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Crystalline Silica (crystalline + silica)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Metal and non-metal miners' exposure to crystalline silica, 1998,2002

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 7 2006
James L. Weeks ScD
Abstract Background Crystalline silica is well known to cause silicosis and other diseases. Exposure is common in the mining industry and consequently, the US Mine Safety and Health Administration (MSHA) evaluates miners exposure to silica to determine compliance with its exposure limit. Methods MSHA exposure measurements were obtained for the 5-year period from 1998 to 2002 and average exposure was calculated classified by occupation and by mine. Evaluation criteria were whether average values exceeded MSHA's permissible exposure limit or the limit recommended by the National Institute for Occupational Safety and Health (NIOSH), whether there was a risk of exposure to freshly fractured silica, and whether there was a risk of a high rate of exposure to silica. Results Miners in certain jobs are exposed to silica above permissible and recommended exposure limits. Some miners may also be exposed at a high rate or to freshly fractured silica. Conclusions Known dust control methods should be implemented and regular medical surveillance should be provided. Am. J. Ind. Med. 49:523,534, 2006. © 2006 Wiley-Liss, Inc. [source]

Occupational exposure to crystalline silica and risk of systemic lupus erythematosus: A population-based, case,control study in the Southeastern United States

ARTHRITIS & RHEUMATISM, Issue 7 2002
Christine G. Parks
Objective Crystalline silica may act as an immune adjuvant to increase inflammation and antibody production, and findings of occupational cohort studies suggest that silica exposure may be a risk factor for systemic lupus erythematosus (SLE). We undertook this population-based study to examine the association between occupational silica exposure and SLE in the southeastern US. Methods SLE patients (n = 265; diagnosed between January 1, 1995 and July 31, 1999) were recruited from 4 university rheumatology practices and 30 community-based rheumatologists in 60 contiguous counties. Controls (n = 355), frequency-matched to patients by age, sex, and state of residence, were randomly selected from driver's license registries. The mean age of the patients at diagnosis was 39 years; 91% were women and 60% were African American. Detailed occupational and farming histories were collected by in-person interviews. Silica exposure was determined through blinded assessment of job histories by 3 industrial hygienists, and potential medium- or high-level exposures were confirmed through followup telephone interviews. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression. Results More patients (19%) than controls (8%) had a history of medium- or high-level silica exposure from farming or trades. We observed an association between silica and SLE (medium exposure OR 2.1 [95% CI 1.1,4.0], high exposure OR 4.6 [95% CI 1.4,15.4]) that was seen in separate analyses by sex, race, and at different levels of education. Conclusion These results suggest that crystalline silica exposure may promote the development of SLE in some individuals. Additional research is recommended in other populations, using study designs that minimize potential selection bias and maximize the quality of exposure assessment. [source]

Exposure to respirable dust and crystalline silica in bricklaying education at Dutch vocational training centers

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2010
Daan Huizer MSc
Abstract Background Construction workers are educated at vocational training centers before they begin their working lives. Future bricklayers and their instructors are exposed to respirable dust and possibly to hazardous respirable crystalline silica from trial mortar. Methods Thirty-six personal air samples were collected at six training centers to estimate exposure to respirable dust for both students and teachers. A selection of 22 samples was analyzed for crystalline silica. Results Average respirable dust exposures ranged from 0.59,mg/m3 for teachers to 1.45,mg/m3 for students performing recycling and cleaning tasks. In 45% of the analyzed samples, respirable crystalline silica was detected. Exposure to silica remained below the Dutch OEL (75,µg/m3). Exposure was significantly less for teachers than for students. This effect was found in both types of vocational training centers present in the Netherlands. Dry sweeping, as performed at all locations in this study, contributed considerably to the exposure to respirable dust. A first step in reducing exposure to dust and silica at training centers would therefore be to avoid dry sweeping. The presence of a dust extraction system, although not optimally designed, also significantly lowered exposure. Conclusions To assess a construction worker's lifetime exposure to respirable dust and crystalline silica, the vocational training period should also be taken into account. Several epidemiological studies have shown that time since first exposure can be an important risk factor for chronic health effects. Am. J. Ind. Med. 53: 628,634, 2010. © 2010 Wiley-Liss, Inc. [source]

Metal and non-metal miners' exposure to crystalline silica, 1998,2002

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 7 2006
James L. Weeks ScD
Abstract Background Crystalline silica is well known to cause silicosis and other diseases. Exposure is common in the mining industry and consequently, the US Mine Safety and Health Administration (MSHA) evaluates miners exposure to silica to determine compliance with its exposure limit. Methods MSHA exposure measurements were obtained for the 5-year period from 1998 to 2002 and average exposure was calculated classified by occupation and by mine. Evaluation criteria were whether average values exceeded MSHA's permissible exposure limit or the limit recommended by the National Institute for Occupational Safety and Health (NIOSH), whether there was a risk of exposure to freshly fractured silica, and whether there was a risk of a high rate of exposure to silica. Results Miners in certain jobs are exposed to silica above permissible and recommended exposure limits. Some miners may also be exposed at a high rate or to freshly fractured silica. Conclusions Known dust control methods should be implemented and regular medical surveillance should be provided. Am. J. Ind. Med. 49:523,534, 2006. © 2006 Wiley-Liss, Inc. [source]

One agent, many diseases: Exposure-response data and comparative risks of different outcomes following silica exposure,

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2005
Kyle Steenland
Abstract Background Evidence in recent years indicates that silica causes lung cancer, and probably renal disease, in addition to its well-known relationship to silicosis. There is also suggestive evidence that silica can cause arthritis and other auto-immune diseases. Silica has, therefore, joined a handful of other toxic exposures such as tobacco smoke, dioxin, and asbestos which cause multiple serious diseases. Methods The available exposure-response data for silica and silicosis, lung cancer, and renal disease are reviewed. We compare the corresponding excess risks (or absolute risks in the case of silicosis) of death or disease incidence by age 75 for these three diseases, subsequent to a lifetime (45 years) of exposure to silica at current US standard (0.1 mg/m3 respirable crystalline silica). Results The absolute risk of silicosis, as defined by small opacities greater than or equal to ILO classification 1/1 on an X-ray, ranges from 47% to 77% in three cohort studies with adequate follow-up after employment. The absolute risk of death from silicosis is estimated at 1.9% (0.8%,2.9%), based on a pooled analysis of six cohort studies. The excess risk of lung cancer death, assuming US male background rates, is 1.7% (0.2%,3.6%), based on a pooled analysis of ten cohort studies. The excess risk of end-stage renal disease (assuming male background rates) is 5.1% (2.2%,7.3%), based on a single cohort. The excess risk of death from renal disease is estimated to be 1.8% (0.8%,9.7%), based on a pooled analysis of three cohorts. Conclusions Keeping in mind that the usual OSHA acceptable excess risk of serious disease or death for workers is 0.1%, it is clear that the current standard is far from sufficiently protective of workers' health. Perhaps surprisingly, kidney disease emerges as perhaps a higher risk than either mortality from silicosis or lung cancer, although the data are based on fewer studies. Am. J. Ind. Med. 48:16,23, 2005. © 2005 Wiley-Liss, Inc. [source]

Respiratory effects of exposure to low levels of concrete dust containing crystalline silica

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2001
E. Meijer MD
Abstract Background Dusts containing crystalline silica are generated in mining, construction, glass, granite and concrete production industries. The association between exposure to low levels of concrete dust containing crystalline silica and reduction in lung function, was evaluated in a cross-sectional study. Methods The study was carried out among 144 concrete workers, from two factories, with exposure assessment of respirable dust and silica by personal samplers. Results of respiratory questionnaires and standardized measurements of lung function were compared with the results in a control population. Multiple linear regression analysis was used in selecting factors that predict (age and standing height standardized residual) lung function. Results The average concentration of respirable dust in both factories was 0.8 mg/m3 and 0.06 mg/m3 for respirable silica. The average silica content of the dust was 9%. The average cumulative dust exposure was 7.0 mg/m3 year and cumulative silica exposure was 0.6 mg/m3 year. Significant associations between exposure to concrete dust and a small lung function (FEV1/FVC ratio, MMEF) loss were found, independent of smoking habits and of a history of allergy. Conclusions Our results indicate that, concrete workers with chronic obstructive pulmonary symptoms and/or work-related lower respiratory symptoms are at risk of having a reduction in lung function (FEV&1/FVC ratio) outside the 5th percentile of the external reference population, and therefore, of mild chronic obstructive pulmonary disease, at respirable concrete dust levels below 1 mg/m3 with a respirable crystalline silica content of 10% (TWA, 8 hr). Am. J. Ind. Med. 40:133,140, 2001. © 2001 Wiley-Liss, Inc. [source]

Occupational exposure to crystalline silica and risk of systemic lupus erythematosus: A population-based, case,control study in the Southeastern United States

ARTHRITIS & RHEUMATISM, Issue 7 2002
Christine G. Parks
Objective Crystalline silica may act as an immune adjuvant to increase inflammation and antibody production, and findings of occupational cohort studies suggest that silica exposure may be a risk factor for systemic lupus erythematosus (SLE). We undertook this population-based study to examine the association between occupational silica exposure and SLE in the southeastern US. Methods SLE patients (n = 265; diagnosed between January 1, 1995 and July 31, 1999) were recruited from 4 university rheumatology practices and 30 community-based rheumatologists in 60 contiguous counties. Controls (n = 355), frequency-matched to patients by age, sex, and state of residence, were randomly selected from driver's license registries. The mean age of the patients at diagnosis was 39 years; 91% were women and 60% were African American. Detailed occupational and farming histories were collected by in-person interviews. Silica exposure was determined through blinded assessment of job histories by 3 industrial hygienists, and potential medium- or high-level exposures were confirmed through followup telephone interviews. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression. Results More patients (19%) than controls (8%) had a history of medium- or high-level silica exposure from farming or trades. We observed an association between silica and SLE (medium exposure OR 2.1 [95% CI 1.1,4.0], high exposure OR 4.6 [95% CI 1.4,15.4]) that was seen in separate analyses by sex, race, and at different levels of education. Conclusion These results suggest that crystalline silica exposure may promote the development of SLE in some individuals. Additional research is recommended in other populations, using study designs that minimize potential selection bias and maximize the quality of exposure assessment. [source]