36 ng/n3). Gram-negative rods (primarily intestinal) were found in all samples collected at workposts, which justified the adoption of the air concentrations of endotoxins as a criterion for assessing their hygienic conditions. Taking MAC for total suspended dust (4.0 mg/m3) and the concentration of 10 ng/m3 for endotoxin as the criteria for the exposure evaluation, it must be considered that waste collectors and composting site workers are working in poor hygienic conditions. Workers employed at the most hazardous workposts did not use personal protective equipment (glasses, antirespirators), thus infringing a fundamental condition for limiting health hazards (Directive 2000/54/EC).