vermiculite and Pleural-Diseases

This epidemiological study was conducted to determine whether high-resolution computed tomography (HRCT) is useful to screen for pulmonary abnormalities in people exposed to vermiculite containing asbestos. During June-September 2001, we evaluated HRCT of 353 people in Libby, MT, who had been exposed to asbestiform minerals associated with vermiculite. Of these, 334 participants of the summer 2000 medical testing program underwent HRCT of the chest at St. John's Lutheran Hospital and 19 eligible people who recently had undergone an HRCT scan at the same facility and under the same testing protocol allowed the study reviewers to use that scan. All 353 study participants were former vermiculite mine/mill workers (n = 55), their household contacts (n = 99), and people exposed to vermiculite through recreational or other activities (n = 199). Participants' 2000 medical testing results indicated only one of the three B-reader chest radiograph reviewers had reported a pleural abnormality (indeterminate chest radiograph). Three expert computer tomography (CT) scan evaluators reviewed the HRCT scans and identified pleural abnormalities in 98 (27.8%) of the 353 participants whose previous chest radiographs were classified indeterminate. Of these 98 people, 69 (70.4%) were either former vermiculite mine/mill workers or household contacts, and 40 (40.8%) showed pleural calcification on HRCT. Thirty out of the 40 people with pleural calcification reported having no occupational exposure to either Libby vermiculite or asbestos. Our findings indicate that low-dose HRCT can be considered for screening certain former vermiculite mine/mill workers and their household contacts who have indeterminate chest radiographs and may be useful for diagnosing a suspicious finding on a chest radiograph, particularly in a high-risk person.

Topics: Adult; Aged; Aluminum Silicates; Asbestos; Calcinosis; Epidemiologic Studies; Female; Humans; Male; Mass Screening; Middle Aged; Mining; Montana; Pleural Diseases; Radiography, Thoracic; Sensitivity and Specificity; Tomography, X-Ray Computed

This article describes radiologic and pulmonary function findings among miners exposed to Libby amphibole. Computed tomography (CT) permits the detection of the characteristic thin, lamellar pleural thickening (LPT).. Individuals who worked at the mine for a minimum of 6 months had chest CT and pulmonary function tests.. Pleural thickening was noted in 223 (87%) of the 256 miners, parenchymal abnormalities in 49 (19%). LPT, found in 151 (68%), was associated with low values of forced vital capacity and diffusion capacity and significantly lower values in all pulmonary function tests when associated with parenchymal abnormalities.. Eighty-seven percent of miners exposed to Libby Amphibole had pleural abnormalities on CT. LPT alone, and more so with parenchymal abnormalities, resulted in decreased pulmonary function. The importance of this easily missed LPT is demonstrated by its high frequency and significant functional effects.

Topics: Adult; Aged; Aluminum Silicates; Asbestos, Amphibole; Female; Forced Expiratory Volume; Humans; Male; Middle Aged; Mining; Montana; Occupational Diseases; Occupational Exposure; Pleura; Pleural Diseases; Pulmonary Diffusing Capacity; Tomography, X-Ray Computed; Vital Capacity

This study was conducted to assess associations of pleural plaques (PP) and longitudinal lung function in vermiculite miners of Libby, Montana who are occupationally exposed to asbestos. High-resolution computed tomography (HRCT) was used to identify asbestos-related findings in former Libby vermiculite miners. We investigated annual lung function decline in miners with PP only and compared them to miners with normal HRCT findings.. HRCTs from 128 miners were categorized into the following 4 diagnostic groups: (1) normal computed tomography scan (n = 9); (2) PP only (n = 72); (3) PP and interstitial fibrosis (n = 26) and (4) additional HRCT abnormalities (n = 21) such as rounded atelectasis, diffuse pleural thickening, pleural effusions or pulmonary nodules or tumor >1cm in diameter. Random intercept and slope linear mixed-effect regression models identified differences in lung function decline between miners with asbestos-associated outcomes and those with normal HRCT. Models were adjusted for follow-up time, body mass index, smoking status, latent exposure period and employment years. Interactions for smoking status with age and smoking status with pleural plaque severity were examined.. Miners with PP only did not have an accelerated decline in lung function between 40 and 80 years. Miners with PP and additional HRCT abnormalities displayed significantly accelerated declines in forced expiratory volume in 1 second and diffusing capacity of the lungs for carbon monoxide (P = 0.05 and P < 0.01, respectively). Plaque severity did not affect lung function decline. However, smokers with extensive plaques displayed accelerated loss in diffusing capacity of the lungs for carbon monoxide and forced expiratory volume in 1 second when compared to nonsmoking miners with mild plaque formation.. PP alone did not significantly affect lung function decline in vermiculite miners of Libby, Montana.

Topics: Aged; Aluminum Silicates; Asbestos, Amphibole; Humans; Longitudinal Studies; Lung; Male; Middle Aged; Miners; Montana; Occupational Exposure; Pleural Diseases; Respiratory Function Tests; Retrospective Studies; Tomography, X-Ray Computed

In the 2014 Integrated Risk Information System (IRIS) assessment for Libby amphibole asbestos (LAA), US EPA calculated a reference concentration (RfC) based on the prevalence of pleural plaques in a group of vermiculite workers in Marysville, Ohio. This RfC is based on the assumption that pleural plaques are associated with adverse lung function. In this study, we evaluated the association between pleural plaques and lung function in the Marysville worker cohort to determine whether they are associated with adverse effects or, rather, are more likely a biomarker of cumulative exposure to LAA.. We obtained the dataset on the Marysville worker cohort from University of Cincinnati, which included information on demographics, occupational exposures and results of chest high-resolution computed tomography (HRCT)/computed tomography (CT) scans and pulmonary function tests (PFTs). We used multivariate linear regression to estimate mean differences in several lung function parameters, and logistic regression to evaluate the odds of abnormal ventilatory patterns, among men with different pulmonary findings on HRCT/CT scans.. No statistically significant differences in FEV1, FVC, FEV1/FVC, TLC, RV or DLCO were observed between workers with normal scans and those with pleural plaques but no other abnormalities. In contrast, workers with other abnormal findings had statistically significant lower FEV1, FVC, TLC and DLCO, compared with those with normal scans.. This study does not indicate that pleural plaques have a significant effect on lung function when past asbestos exposure is accounted for.

Topics: Aged; Aluminum Silicates; Asbestos, Amphibole; Cohort Studies; Humans; Lung; Male; Middle Aged; Occupational Diseases; Occupational Exposure; Pleural Diseases; Respiratory Function Tests; Tomography, X-Ray Computed

Multiple studies have investigated the relationship between asbestos-related pleural plaques (PPs) and lung function, with disparate and inconsistent results. Most use chest radiographs to identify PPs and simple spirometry to measure lung function. High-resolution CT (HRCT) scanning improves the accuracy of PP identification. Complete pulmonary function tests (PFTs), including spirometry, lung volumes, and diffusing capacity of the lung for carbon monoxide, provide a more definitive assessment of lung function. The goal of this study was to determine, using HRCT scanning and complete PFTs, the effect of PPs on lung function in Libby vermiculite miners.. The results of HRCT scanning and complete PFTs performed between January 2000 and August 2012 were obtained from the medical records of 166 Libby vermiculite miners. Multivariate regression analyses with Tukey multivariate adjustment were used to assess statistical associations between the presence of PPs and lung function. Adjustments were made for age, BMI, smoking history, duration of employment, and years since last occupational asbestos exposure.. Nearly 90% of miners (n = 149) had evidence of PPs on HRCT scan. No significant differences in spirometry results, lung volumes, or diffusing capacity of the lung for carbon monoxide were found between miners with PPs alone and miners with normal HRCT scans. Miners with both interstitial fibrosis and the presence of PPs had a significantly decreased total lung capacity in comparison with miners with normal HRCT scans (P = .02). Age, cumulative smoking history, and BMI were significant covariates that contributed to abnormal lung function.. Asbestos-related PPs alone have no significant effect on lung function in Libby vermiculite miners.

Topics: Aged; Aluminum Silicates; Asbestos; Humans; Lung; Male; Middle Aged; Mining; Pleural Diseases; Pulmonary Diffusing Capacity; Respiratory Function Tests; Retrospective Studies; Spirometry; Tomography, X-Ray Computed

To examine the association between cumulative fiber exposure and health outcomes in workers (n = 336) with Libby amphibole exposure.. Exposure-response relationships were explored by the use of logistic regression, with cumulative fiber exposure modeled in categories and as a continuous variable.. The use of spline functions with lifetime cumulative fiber exposure as a continuous variable showed that the odds of localized pleural thickening were significantly elevated at less than 1 f/cc-y. Odds of parenchymal abnormalities, restrictive spirometry, and chronic bronchitis were also significantly elevated at 108, 166, and 24 f/cc-y, respectively.. The odds of several pulmonary health outcomes are correlated with cumulative exposure to Libby amphibole. That relatively low-lifetime cumulative exposures are associated with localized pleural thickening has implications for the non-cancer-risk assessment for Libby amphibole.

Topics: Aged; Aluminum Silicates; Asbestos, Amphibole; Bronchitis; Cohort Studies; Female; Humans; Lung; Male; Middle Aged; Occupational Diseases; Occupational Exposure; Pleural Diseases; Respiratory Function Tests; Risk Assessment; Spirometry

In 2000, the Agency for Toxic Substances and Disease Registry (ATSDR; Atlanta, GA, USA) investigated lung disease in those exposed to the tremolite-contaminated vermiculite mine in Libby, MT, USA. Previously unreported spirometric results are presented here in relation to exposure and radiographic findings. 4,524 study participants were assigned to one of seven mutually exclusive exposure categories. Associations among radiographic findings, spirometric results and exposure were investigated, along with the effect of a reduction in exposure potential when production was moved to a wet process mill in the mid 1970s. Spirometry data for the total population by smoking status and age were within the normal range. Prevalence of pleural plaque increased with age, but was lowest in the environmentally exposed group (0.42-12.74%) and greatest in the W.R. Grace & Co. mineworkers (20-45.68%). For males, there was a significant (4.5%) effect of pleural plaques on forced vital capacity. For W.R. Grace & Co. workers and household contacts, a reduction in plaque (0.11 versus 1.64%) and in diffuse pleural thickening or costophrenic angle obliteration (1.94 and 0.13%) was noted for those exposed after 1976. These analyses do not support a clinically important reduction in spirometry of this cohort. The 1976 reductions in exposure have led to decrease in radiographic changes.

Topics: Adult; Aged; Aged, 80 and over; Aluminum Silicates; Asbestos, Amphibole; Cohort Studies; Environmental Exposure; Female; Humans; Lung; Male; Middle Aged; Mining; Montana; Pleural Diseases; Prevalence; Radiography; Respiratory Function Tests; Smoking

Topics: Aluminum Silicates; Asbestos; Dose-Response Relationship, Drug; Humans; Montana; Occupational Exposure; Pleural Diseases; Radiography, Thoracic; Reproducibility of Results; Risk Assessment

Mining, handling, processing, and personal or commercial use of asbestos-contaminated vermiculite have led to widespread contamination of the Libby, Montana, area. We initiated a medical testing program in response to reports of respiratory illness in the community. The purpose of this analysis was to identify and quantify asbestos-related radiographic abnormalities among persons exposed to vermiculite in Libby and to examine associations between these outcomes and participants' self-reported exposures. A cross-sectional interview and medical testing were conducted in Libby from July through November 2000 and from July through September 2001. A total of 7,307 persons who had lived, worked, or played in Libby for at least 6 months before 31 December 1990 completed the interview. Of those, 6,668 participants > or = 18 years of age received chest radiographs to assess the prevalence of pleural and interstitial abnormalities. We observed pleural abnormalities in 17.8% of participants and interstitial abnormalities in < 1% of participants undergoing chest radiography. We examined 29 occupational, recreational, household, and other exposure pathways in the analysis. The prevalence of pleural abnormalities increased with increasing number of exposure pathways, ranging from 6.7% for those who reported no apparent exposures to 34.6% for those who reported > or = 12 pathways. The factors most strongly associated with pleural abnormalities were being a former W.R. Grace worker, being older, having been a household contact of a W.R. Grace worker, and being a male. In addition to being a former W.R. Grace worker, environmental exposures and other nonoccupational risk factors were also important predictors of asbestos-related radiographic abnormalities.

Topics: Adolescent; Adult; Aged; Aluminum Silicates; Asbestos; Child; Cross-Sectional Studies; Female; Humans; Male; Middle Aged; Montana; Occupational Exposure; Pleural Diseases; Radiography, Thoracic; Recreation; Risk Factors; Sex Factors

Chest radiographs taken by a standard technique were obtained from 173 current employees (164 men, 9 women) of a vermiculite mine in Montana, from 80 of 110 past employees resident within 200 miles, and from 47 men from the same area without known exposure to dust. In 43 of the 80 and 24 of the 47 an earlier chest x ray film was retrieved from the hospital archives. All 367 films were assessed blind and independently by three experienced readers using the ILO 1980 classification. Median radiographic assessment scores were analysed in relation to estimated cumulative exposure to the amphibole fibres that contaminate the vermiculite. Logistic regression analyses showed independent effects of age, smoking, and exposure on the prevalence of small opacities and of age and probably of exposure on pleural thickening. Overall, the data suggest that by retirement age the increase in prevalence of small opacities (greater than or equal to 1/0) lies between 5% and 10% per 100 f/ml years. This gradient may be somewhat steeper than for chrysotile miners and millers, but not much so.

Topics: Adult; Age Factors; Aged; Aluminum Silicates; Asbestos, Amphibole; Female; Humans; Lung; Lung Diseases; Male; Middle Aged; Mining; Occupational Diseases; Pleura; Pleural Diseases; Radiography; Silicic Acid; Silicon Dioxide