granite and Silicosis

Silica is one of the most common occupational exposures worldwide. In 1997 the International Agency for Research on Cancer (IARC) classified inhaled crystalline silica as a human carcinogen (group 1), but acknowledged limitations in the epidemiologic data, including inconsistencies across studies and the lack of extensive exposure-response data. We have conducted a pooled exposure-response analysis of 10 silica-exposed cohorts to investigate lung cancer.. The pooled cohort included 65,980 workers (44,160 miners, 21,820 nominees), and 1,072 lung cancer deaths (663 miners, 409 nonminers). Follow-up has been extended for five of these cohorts beyond published data. Quantitative exposure estimates by job and calendar time were adopted, modified, or developed to permit common analyses by respirable silica (mg/m3) across cohorts.. The log of cumulative exposure, with a 15-year lag, was a strong predictor of lung cancer (p = 0.0001), with consistency across studies (test for heterogeneity, p = 0.34). Results for the log of cumulative exposure were consistent between underground mines and other facilities. Categorical analyses by quintile of cumulative exposure resulted in a monotonic trend with odds ratios of 1.0. 1.0, 1.3, 1.5, 1.6. Analyses using a spline curve also showed a monotonic increase in risk with increasing exposure. The estimated excess lifetime risk (through age 75) of lung cancer for a worker exposed from age 20 to 65 at 0.1 mg/m3 respirable crystalline silica (the permissible level in many countries) was 1.1-1.7%, above background risks of 3-6%.. Our results support the decision by the IARC to classify inhaled silica in occupational settings as a carcinogen, and suggest that the current exposure limits in many countries may be inadequate. These data represent the first quantitative exposure-response analysis and risk assessment for silica using data from multiple studies.

Topics: Air Pollutants, Occupational; Carcinogens, Environmental; Cohort Studies; Diatomaceous Earth; Follow-Up Studies; Gold; Humans; Linear Models; Lung Neoplasms; Maximum Allowable Concentration; Mining; Occupational Diseases; Risk Assessment; Silicon Dioxide; Silicosis

Topics: Adult; Age of Onset; Calcium Carbonate; Construction Materials; Crystallization; Guideline Adherence; Humans; Lung Transplantation; Male; Mining; Occupational Exposure; Occupational Health; Particle Size; Quartz; Silicon Dioxide; Silicosis; Workers' Compensation

Granite countertop fabricators are at risk of exposure to respirable crystalline silica, which may cause silicosis and other lung conditions. The purpose of this study was to estimate the prevalence of exposure control methods, especially wet methods, in granite countertop fabrication in Oklahoma to assess how many workers might be at risk of overexposure to crystalline silica in this industry. Granite fabrication shops in the three largest metropolitan areas in Oklahoma were enumerated, and 47 of the 52 shops participated in a survey on fabrication methods. Countertop shops were small businesses with average work forces of fewer than 10 employees. Ten shops (21%) reported using exclusively wet methods during all fabrication steps. Thirty-five shops (74%) employing a total of about 200 workers reported using dry methods all or most of the time in at least one fabrication step. The tasks most often performed dry were edge profiling (17% of shops), cutting of grooves for reinforcing rods (62% of shops), and cutting of sink openings (45% of shops). All shops reported providing either half-face or full-face respirators for use during fabrication, but none reported doing respirator fit testing. Few shops reported using any kind of dust collection system. These findings suggest that current consumer demand for granite countertops is giving rise to a new wave of workers at risk of silicosis due to potential overexposure to granite dust.

Topics: Air Pollutants, Occupational; Dust; Health Surveys; Household Work; Humans; Inhalation Exposure; Interior Design and Furnishings; Occupational Diseases; Occupational Exposure; Oklahoma; Respiratory Protective Devices; Risk; Safety; Silicon Dioxide; Silicosis; Surveys and Questionnaires; Ventilation; Water; Workload

To assess mortality in Vermont granite workers and examine relationships between silica exposure and mortality from lung cancer, kidney cancer, non-malignant kidney disease, silicosis and other non-malignant respiratory disease. Methods Workers employed between 1947 and 1998 were identified. Exposures were estimated using a job-exposure matrix. Mortality was assessed through 2004 and standardised mortality ratios (SMRs) were computed. Associations between mortality and exposure to silica were assessed by nested case-control analyses using conditional logistic regression. Results 7052 workers had sufficient data for statistical analysis. SMRs were significantly elevated for lung cancer (SMR 1.37, 95% CI 1.23 to 1.52), silicosis (SMR 59.13, 95% CI 44.55 to 76.97), tuberculosis (SMR 21.74, 95% CI 18.37 to 25.56) and other non-malignant respiratory disease (SMR 1.74, 95% CI 1.50 to 2.02) but not for kidney cancer or non-malignant kidney disease. In nested case-control analyses, significant associations with cumulative exposure to respirable free silica were observed for silicosis (OR 1.13, 95% CI 1.05 to 1.21 for each 1 mg/m(3)-year increase in cumulative exposure) and other non-malignant respiratory disease (OR 1.10, 95% CI 1.03 to 1.16) but not for lung cancer (OR 0.99, 95% CI 0.94 to 1.03), kidney cancer (OR 0.96, 95% CI 0.84 to 1.09) or non-malignant kidney disease (OR 0.95, 95% CI 0.84 to 1.08). Conclusions Exposure to crystalline silica in Vermont granite workers was associated with increased mortality from silicosis and other non-malignant respiratory disease, but there was no evidence that increased lung cancer mortality in the cohort was due to exposure. Mortality from malignant and non-malignant kidney disease was not significantly increased or associated with exposure.

Topics: Aged; Aged, 80 and over; Epidemiologic Methods; Humans; Kidney Diseases; Kidney Neoplasms; Lung Neoplasms; Male; Middle Aged; Mining; Occupational Diseases; Occupational Exposure; Respiratory Tract Diseases; Silicon Dioxide; Silicosis; Vermont

To evaluate silica exposure and respiratory disease in granite workers.. A cross-sectional study of 440 active granite workers.. Seventy-seven (17.5%) have silicosis, complicated in 15 of them; 18 have an obstructive ventilatory defect and 73 had exceeded 3.5 mg/m-year of cumulative silica exposure. Percent predicted FEV1 have a significant negative relation with mg/m(3)-year (P < 0.001) with a trend toward dose-response excluding silicotics and controlling for tobacco. The odds ratio (95% confidence interval) of having a percent predicted FEV1 below 50th percentile is 1.18 (0.66 to 2.11) for nonexposed smokers, 1.47 (0.76 to 2.84) for exposed nonsmokers, and 2.07 (1.12 to 3.85) for exposed smokers, in comparison with the control group.. This study suggests that silica induces functional alteration regardless of silicosis and, in all likelihood, synergistically with tobacco. Exposure levels must be controlled better in these workers and those with silicosis must be relocated to risk-free jobs or retired.

Topics: Adolescent; Adult; Cross-Sectional Studies; Dose-Response Relationship, Drug; Environmental Pollutants; Forced Expiratory Volume; Humans; Male; Middle Aged; Occupational Exposure; Odds Ratio; Respiratory Tract Infections; Silicon Dioxide; Silicosis; Spain; Young Adult

To explore the healthy worker survivor effect (HWSE) in a study of Vermont granite workers by distinguishing "prevalent" from "incident" hires based on date of hire before or after the start of follow-up.. Records of workers between 1950 and 1982 were obtained from a medical surveillance programme. Proportional hazards models were used to model the association between silica exposure and lung cancer mortality, with penalised splines used to smooth the exposure-response relationship. A sensitivity analysis compared results between the original cohort and subcohorts defined by restricting date of hire to include varying proportions of prevalent hires.. Restricting to incident hires reduced the 213 cases by 74% and decreased the exposure range. The maximum mortality rate ratio (MRR) was close to twofold in all subcohorts. However, the exposure at which the maximum MRR was achieved decreased from 4.0 to 0.6 mg-year/m3 as the proportion of prevalent hires decreased from 50% in the original cohort to 0% in the subcohort of incident hires.. Despite loss in power and restricted exposure range, decreasing the relative proportion of prevalent to incident hires reduced HWSE bias, resulting in stronger evidence for a dose-response between silica exposure and lung cancer mortality.

Topics: Aged; Bias; Cohort Studies; Employment; Follow-Up Studies; Healthy Worker Effect; Humans; Incidence; Industry; Lung Neoplasms; Middle Aged; Prevalence; Proportional Hazards Models; Silicon Dioxide; Silicosis; Survival Analysis; Time Factors; Vermont

This mortality study extends the period of observation of an article published in 1988 of 5414 workers in Vermont granite sheds and quarries to assess whether previously reported reductions in silicosis and tuberculosis mortality were maintained. The relationship between lung cancer and quartz exposure is also examined by comparing mortality in workers hired before and after 1940, when dust controls were introduced and exposures were reduced by 80% to 90%. Before 1940, general stone shed air contained 20 million particles/cubic foot (mppcf) (approximately equivalent to 0.2 mg/m of quartz), and pneumatic chisel workers were exposed on average to 60 mppcf (approximately equivalent to 0.6 mg/m of quartz). Other workers had variable exposures. After 1940, a period of decline occurred in dust levels and then stabilized in approximately 1955, when average dust levels were 5 to 6 mppcf (equivalent to 0.05-.06 mg/m of quartz). Dust exposures in the Vermont industry is considered to be free of confounding occupational substances such as arsenic, although cigarette smoking was common. By the end of 1996, 2539 workers, or 46.9% of the cohort, had died. There were no silicosis deaths in workers hired after 1940 who were exposed only in the Vermont granite industry, illustrating the effect of lowering quartz exposures. Tuberculosis caused 2 deaths in those hired after 1940 (standardized mortality ratio [SMR] = 0.52; not significant). Overall lung cancer mortality was elevated in shed workers who had been exposed both to high levels of quartz before 1940 and to the lower levels prevailing after 1940 (SMR = 1.32; P < 0.01). Quarry workers did not show an excess of lung cancer (SMR = 0.73; not significant). When shed workers with high and low exposure histories (before and after 1940) but with comparable latency and tenure were contrasted, lung cancer mortality was similar. Differing levels of quartz exposure, which resulted in large differences in the mortality experience from silicosis, did not result in differences in lung cancer mortality. The results do not support the hypothesis that granite dust exposure has a causal association with lung cancer.

Topics: Cause of Death; Cohort Studies; Environmental Exposure; Extraction and Processing Industry; Humans; Lung Neoplasms; Male; Occupational Diseases; Quartz; Silicon Dioxide; Silicosis; Tuberculosis, Pulmonary; Vermont

This study was undertaken to assess the prevalence of radiographic abnormalities consistent with silicosis in a group of 600 retired granite workers who were receiving pensions. Files of regional clinics and hospitals were searched for chest radiographs taken on these men, and 470 x-ray films suitable for interpretation were located. After exclusions (women, and men who had worked in the granite industry elsewhere), 408 x-ray films were independently read by three experienced readers using the 1980 International Labour Office scheme. Dust exposures were estimated for workers hired after 1940, when the dust-control standard of 10 million particles per cubic foot (mppcf) (equivalent to 0.1 mg/m3) was put in place and monitored by the Vermont Division of Industrial Hygiene. Dust levels were initially high but were gradually reduced from 1940 to 1954, after which average quartz exposures stabilized to a mean of approximately 0.05 to 0.06 mg/m3; however, about 10% to 15% of samples after 1954 exceeded 0.1 mg/m3. Of the 408 x-ray films, 58 were taken on workers hired before dust controls were instituted in 1940, and 25.9% showed abnormalities (a profusion score of 1/0 or greater). A total of 350 x-ray films were taken on workers hired in 1940 or after, and the prevalence in this group was 5.7%. The radiographic changes in workers hired after 1940 are likely due to excessive exposures during the first 15 years of dust control. We conclude that if the exposure standard of 0.1 mg/m3 is rigorously observed in the workplace, radiographic abnormalities caused by quartz dust in long-term workers will be rare.

Topics: Aged; Aged, 80 and over; Cross-Sectional Studies; Dust; Humans; Male; Middle Aged; Radiography; Silicon Dioxide; Silicosis; Threshold Limit Values; Vermont

Low level effects of granite dust on one-second forced expiratory volume (FEV1) are estimated in 618 Vermont granite workers followed for 5 years with annual pulmonary function tests. Reduced pulmonary function has already been reported for the subset of subjects lost to follow-up (dropouts) suggesting possible bias in analyses based only on survivors.. Healthy worker selection bias is directly assessed by comparing the dose-response associations between survivors who remained in the study for the full 5-year observation period and the dropouts.. The 353 survivors had an FEV1 of 96% of predicted at baseline and were losing FEV1 at an average rate of 44 ml/yr. No association was found in this group between the rate of FEV1 decline and lifetime dust exposure. However, the 265 workers with incomplete follow-up, 'dropouts', had a lower FEV1 at baseline (94%) and were losing FEV1 at an average rate of 69 ml/yr. The dose-response parameter in this group was estimated to be 4 ml/yr loss per mg/m3-year and was statistically significant.. These results provide an illustration of bias due to the healthy worker effect and an example of the failure to detect a true work-related health effect in a study based only on a 'survivor' population.

Topics: Adult; Forced Expiratory Volume; Healthy Worker Effect; Humans; Longitudinal Studies; Male; Middle Aged; Mining; Population Surveillance; Regression Analysis; Silicon Dioxide; Silicosis; Vermont

Previous studies have suggested that excessive losses of FVC and FEV1 were occurring in Vermont granite workers despite the fact that mean quartz levels existing in the industry were below the current OSHA standard of 100 micrograms/m3. We reexamined these losses in granite workers over an 8-year period, testing the workforce biennially from 1979 to 1987. All workers, including stone shed, quarry, and office, were offered forced spirometry using a 10-L water-sealed spirometer (Collins). In the peak year of participation (1983), 887 workers out of a total of approximately 1,400 were tested. Estimates of longitudinal loss were based on 711 workers who participated in at least three of the surveys. The mean age of this group was 42.9 years, and the mean years employed was 19.3 years; 21.4 percent were non-smokers (NS), 34.2 percent were ex-smokers (ES), and 44.4 percent were current smokers (CS). Average annual losses of FVC were 0.018 (SD = 0.056) L (CS, 0.025 L; NS, 0.006 L: and ES, 0.016 L). Average annual losses of FEV1 were 0.030 (SD = 0.041) L (CS, 0.038 L; NS, 0.020 L; and ES, 0.027 L). Analysis of covariance indicated that losses were related to the initial values for FVC or FEV1, height, age, and smoking status. After adjusting for these variables, the losses of both FVC and FEV1 were not correlated with years employed in the granite industry. No significant differences existed in the loss of FVC or FEV1 in categories of workers exposed to different levels of granite dust, eg, office, quarry, and stone shed workers. The annual losses of pulmonary function were significantly smaller than those estimated previously, which were 0.070 to .080 L in FVC, and 0.050-0.070 L in FEV1. We conclude that dust levels in the Vermont granite industry, which have been in conformance with OSHA permissible exposure limits, do not accelerate pulmonary function loss.

Topics: Adult; Air Pollutants, Occupational; Dust; Forced Expiratory Volume; Humans; Longitudinal Studies; Male; Quartz; Respiratory Mechanics; Silicon Dioxide; Silicosis; Vital Capacity

Topics: Humans; Incidence; Mining; Prevalence; Silicon Dioxide; Silicosis; Spain

Of the 184 cases of silicosis registered between 1 January 1970 and 31 December 1984 in Singapore, all the relevant information was available for 159, which were linked to the population-based National Cancer Register for lung cancer. Nine cases of lung cancer were found. The standardized incidence ratio (SIR) was computed with the age- and calendar-specific incidence of lung cancer rates of Chinese males in Singapore as a basis. Excess risk of lung cancer was found (SIR 2.01, 95% confidence interval 0.92-3.81). Adjustment for smoking showed that it alone could not account for the excess lung cancer risk. There was an increasing, but not significant, trend with increasing severity of silicosis and exposure duration. The results suggest that the severity of silicosis and possibly exposure to free silica may have contributed to the excess of lung cancer among the cases of silicosis studied.

Topics: Cohort Studies; Dust; Humans; Lung Neoplasms; Male; Middle Aged; Mining; Occupational Diseases; Racial Groups; Risk Factors; Silicon Dioxide; Silicosis; Singapore; Smoking

Estimation of the exposure to respirable dust in the workplace is an important aspect of industrial hygiene. We performed bronchoalveolar lavage (BAL) on 42 healthy nonindustrial control subjects and 44 workers in the Barre, Vermont granite industry to determine whether BAL materials reflected occupational exposure. The granite workers held jobs with a range of dust exposure intensities and had employment histories from 1 to 43 yr; 12 workers were retired. None of the workers had radiologic evidence of silicosis. The granite dust content of BAL materials was measured by enumerating the percentage of cells positive for particulates by polarized light microscopy, by analysis for silicon by scanning electron microscopy with energy-dispersive X-ray spectrometry, and by chemical analysis. Minerals were present in greater quantity in the BAL cells from granite workers than from nonindustrial control subjects. Polarized light microscopy was comparable in sensitivity, specificity, and overall accuracy to electron microscopy; chemical analysis was less accurate than either microscopic technique. Tobacco smoking did not interfere with the detection of the occupationally related minerals or influence the quantity of dust present. The mineral in BAL cells was partially related to the intensity of exposure within the granite industry and to the duration of employment, but there was great individual variation among subjects. Retirement led to a decrease in BAL mineral content, but substantial dust remained for many years.

Topics: Bronchoalveolar Lavage Fluid; Female; Humans; Lung; Male; Microscopy, Electron, Scanning; Microscopy, Polarization; Middle Aged; Occupational Exposure; Retirement; Silicon Dioxide; Silicosis; Time Factors; Vermont

In a sample of 186 stone workers who performed granite "tearing" and "stone work" (either manual or mechanical) we have found silicosis in 50.5% (simple silicosis 47.3%, and complicated silicosis 3.2%). The most commonly found radiologic manifestation was a round opacity type "p" and a 1/1 to 1/3 profusion. From a functional respiratory perspective, a mild reduction of FVC, DLco (SB) and pO2 similar to that described in coal miners' pneumoconiosis was observed. It seems that "stone workers" had a higher incidence of suffering severe silicosis than stone "tearing" workers. Surprisingly, in the analysis of inhaled dust of such an activity which is performed in the open air the rates of dust and SiO2 are much higher than those found in coal workers. We believe that this is the first time that these measurements are performed, and published, in a group of stone workers.

Topics: Humans; Incidence; Lung; Mining; Radiography; Respiratory Function Tests; Silicon Dioxide; Silicosis; Spain

The frequency and correctness of respirators were studied in 5 granite quarries in Singapore involving 201 workers. The overall prevalence of usage of correct respirators was 45.8%. 10.4% of the workers were found to be using the wrong respiratory protective devices. Age, years of exposure and types of occupations were found to affect the usage of respirators. Some common reasons given by workers for not wearing the respirators were 'breathing difficulty', 'hot & sweaty', and 'respirator smells after a while'.

Topics: Adult; Aged; Dust; Humans; Male; Middle Aged; Mining; Protective Devices; Respiratory Protective Devices; Risk Factors; Silicon Dioxide; Silicosis; Singapore

A cohort mortality study was carried out in Vermont granite workers who had been employed between the years 1950 and 1982. The cohort included men who had been exposed to high levels of granite dust prior to 1938-1940 (average cutters to 40 million parts/cubic foot), and those employed at dust levels after 1940, which on average were less than 10 million parts/cubic foot. Deaths were coded by a qualified nosologist and standardized mortality ratios were calculated. The results confirm previous studies that show that death rates from silicosis and tuberculosis, the major health threats in the years before 1940, were essentially eliminated after dust controls. However, we found excessive mortality rates from lung cancer in stone shed workers who had been employed prior to 1930, and hence had been exposed to high levels of granite dust. When information was available, 100% of those dying from lung cancer had been smokers.

Topics: Adult; Aged; Humans; Lung Neoplasms; Male; Middle Aged; Mortality; Risk Factors; Silicon Dioxide; Silicosis; Silicotuberculosis; Smoking; Vermont

The proportional mortality experience (1952-1978) of 969 deceased white male granite workers was compared with that of United States white males. Industrial hygiene information was combined with work histories to develop an estimate of lifetime granite dust exposure for each individual. Subjects were grouped into four cumulative exposure categories, and exposure-response relationships were examined. Trends of increasing silicosis and tuberculosis with increasing lifetime exposure were observed. These are consistent with earlier findings. With the exception of excess suicide among granite workers dying before 1970, there was little evidence of association between other causes of death and employment in the granite industry.

Topics: Adult; Humans; Lung Neoplasms; Male; Middle Aged; Neoplasms; Occupational Diseases; Regression Analysis; Silicon Dioxide; Silicosis; Silicotuberculosis; Suicide; United States; Vermont

Topics: Air Pollution; Dust; Humans; Mass Chest X-Ray; Preventive Medicine; Silicon Dioxide; Silicosis; Statistics as Topic; Vermont

Topics: England; Humans; Silicon Dioxide; Silicosis

Topics: Czechoslovakia; Disability Evaluation; Humans; Radiography, Thoracic; Silicon Dioxide; Silicosis

Topics: Biometry; Data Collection; Silicon Dioxide; Silicosis; Singapore

Topics: Biomedical Research; Humans; Silicon Dioxide; Silicosis; Vermont

Topics: Biomedical Research; Dust; Humans; Industry; Silicon Dioxide; Silicosis; Vermont

Topics: Data Collection; Humans; Industry; Silicon Dioxide; Silicosis

Topics: Data Collection; Georgia; Health; Humans; Silicon Dioxide; Silicosis

Topics: Georgia; Humans; Industry; Pneumoconiosis; Silicon Dioxide; Silicosis