• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.2
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• pp.212-225
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• 1995

This study was performed in a diatomite factory located at Pohang City, Kyeongsangbuk-Do. The major objectives were to evaluate sampling and analytical methods of diatomaceous earth dust. Concentrations of total and respirable diatomaceous earth dust were measured. Size distribution of dust was analyzed by a personal cascade impactor and the particle size analyzer which is an application of multiple diffraction method. Also crystalline silica in respirable and total dust samples was analyzed quantitatively by X-ray diffraction and Fourie Transform Infrared Spectroscopy(FTIR). The results were as follows: The airborne total and respirable dust concentrations, particle size distribution, and cristalline silica(quartz) concentrations showed approximately a log-normal distribution. The means of totaldust concentrations at flour maufacturing, fire brick grinding and packaging processes exceeded the Korean and American Conference of Governmental Industrial Hygienists standards, $10mg/m^3$. The size distribution of diatomaceous earth dust was log-normal and identified as the rspirable particle mass and thoracic particle mass. The crystalline silica in respirable and total dust samples was identified to quartz and contained about 10 % in those samples. Finally, it is necessary to study the applicability of multiple diffraction for particle size distribution to compare the ACGIH's size selective sampling with other materials containing crystalline silica. Also, advanced quantitative study to X-ray diffraction and FTIR methods shoud be carried out 10 verify general and specific characteristics for respirable crystalline silica.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.3
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• pp.284-290
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• 2023

Objectives: Work environment assessments were conducted to investigate epidemiologically several cases of lung cancer and COPD (chronic obstructive pulmonary disease) among workers in domestic quarries. Methods: We visited three quarries in South Korea where an epidemiological investigation was requested and measured total dust, respirable dust, and crystalline silica on rock drilling workers (4 people) and rock chipping workers (13 people). Measurement and analysis were conducted according to NIOSH (National Institute for Occupational Safety & Health) method 0500, NIOSH method 0600 for respirable dust, and NIOSH method 7500 for crystalline silica. Results: Among rock drilling workers the AMs (arithmetic mean) of total dust concentrations, respirable dust concentrations, and crystalline silica concentrations were 3.462 mg/m³ (range: 0.764~6.085 mg/m³), 0.613 mg/m³ (range: 0.153~1.251 mg/m³), and 0.105 mg/m³ (range: 0.012~0.228 mg/m³), respectively. Among rock chipping workers, the AMs of total dust concentrations, respirable dust concentrations, and crystalline silica concentrations were 2.446 mg/m³ (range: 0.156~8.494 mg/m³), 0.488 mg/m³ (range: 0.028~1.536 mg/m³), and 0.099 mg/m³ (range: 0.004~0.274 mg/m³), respectively. Conclusions: Although it cannot be said that the dust concentrations were high for both rock drilling workers and rock chipping workers, the concentrations of crystalline silica were found to be high. If such work is performed for a long period of time, diseases such as lung cancer and COPD may occur, so the work environment needs to be improved.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.3
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• pp.291-297
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• 2023

Objectives: An epidemiological investigation was requested for a worker who developed COPD and IPF after long-term molding and firing at a domestic tile manufacturing site. We would like to share the results of the exposure assessment and the estimation of past work. Methods: The content of crystalline silica in four raw materials was analyzed, and the respirable fraction of crystalline silica and dust generated in the air from molding and firing workers and other processes were measured. The measurement and analysis method referred to the NIOSH method. Results: The crystalline silica content of the raw material was 24~47%. The concentration of crystalline silica in the molding and firing process workers and the surrounding area was at the level of the exposure standards set by the Ministry of Employment and Labor and ACGIH, and the respirable and total dust exposure levels were generally low. The crystalline silica concentration of the area samples measured to estimate past work was about twice as high as the exposure standard of the Ministry of Employment and Labor (0.05 mg/m3), and the exposure levels of respirable dust were also quite high at 0.903 and 1.332 mg/m3. Conclusions: It was confirmed that tile molding and firing workers are currently exposed to a fairly high level of crystalline silica, and a high level is also confirmed in area samples to estimate past work. In the past, it is judged that the level of exposure would have been much higher due to differences in production volume, working method, presence/absence of local ventilation facilities, and process layout. When working in such a working environment for a long time, respiratory diseases such as lung cancer, COPD, and IPF can occur.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.50-66
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• 1998

This study was conducted to estimate crystalline silica contents in airborne respirable dust from various manufacturing industries and to compare analytical performance of two methods of quantifying crystalline silica, X-ray diffraction(XRD) and Fourie transform infrared spectroscopy (FTIR). For this study, various manufacturing industries with a history of having pneumoconiosis cases and also known to generate dusts containing crystalline silica were investigated. These industries include: foundry, brick, potteries, concrete, and abrasive material, etc. Both personal and area respirable dust samples were collected using 10 mm, Dorr-Oliver nylon cyclone equipped with 37mm, $5{\mu}m$ pore size, polyvinylchloride (PVC) filters as collection media. In addition, total dust samples were collected side-by-side to the respirable samples. All samples were weighed before and after sampling and were pretreated according to the NIOSH sampling and analytical methods 0500, 7500, and 7602 for dust collection and quartz analysis. In addition, bulk samples were collected and analyzed by X-ray fluorescence (XRF) for minerals. In this article, only the results obtained from foundry are reported. The results from various other industries will be published in future articles. The respirable dust concentrations from personal samples by cyclone were $0.46-1.06mg/m^3$ and those from area samples were $0.34-0.73mg/m^3$. Dust concentrations of personal samples were significantly higher than those of area samples. The highest dust concentration was obtained from the personal samples of the finishing operation. Total dust concentration ranged $1.24-3.40mg/m^3$. The mean quartz contents estimated by FTIR and XRD in the personal respirable dust samples were 5.12% and 4.41%, respectively, without significant difference between them. For quartz analyses, the two techniques were highly correlated with $r^2$ ranged 0.803-0.920. But the results by FTIR were mostly higher than those by XRD. In addition, cristobalite was not detected by FTIR. Significant correlations between contents of crystalline silica and such minerals as $Al_2O_3$, CaO, $TiO_2$, and $K_2O$ suggest possible interferences from these minerals.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.99-111
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• 1999

The purpose of this study was to evaluate crystalline silica contents in airborne respirable dusts from various manufacturing industries and to compare analytical ability of two different methods of quantifying crystalline silica, X-ray diffraction(XRD) and Fourie transform infrared spectroscopy(FTIR). Various manufacturing industries with a history of having pneumoconiosis cases and also known to generate dusts containing crystalline silica were investigated. These industries include: ceramics, brick, concrete, and abrasive material etc. The personal respirable dust samples were collected using l0mm, Dorr-Oliver nylon cyclone equipped with 37mm, $5{\mu}m$ pore size. polyvinylchloride (PVC) filters as collection media. All samples were weighed before and after sampling and were pretreated according to the NIOSH sampling and analytical methods 7500, and 7602 for dust collection and quartz analysis. A total of 48 samples were collected from these industries. Initial analyses of these samples showed log-normal distributions for dust and quartz concentrations. Some results from ceramics and stone exceeded current Korean Occupational Exposure Limits. The average concentrations of personal respirable dust by cyclone were 0.43, 0.24, 0.26, 0.42, 0.53 and $0.29mg/m^3$ in ceramics, stone, concrete, glass, briquets, and others, respectively. A comparison of performance of two analytical methods for quantifying crystalline silica was performed using data from ceramics. The results showed that no significant difference was found between two methods for ceramics. The mean crystalline silica contents determined by XRD were 3.41 % of samples from briquets and 7.18 % from ceramics and were 2.58 % from concrete and 10.33 % from ceramics by FTIR. For crystalline silica analysis, two analytical techniques were highly correlated with $r^2=0.81$ from ceramics. Both cristobalite and tridymite were not detected by XRD and FTIR.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.1
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• pp.81-95
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• 1994

This study was performed in a diatomite factory where silicosis had been found at October, 1993. The major objectives were to evaluate worker exposure to diatomaceous earth and to present engineering control methods for workplace management. Total and respirable dust of diatomaceous earth were measured. Size distribution of dust was analyzed by applying the multiple diffraction method. Also crystalline silica in respirable dust samples was analyzed qualitatively by X-ray diffraction. The suitable Local Exhaust Ventilation systems for that factory were recommended. The results were as follows. The airborne total and respirable dust concentrations by exposure groups showed approximate normal distribution. The means of total dust exposures at flour maufacturing, fire brick grinding and packaging, ceramic raws packaging processes exceeded Korean and ACGIH standards, $10mg/m^3$. The means of total and respirable dust concentrations to high exposure groups were 6.8 and 3.9 times higher than those of low expousre groups, respectively. The size distribution of diatomaceous earth dust was lognormal with a median diameter of $7.07{\mu}m$(range, $0.10-60.0{\mu}m$) and with a geometric standard deviation of 1.43. The crystalline silica in respirable dust samples was identified to quartz and cristobalite and/or tridymite. Above results suggest that engineering controls and periodic environmental and medical surveillances will be important for preventing silicosis in the diatomite factory.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.398-422
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• 2017

Objectives: The major aim of this study is to construct the database of retrospective exposure assessment for crystalline silica through reviews of literatures in South Korea. Methods: Airborne concentrations of crystalline silica were collected using an academic information search engine, Research Information Service System(RISS), operated by the Korea Education & Research Information Service(KERIS). The key words used for the literature search were 'silica', 'crystalline silica', 'cristobalite', 'quartz' and 'tridymite'. A total number of 18 published documents with the information of crystalline silica level in air or bulk samples were selected and used to estimate retrospective exposures to crystalline silica. Weighted arithmetic mean(WAM) calculated across studies was summarized by industry type. Industries were classified according to Korea Standard Industrial Classification(KSIC) using information provided in the literature. Results: A total of 2,131 individual air sampling data measured from 1987 to 2012 were compiled. Compiled individual measurement data consisted of 827 respirable crystalline silica (RCS), 31 total crystalline silica(TCS), 24 crystalline silica(CS), 778 respirable dust(RD) and 471 total dust(TD). Most of RCS measurements(68.9%) were collected from 'cast of metals(KSIC 243)'. Comparing industry types, 'mining coal and lignite(KISC 051)' showed the highest WAM concentration of RCS, $0.14mg/m^3$, followed by $0.11mg/m^3$ of 'manufacture of other non-metallic mineral products(KSIC 239)', $0.108mg/m^3$ of 'manufacture of ceramic ware(KSIC 232)', $0.098mg/m^3$ of 'heavy construction(KSIC 412)' and $0.062mg/m^3$ of 'cast of metals(KSIC 243)'. In terms of crystalline silica contents in airborne dust, 'manufacture of other non-metallic mineral products(KSIC 239)' showed the highest value of 7.3%(wt/wt), followed by 6.8% of 'manufacture of ceramic ware(KSIC 232)', 5.8% of 'mining of iron ores(KSIC 061)', 4.9% of 'cast of metals(KSIC 243)' and 4.5% of 'heavy construction(KSIC 412)'. WAM concentrations of RCS had no consistent trends over time from 1994 ($0.26mg/m^3$) to 2012 ($0.12mg/m^3$). Conclusion: The data set related RCS exposure level by industries can be used to determine not only the possibility of retrospective exposure to RCS, but also to evaluate the level of quantitative retrospective exposure to RCS.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.168-179
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• 1994

In some ceramic industries, worker exposure to dust, crystalline free silica and lead were determined and evaluated. The conclusions are as follows. 1. Crystalline silica in bulk samples was 10.5 % in sanitary ware industry, 9.4 % in tile industry, and 2.1 % in ceramic insulator industry respectively. The free silica content of air filter sample was 8.03 % in table ware industry, 5.59 % in sanitary ware industry, and 1.32 % in ceramic insulator industry. Because silica content in ceramic dust is relatively high, it is should be considered silica as important factor in evaluating for ceramic industry. 2. The silica contents in dust from tile, sanitary ware and table ware industries are above 5%, it should be classified as "Type" 2 dust. 3. The airborne concentration of respirable crystalline silica was $27.9{\mu}g/m^3$ in a sanitary ware factory and $5.8{\mu}g/m^3$ in a ceramic insualtor factory. Three of ten samples sampled the above factories were exceeded the occupational exposure levels, $100{\mu}g/m^3$. 4. Geometric mean(GM) of total dust in 11 factories was $1.00mg/m^3$ and GM of respirable dust concentration in 5 factories was $0.33mg/m^3$. Sanitary ware industry had the highest concentration of total dust, $1.62mg/m^3$ and of respirable dust, $0.88mg/m^3$. 5. Average lead concentration in air was $0.05mg/m^3$ in glazing process of 2 factories manufacturing table ware. Five of ten sample(50%) were exceeded $0.05mg/m^3$. Therefore lead exposure in pottery industry should be considered as important problem.

• Safety and Health at Work
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• v.15 no.1
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• pp.96-101
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• 2024

Background: Silicosis among workers who fabricate engineered stone products in micro or small-sized enterprises (MSEs) was reported from several countries. Workplace exposure data of these workers at high risk of exposure to respirable crystalline silica (RCS) dust are limited. Methods: We surveyed workers performing cutting, shaping and polishing tasks at 6 engineered stone fabricating MSEs in Sydney, Australia prior to regulatory intervention. Personal exposure to airborne RCS dust in 34 workers was measured, work practices were observed using a checklist and worker demography recorded. Results: Personal respirable dust measurements showed exposures above the Australian workplace exposure standard (WES) of 0.1 mg/m³ TWA-8 hours for RCS in 85% of workers who performed dry tasks and amongst 71% using water-fed tools. Dust exposure controls were inadequate with ineffective ventilation and inappropriate respiratory protection. All 34 workers sampled were identified as overseas-born migrants, mostly from three linguistic groups. Conclusions: Workplace exposure data from this survey showed that workers in engineered stone fabricating MSEs were exposed to RCS dust levels which may be associated with a high risk of developing silicosis. The survey findings were useful to inform a comprehensive regulatory intervention program involving diverse hazard communication tools and enforcing improved exposure controls. We conclude that modest occupational hygiene surveys in MSEs, with attention to workers' demographic factors can influence the effectiveness of intervention programs. Occupational health practitioners should address these potential determinants of hazardous exposures in their workplace surveys to prevent illness such as silicosis in vulnerable workers.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.3
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• pp.286-292
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• 2016

Objectives: This study aimed to evaluate the effects of chronical exposure to high-level dusts on cellular immune function. Methods: The subjects were 110 male workers, among whom 60 were chronically exposed to high-level dusts in mica, limestone and iron mines. The remaining 50 were office workers. Ambient total, respirable dust and crystalline silica in the workplace were sampled using personal air samplers and analyzed according to NIOSH method 0500. Serum levels of hydrogen peroxide, lipid peroxide and superoxide misutase activity were measured using absorption chromatography. The subpopulations of CD4+, CD8+, natural killer cells (CD16+) and CD3+ T-lymphocytes were examined by two-color staining using monoclonal antibodies. Results: The concentration of hydrogen peroxide was significantly higher in exposed workers and superoxide dismutase activity was significantly higher in control workers. No significant difference in numbers of T-lymphocyte subpopulations were observed between exposed and control workers. A significant correlation in exposed workers was observed among total dusts, respirable dusts and crystalline silica. Hydrogen peroxide was significantly correlated with total dust (r=0.720, p<0.01), respirable dust (r=0.770, p<0.01) and crystalline silica (r=0.678, p<0.01). Concentration of hydrogen peroxide showed a significantly negative correlation with numbers of CD8+ cells (r=-0.274, p<0.01), CD3+ cells (r=-0.222, p<0.01) and natural killer cells (r=-0.556, p<0.01). Conclusions: These results suggest that chronical exposure to high-level dust affects cellular immune function and effects might mediate through reactive oxygen species and inflammatory response.