Journal of Health and Safety at Work

Introduction: Exposure to crystalline silica in the construction workers such as miners and diggers are widespread. Exposure to respirable silica (quartz) can results in silicosis. The goal of this study was to determine the contribution of each workers and component task to total dust and respirable quartz exposure in the tunnel of metro.

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Method and Materials: The assessment of crystalline silica and total dust was performed according to standard procedure ( NIOSH 7601).

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Results: Both total dust and quartz levels were high. The results of total dust in the digging process (37.63± 0.76 mg/m3) were higher than in the cement work ( 9.88 ± 0.80 mg/m3). The maximum 8 h time-weight average concentration for quartz was found among the digging workers (0.407± 0.006 mg/m3) , followed by the barbed workers (0.11 ± 0.008 mg/m3).

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Conclusion: It can be concluded that the total dust contains high amounts of crystalline silica and it is responsible for the occupational exposure to quartz in n construction workers. Thus, it is to be expected that the construction workers will suffer negative health effects due to exposure to the quartz dust.

Introduction: Exposure to respirable fraction of cement dust and its crystalline silica content is the most important occupational risk factor in cement industries requiring more evaluation and monitoring. This study aimed to assess exposure to crystalline silica and cement dust among workers of a cement industry in Saveh city, Iran.

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Material and Method: In this cross-sectional study, 62 samples of respirable dust were collected from breathing zone of the workers in different sections of factory. Determination of respirable fraction of cement dust concentrations carried out using gravimetric method according to the NIOSH method no. 0600. Visible absorption spectrophotometry was used according to the NIOSH method no. 7601 to determine crystalline silica content of respirable dust samples.

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Result: The highest exposure concentrations to respirable fraction of cement dust was observed in the Raw Mill and Cement Mill, and the lowest exposure in Administrative Department and Kiln the range of workers exposure in the production sites were 1.77 to 18.89 mg/m3. The range of workers exposure to the crystalline silica in the production sites was 0.011 to 0.104 mg/m3. The highest and lowest mean of exposures was observed in the raw Mill and cement mill respectively. Occupational exposure to the crystalline silica in 57% of site samples exceeded adjusted TLV recommended by NIOSH and Iranian of Occupational Health Technical Committee (0.05 mg/m3). The average of free SiO2 fraction in whole site samples was 1.17% varying from 0.49% in the cement Mill to 1.53% and 1.7% in crusher and Kiln sections, respectively

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Conclusion: Levels of exposure to cement respirable dust in all productive sections were significantly higher than the adjusted TLV. However, in administrative and control departments it was lower than the TLV level. Regarding crystalline silica, levels of exposure only in “Raw mill” and “kiln” were significantly higher than the adjusted TLV. Highest exposure concentrations to respirable fraction of cement dust recorded in Raw Mill and cement mill, and exposure to crystalline silica in raw Mill, Crusher and kiln, Therefore, preventive measures should primarily be targeted at these units.

Introduction: Occupational exposure to crystalline silica increases the risk of lung cancer and restrictive lung disease with extensive fibrosis. Silica dust is a major health hazard in foundry factories. The aim of this study was to determine core making workers’ exposure to respirable crystalline silica dust in a foundry factory.

Material and Method: This cross-sectional study was conducted in core-making unit of a foundry factory in 2015. Occupational exposure of 55 workers to respirable crystalline silica aerosols was evaluated by using the improved NIOSH7602 method in core-making unit. Risk assessments for silicosis and excess lifetime risk of mortality from lung cancer were done according to Manettej and Rice models, respectively. Data was analyzed with Spss19 software.

Result: The mean of respirable crystalline silica dust was 0.246 ± 0.351 (mg/m3). All  workers’ exposure to respirable crystalline silica was higher than recommended occupational exposure limits. Silicosis mortality risk and excess lifetime risk of mortality from lung cancer were estimated in the range of 6-63 and 65 per thousand people, respectively.

Conclusion: The mean of workers’ exposure to respirable crystalline silica was higher than recommended occupational exposure standards in core making unit. The risk assessment of silicosis mortality and excess lifetime risk of mortality from lung cancer were higher than acceptable levels of risk.

Introduction: Exposure to crystalline silica dust can seriously threaten health of workers engaged in processes such as casting, stone crushing, grinding, construction activities, insulator manufacturing, and glassblowing and sandblasting. The aim of this study was to assess occupational exposure to crystalline silica and to determine the risk of mortality from silicosis and lung cancer in an insulator manufacturer.

Material and Method: Air personal sampling was performed using 10 mm nylon cyclone and mixed cellulose ester (MCE) membrane filters (5 mm diameter, 0.8 μm pore size) for 60 male workers. Samples were prepared and analyzed according to the National Institute for Occupational Safety and Health (NIOSH) 7601 standard method. The risk assessment of mortality due to silicosis resulting from crystalline silica exposure was done by using model of Mannetje et al. for the period of 10 years. The mortality rate of lung cancer was determined using a linear regression model derived from the study Rice et al.  

Result: The highest and lowest exposure levels to silica were belonged to the packing unit (0.54±0.28 mg/m3) and the furnace (0.02±0.01 mg/m3), respectively. Crystalline silica concentrations for all samples were higher than Threshold Limit Values (0.025 mg/m3) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). According to Mannetje et al. model, the cumulative exposure of 25% workers was in the range 0 to 0.99 that it represents 1 death per 1,000 people. The risk of mortality due to lung cancer was obtained in the range of 7-94 persons per 1000 workers exposed to silica.

Conclusion: In general, the geometric and arithmetic mean of crystalline silica exposure was higher than threshold limit value for most of the subjects. For all workers of the insulator manufacturer, the risk of silicosis related mortality was higher than 1/1,000 (unacceptable level of risk). Predicting the lung cancer mortality from silica exposure indicated a high level of mortality risk among understudied workers.