Dusty Trades Research Articles

Colinet–Caplan Syndrome: History of an Outbreak of Autoimmune Disease in Scouring Powder Workers

The first modern description linking rheumatoid arthritis to occupational dust exposure is generally attributed to the British physician Anthony Caplan. In 1953, Caplan reported on a “peculiar” nodular pattern on chest radiographs of Welsh coal miners with rheumatoid arthritis that differed from the typical coal workers' pneumoconiosis. However, as early as 1950, the Belgian rheumatologist Émile Colinet described a similar case of rheumatoid arthritis and concomitant pulmonary opacities in a 30-year-old woman with silica exposure. Soon after, he published a second case. Although this condition initially was called Colinet–Caplan syndrome in the Francophone biomedical literature, Colinet's name was later dropped from the eponym. Because Colinet never clearly described the specific occupational context of his cases, Caplan syndrome has been misconstrued as uniquely a disease of coal miners. We attempted to reconstruct the working conditions of Colinet's patients and found that they were packing Vim, a silica-based scouring powder, at the Savonneries Lever Frères factory in Brussels, Belgium. Colinet's cases were only the first 2 in a series of reports of rheumatoid arthritis and other autoimmune diseases, mainly among young women, in those who worked in the production of silica-based scouring powder between the 1930s and 1980s across Europe. The largest outbreak involved 32 cases of autoimmune disease among 50 former workers of a Spanish scouring powder manufacturing facility. After silica in scouring powders was replaced with less hazardous materials later in the 20th century, no further cases have been reported. Although scouring powder disease is a historical phenomenon, autoimmune disorders linked to occupational exposure to silica and coal dust have not disappeared but instead are reemerging among those who work with silica-based artificial stone and in other dusty trades.

Dusty trades and associated rheumatoid arthritis in a population-based study in the coal mining counties of Appalachia

ObjectivesWe previously showed increased coal mining-associated risk of rheumatoid arthritis (RA). Using additional survey data, we sought to delineate this risk further.MethodsWe used data from two cross-sectional, random-digit-dial, population-based surveys...

Occupational Health: Lunar Lung Disease

With the National Aeronautics and Space Administration (NASA) finalizing plans to begin construction on a manned lunar outpost by 2020, the sun is rising on a whole new world of environmental and occupational health. Could longer space missions, reduced gravity, and moondust be a dangerous combination for lunar astronauts’ pulmonary health? Results published in the August 2008 issue of the European Journal of Applied Physiology suggest so. “Moondust has properties similar to silica, a mineral commonly encountered in mining operations known to cause silicosis and other lung problems,” explains principal investigator Kim Prisk, a researcher with the Human Factors and Performance Team at the National Space Biomedical Research Institute. “To be safe we need to know how much dust can get into astronauts’ airways, where it deposits, how long it stays, and just how toxic it might be.” Such information is essential to mission designers who must know what air purification equipment to haul moonward and how extensive post-moonwalk decontamination procedures must be in order to clean up the clingy dust. To determine how much and where moondust might deposit in the lungs, Prisk’s team performed experiments under lunar gravity conditions during parabolic flights aboard NASA’s Microgravity Research Aircraft. Up to six subjects breathed in aerosols (104 particles/mL) of 0.5- or 1-μm polystyrene latex beads (representative of moondust particle sizes) at a constant rate through a mouthpiece. The number of beads entering and leaving the subjects’ breath was measured using a photometer, which revealed how much “dust” remained in subjects’ airways. Compared with terrestrial conditions, lunar gravity reduced the total quantity of 0.5-μm beads settling in the airways by 25% and 1-μm beads by 32%, explains first author Chantal Darquenne, an associate professor in the Department of Medicine at the University of California, San Diego. But while this may seem like good news, further experiments showed that the beads that settled were more likely to do so in the alveoli, clearance from which may be difficult. Whereas particles would be deposited in the upper airways under terrestrial conditions, under lunar conditions they would remain available to be eventually transported deeper into the lung. “NASA is learning that [different] moondusts have toxicologically worrisome properties including reactive surfaces, large surface areas per unit mass, a high content of particles greater than 0.1 μm, and metallic iron impregnation,” says John James, chief toxicologist at the NASA Johnson Space Center in Houston, Texas. “We must be careful not to suppose that there is one level of toxicity for lunar dust,” he adds. “It is likely that there is considerable variability in the size distribution and mineral composition of dust from one location to another. This could mean several-fold variability in the inherent toxicity of the dusts.” “Occupational dust diseases can take decades to develop among exposed workers on Earth, but if the alveoli are more affected on the moon and clearance is reduced, disease could develop more quickly in astronauts—especially if lunar dust proves very toxic,” says David Goldsmith, an associate research professor of environmental and occupational health at The George Washington University in Washington, DC. Emphasizing that we should recognize moondust-exposed astronauts as dusty trades workers in space, he points out that chronic silica exposure can also lead to lung cancer, kidney ailments, and autoimmune diseases in occupationally exposed workers on Earth. He adds, “In space and on Earth these conditions are fully preventable with proper respiratory protection including engineering controls.” This high-flying research may also have a down-to-Earth application. By determining where particles of different size settle in the airways under terrestrial gravity conditions, it may be possible to learn how to deliver drugs accurately to different areas of the lungs.

Occupational exposures and COPD: an ecological analysis of international data

The occupational contribution to chronic obstructive pulmonary disease (COPD) has yet to be put in a global perspective. In the present study, an ecological approach to this question was used, analysing group-level data from 90 sex-specific strata from 45 sites of the Burden of Obstructive Lung Disease study, the Latin American Project for the Investigation of Obstructive Lung Disease and the European Community Respiratory Health Survey follow-up. These data were used to study the association between occupational exposures and COPD Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II or above. Regression analysis of the sex-specific group-level prevalence rates of COPD at each site against the prevalence of occupational exposure and ever-smoking was performed, taking into account mean smoking pack-yrs and mean age by site, sex, study cohort and sample size. For the entire data set, the prevalence of exposures predicted COPD prevalence (0.8% increase in COPD prevalence per 10% increase in exposure prevalence). By comparison, for every 10% increase in the proportion of the ever-smoking population, the prevalence of COPD GOLD stage II or above increased by 1.3%. Given the observed median population COPD prevalence of 3.4%, the model predicted that a 20% relative reduction in the disease burden (i.e. to a COPD prevalence of 2.7%) could be achieved by a 5.4% reduction in overall smoking rates or an 8.8% reduction in the prevalence of occupational exposures. When the data set was analysed by sex-specific site data, among males, the occupational effect was a 0.8% COPD prevalence increase per 10% change in exposure prevalence; among females, a 1.0% increase in COPD per 10% change in exposure prevalence was observed. Within the limitations of an ecological analysis, these findings support a worldwide association between dusty trades and chronic obstructive pulmonary disease for both females and males, placing this within the context of the dominant role of cigarette smoking in chronic obstructive pulmonary disease causation.

Commentary: George W. Comstock's Contributions to Respiratory Disease Epidemiology

George W. Comstock’s career spanned a remarkable era in the epidemiology of respiratory diseases. At its beginning, tuberculosis was a leading cause of death, and the emerging epidemics of lung cancer and chronic obstructive pulmonary disease (COPD) were being recognized. Occupational lung diseases were common among workers in dusty trades, industry, and mining. At its end, tuberculosis had been largely controlled in many of the more developed countries, including the United States, as had many of the major occupational lung diseases. Unfortunately, the dual epidemics of smokingcaused lung disease—lung cancer and COPD—were still causing increasing numbers of deaths even though the causes of most cases of disease had been identified. Not surprisingly, given Comstock’s broad reach and curiosity, his studies on respiratory health extended beyond tuberculosis to cigarette smoking, indoor and outdoor air pollution, and COPD. The decades of his career also saw the development of carefully standardized methods for the study of respiratory diseases. These methods were first developed in the United Kingdom by Cochrane, Fletcher, and others for investigating the causes and natural history of chronic lung diseases. Benjamin Ferris (1), a physiologist at the Harvard School of Public Health, brought these methods to the United States for his pioneering air pollution studies. Comstock contributed to one of the major efforts to adapt these methods for use in the United States. He was a key participant in the American Thoracic Society’s Epidemiology Standardiza

Occupational exposures and the risk of COPD: dusty trades revisited

Background:The contribution of occupational exposures to chronic obstructive pulmonary disease (COPD) and, in particular, their potential interaction with cigarette smoking remains underappreciated.Methods:Data from the FLOW study of 1202 subjects with...

Crystalline Silica is a Negative Modifier of Pulmonary Cytochrome P-4501A1 Induction

Polycyclic aromatic hydrocarbons (PAHs) are products of incomplete combustion that are commonly inhaled by workers in the dusty trades. Many PAHs are metabolized by cytochrome P-4501A1 (CYP1A1), which may facilitate excretion but may activate pulmonary carcinogens. PAHs also stimulate their own metabolism by inducing CYP1A1. Recent studies suggest that respirable coal dust exposure inhibits induction of pulmonary CYP1A1 using the model PAH β-naphthoflavone. The effect of the occupational particulate respirable crystalline silica was investigated on PAH-dependent pulmonary CYP1A1 induction. Male Sprague-Dawley rats were exposed to intratracheal silica or vehicle and then intraperitoneal β-naphthoflavone, a CYP1A1 inducer, and/or phenobarbital, an inducer of hepatic CYP2B1, or vehicle. β-Naphthoflavone induced pulmonary CYP1A1, but silica attenuated this β-naphthoflavone-induced CYP1A1 activity and also suppressed the activity of CYP2B1, the major constituitive CYP in rat lung. The magnitude of CYP activity suppression was similar regardless of silica exposure dose within a range of 5 to 20 mg/rat. Phenobarbital and β-naphthoflavone had no effect on pulmonary CYP2B1 activity. Both enzymatic immunohistochemistry and immunofluorescent staining for CYP1A1 indicated that sites of CYP1A1 induction were nonciliated airway epithelial cells, endothelial cells, and the alveolar septum. Using immunofluorescent colocalization of CYP1A1 with cytokeratin 8, a marker of alveolar type II cells, the proximal alveolar region was the site of both increased alveolar type II cells and decreased proportional CYP1A1 expression in alveolar type II cells. Our findings suggest that in PAH-exposed rat lung, silica is a negative modifier of CYP1A1 induction and CYP2B1 activity.

Clinically important FEV1 declines among coal miners: an exploration of previously unrecognised determinants.

OBJECTIVES: The relation between occupational exposure to dust and loss of ventilatory lung function is now well established. However, many exposures during work and other activities might also have important...

Quartz – The Most Abundant Mineral Species in the Earth's Crust and a Human Carcinogen?

Quartz – the most abundant mineral species in the Earth's crust – has recently been deemed a human carcinogen, with the main threat to humans being from inhalation and, in turn, the development of lung cancer. This action was taken by the International Agency for Research on Cancer (IARC) and was based upon substantial clinical and experimental evidence in humans and animals and in vitro experiments. As a result, the U.S. Occupational Safety and Health Administration (OSHA) now requires all manufacturers of materials that contain above 0.1% quartz to label their products as “probable human carcinogens.” Concurrently, the U.S. Environmental Protection Agency (EPA) requires communities to monitor PM10 (particulate matter less than 10 microns in diameter) in the air, because high levels of PM10 have been linked to increased risk of respiratory diseases.A major component of PM10 is quartz. Long-term inhalation of large amounts of quartz-rich dust has led to various respiratory diseases in the mining industry and other dusty trades, but could low-level exposure to quartz lead to lung cancer in the general population? These recent rulings and current and future regulations have serious economic implications on the mining and farming industries in the United States and may even limit the rock and mineral collections students are “exposed” to in academic settings.

Effects of Exposure Estimation Procedures on the Evaluation of Exposure-Response Relationships for Silicosis

The reconstruction of exposures in occupational epidemiology is an important and expanding research interest. Historically the number of environmental measurements available has been small. Methods used to estimate exposure for jobs during time periods for which there are few or no sample results incude: assign zero exposure, use the average exposure for jobs not evaluated, estimate exposure for only some jobs over specified time periods, estimate exposure for all jobs and time periods using a single-step procedure such as calculation of an average (Theriault et al., 1974) or a multi-step imputation process involving considerations such as engineering controls and similarity of processes (Dement et al., 1983; Seixas et al., 1991; Stewart et al., 1995). The work reported here was undertaken to provide insight into possible influences of assumptions made regarding missing exposure data on measures of association, by comparing the results at each step of a multi-step imputation algorithm. Data for silica exposure and X-ray diagnosis of silicosis from the North Carolina Dusty Trades program have been used. A previous report included a strong, linear exposure-response relationship (Rice et al., 1986); however, all exposure estimates were based on measurement data. If measurements were not available, exposure was assumed to be zero. For this report, odds ratios for silicosis have been calculated after each of five steps in an imputation algorithm and are contrasted with the original results.

Radiographic Evidence of Silicosis in Relation to Silica Exposure

Abstract Although the risk of silicosis has long been recognized as a consequence of exposure to crystalline silica, there are only limited data available for quantitatively estimating risk in relation to modern concentrations. Reports on three large groups of workers (Vermont granite workers, South African gold miners, and Ontario hardrock miners) form the basis for estimating silicosis risk; two other smaller studies, of British gypsum miners and North Carolina dusty trades workers, provide additional but less quantitative information. For 40 years of exposure to a respirable silica concentration of 0.1 mg/m3, the estimated cumulative risk of radiographic evidence of silicosis is approximately 1 to 3 percent based on the Ontario miners (depending on whether diagnosis requires a positive reading by a majority of five readers or by only one reader) and is 60 percent based on South African miners. Findings from Vermont granite workers and North Carolina dusty trades workers are more consistent with the low...

The North Carolina Dusty Trades Database: A Resource for Assessment of Silica Exposure Since 1935

Abstract Since 1935 the state of North Carolina has designated industries where a worker might be potentially exposed to the hazards of silicosis, conducted studies of workplace conditions, recommended measures to reduce hazardous exposures, and performed preemployment and follow-up medical evaluations. Advantages of these accumulated data include: duration of the surveillance program; documented sampling/analytical methods; a wide range of industries (granite dimension stone, crushed stone, lithium, tungsten, pyrophyllite, feldspar, mica, kaolin, talc, quartz, foundry); the flexibility to construct several exposure metrics; and a companion medical surveillance program. Limitations include: absence of data for some workplaces; fluctuations in the scope of the program over time; the need to convert between sampling methods; and limited independent validation of formulas to combine impinger results. Nonetheless, the data still being amassed represent a unique record for the study of the risk of adverse heal...

Reevaluation of silicosis and lung cancer in North Carolina dusty trades workers : Amandus H.E. Castellan R.M. Shy C. Heineman E.F. Blair A. DRDS/NIOSH, 944 Chestnut Ridge Road, Morgantown, WV 26505-2888. Am J Ind Med 1992;22:147–153

Reevaluation of silicosis and lung cancer in North Carolina dusty trades workers : Amandus H.E. Castellan R.M. Shy C. Heineman E.F. Blair A. DRDS/NIOSH, 944 Chestnut Ridge Road, Morgantown, WV 26505-2888. Am J Ind Med 1992;22:147–153

Silicosis and lung cancer in North Carolina dusty trades workers : Amandus HE, Shy C, Wing S, Blair A, Heineman EF. Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, 944 Chestnut Ridge Road, Morgantown, WV 26505-2888. Am J Ind Med 1991;20:57–70

Silicosis and lung cancer in North Carolina dusty trades workers : Amandus HE, Shy C, Wing S, Blair A, Heineman EF. Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, 944 Chestnut Ridge Road, Morgantown, WV 26505-2888. Am J Ind Med 1991;20:57–70

Mortality among dust-exposed Chinese mine and pottery workers.

A cohort study of approximately 68,000 persons employed during 1972 to 1974 at metal mines and pottery factories in south central China was conducted to evaluate mortality from cancer and other diseases among workers exposed to different levels of silica and other dusts. A follow-up of subjects through December 31, 1989 revealed 6,192 deaths, a number close to that expected based on Chinese national mortality rates. There was, however, a nearly 6-fold increase in deaths from pulmonary heart disease (standard mortality ratio, 581; 95% confidence interval 538 to 626), and a 48% excess of mortality from nonmalignant respiratory diseases (standard mortality ratio, 148; 95% confidence interval, 139 to 158), primarily because of a more than 30-fold excess of pneumoconiosis. Pulmonary heart disease and noncancerous respiratory disease rates rose in proportion to dust exposure. Cancer mortality overall was not increased among the miners or pottery workers. There was no increased risk of lung cancer, except among tin miners, and trends in risk of this cancer with increasing level of dust exposure were not significant. Risks of lung cancer were 22% higher among workers with than without silicosis. The findings indicate that respiratory disease continues to be an occupational hazard among Chinese miners and pottery workers, but that cancer risks are not as yet strongly associated with work in these dusty trades.

Reevaluation of silicosis and lung cancer in North Carolina dusty trades workers.

We previously reported on the lung cancer mortality through 1983 of 760 males who were diagnosed with silicosis during 1930-1983 by the State of North Carolina's medical examination program for dusty trades workers. The lung cancer SMR (95% confidence interval) was 2.6 (1.8-3.6) among 655 white members of this group. In this paper, we report the results of a reanalysis of mortality among a subgroup for whom chest radiographs were currently available for rereading. Technically acceptable radiographs were available for 306 white males and were independently reclassified for pneumoconiosis by 3 "B" readers using the 1980 ILO Classification. Lung cancer SMRs were 1.7 (0.8-3.1) for the entire group of 306 white males, 2.5 (1.1-4.9) for 143 subjects reclassified as simple silicosis, and 1.0 (0.1-3.5) for 96 subjects whose radiographs were reclassified as ILO category 0. There were no lung cancer deaths among 67 subjects whose radiographs were reclassified as progressive massive fibrosis. Corresponding lung cancer SMRs for subjects who had never been employed in a job with exposure to known occupational carcinogens were 1.2 (0.2-4.4) for those reclassified as category 0, and 2.4 (1.0-5.0) for those reclassified as having simple silicosis. The age-adjusted lung cancer rate ratio among subjects with simple silicosis compared to those with category 0 was 1.5 (0.4-5.8). Our findings from this reanalysis, which effectively controls for misclassification of silicosis due to errors in radiograph interpretation by North Carolina program readers, offer additional evidence consistent with the hypothesis of an association between silicosis and lung cancer in this study group.

Silicosis and lung cancer in north Carolina dusty trades workers

Since 1940, 760 cases of silicosis have been diagnosed as part of the State of North Carolina's (NC) pneumoconiosis surveillance program for dusty trades workers. Vital status was ascertained through 1983 for 714 cases that had been diagnosed since 1940 and death certificates were obtained for 546 of the 550 deceased. Mortality from tuberculosis, cancer of the intestine and lung, pneumonia, bronchitis, emphysema, asthma, pneumoconiosis, and kidney disease was significantly increased in whites. Mortality from tuberculosis, ischemic heart disease, and pneumoconiosis was significantly increased in non-whites. The standardized mortality ratio (95% CI) for lung cancer based on U.S. rates was 2.6 (1.8-3.6) in whites, 2.3 (1.5-3.4) in those who had no exposure to other known occupational carcinogens, and 2.4 (1.5-3.6) in those who had no other exposure and who had been diagnosed for silicosis while employed in the NC dusty trades. Age-adjusted lung cancer rates in silicotics who had no exposure to other known occupational carcinogens were 1.5 (.8-2.9) times higher than that in a referent group of coal miners with coalworkers' pneumoconiosis (CWP) and 2.4 (1.5-3.9) times higher than that in a referent group of non-silicotic metal miners. Age- and smoking-adjusted rates in silicotics were 3.9 (2.4-6.4) times higher than that in metal miners. This analysis effectively controls for confounding by age, cigarette smoking, and exposure to other known occupational carcinogens, and it is unlikely that other correlates of silica exposure could explain the excess lung cancer mortality in the silicotics.

Epidemiologic Studies of Inorganic Dust-Related Lung Diseases in the Netherlands

The results of two epidemiologic investigations on dust-related lung diseases are presented. The two studies had different aims and designs. A cross-sectional study was done to investigate the silicosis prevalence in Dutch fine ceramic workers. In the small ceramic workshops in the Gouda region, simple pneumoconiosis is still commonly present (13.3%), whereas the silicosis prevalence in the highly mechanized industries is low (1.7%). Furthermore, heavy smoking seems to enhance the risk for silicosis after long-term exposure to quartz. A case-control study was performed to analyze the relation between dust exposure in the fine ceramic and coal mining industries and lung cancer. No relation between a work history in the dusty trades and lung cancer emerged, and a correlation with a specific histologic tumor cell type could not be demonstrated. Apparently, workers in the Dutch fine ceramic or coal mining industry have no increased risk of developing lung malignancies.

Factors Affecting Latency of Silicosis Development in North Carolina

A case series of silicotics employed in the North Carolina dusty trades is presented. Working lifetimes quartz exposure summaries are estimated using both the simple cumulative, and weighted models. Linear regression techniques are applied to study the latency in disease development, using the time from first exposure to diagnosis as the dependent variable. In addition to quartz exposure, race, age at first exposure, smoking history and year of diagnosis, the magnitude of the peak quartz exposure and the timing of the peak exposure in the work history were found to be important independent variables. For the cumulative and weighted model exposure estimates the multiple correlation coefficient were approximately 0.44 (p < 0.0001) and (p < 0.0001), respectively.

Reconstruction of silica exposure in the North Carolina dusty trades.

The current occupational standard for quartz exposure is largely drawn from studies of the granite workers at Barre, Vermont. Since 1935, the North Carolina Dusty Trades program has accumulated data on work-place environmental conditions, occupational history and health status for persons exposed to silica in a broad range of mineral industries, including granite dimension stone. The environmental data have been collected with Greenburg-Smith and midget impingers and the respirable mass dust sampler. A procedure is presented to combine the results of these sampling methods and estimate exposure at the various jobs at each dusty trades plant. From an individual's occupational history, the environmental exposure estimates are used to formulate personal lifetime exposure summaries. The results of this procedure in the North Carolina granite industry compared well with historical data from Vermont granite sheds.