A clinical evaluation and tissue fiber burden analysis of a lifetime resident of Libby, Montana with adenocarcinoma of the lung.

INTRODUCTION: Vermiculite mining operations near Libby, Montana were active from the 1920s to 1990. Rail facilities for shipment of the mined material as well as some vermiculite processing activities were ongoing within the community of Libby. A fibrous component within the mined material has been associated with asbestos-related diseases in vermiculite miners and in the local citizens of the community. CLINICAL HISTORY/METHODS: We present a clinical case history and tissue fiber burden analysis of an individual with a multifocal adenocarcinoma of the lung who was a lifelong resident of Libby and whose history of exposure was as a member of the general population there. RESULTS/DISCUSSION: To our knowledge this is the first time tissue from a member of the general population of Libby, Montana has been evaluated and shown to contain an appreciable presence of "Libby amphibole" fibers.

Autoimmune markers for progression of Libby amphibole lamellar pleural thickening.

Exposure to Libby Asbestiform Amphibole (LAA) is associated with asbestos-related diseases, including mesothelioma, pulmonary carcinoma, pleural fibrosis, and systemic autoimmune diseases. The pleural fibrosis can manifest as a rapidly progressing lamellar pleural thickening (LPT), which causes thoracic pain, dyspnea, and worsening pulmonary function tests (PFT). It is refractory to treatment and frequently fatal.Objective: Because of the immune dysfunction that has been described in the LAA-exposed population and the association of pleural manifestations with the presence of autoantibodies, this study tested whether specific immunological factors were associated with progressive LPT and whether they could be used as markers of progressive disease.Methods: Subjects were placed into three study groups defined as (1) progressive LPT, (2) stable LPT, (3) no LPT. Serum samples were tested for antinuclear autoantibodies, mesothelial cell autoantibodies, anti-plasminogen antibodies, IL1 beta, and IL17; which have all been shown to be elevated in mice and/or humans exposed to LAA.Results: Group 1 had significantly higher mean values for all of the autoantibodies, but not IL1 or IL-17, compared to the control Group 3. All three autoantibody tests had high specificity but low sensitivity, but ROC area-under-the-curve values for all three antibodies were over 0.7, statistically higher than a test with no value. When all LPT subjects were combined (Progressive plus Stable), no marker had predictive value for disease.Conclusion: The data support the hypothesis that progressive LPT is associated with immunological findings that may serve as an initial screen for progressive LPT.

Lung cancer screening in patients with Libby amphibole disease: High yield despite predominantly environmental and household exposure.

BACKGROUND: Lung cancer screening with low-dose computed tomography (CT) scanning (LDCT) is accepted as a screening tool, but its application to populations exposed to recognized occupational or environmental carcinogens is limited. We apply LDCT to a population with a predominantly nonoccupational exposure to a recognized human lung carcinogen, Libby amphibole asbestos (LA). METHODS: Patients in an asbestos disease clinic in Libby, Montana who were aged 50 to 84 years, greater than or equal to 20 pack-year history of tobacco use (irrespective of quit date), and asbestos-related pleuropulmonary disease on high-resolution CT scan were offered free annual lung cancer screening over a 39-month period. RESULTS: Of 2897 clinic patients, 1149 (39.7%) met eligibility criteria, and 567 (49%) were screened with 1014 low-dose CT scans. Most screened patients had principally environmental (333 or 59%) or household exposure (145 or 25%) to LA. Seventeen primary lung cancers were identified, mostly in early stages: 10 at stage 1, two at stage 2, three at stages 3 to 4, and two at limited small-cell cancers. The screening yield was 1.9 at baseline scan and 1.5% on the first annual scan. CONCLUSIONS: Consistent with the guidelines of the National Comprehensive Cancer Network and American Association of Thoracic Surgery, LDCT for early lung cancer detection should be offered to people with significant exposure to occupational or environmental human lung carcinogens.

Case series: rheumatological manifestations attributed to exposure to Libby Asbestiform Amphiboles.

An increased risk for Systemic Autoimmune Diseases (SAID) has been reported in Libby, Montana, where extensive exposures to fibrous amphiboles occurred due to mining and use of asbestos-laden vermiculite. In addition, positive antinuclear autoantibody tests are associated with exposure to Libby Asbestiform Amphiboles (LAA) in both humans and mice. Among 6603 subjects who underwent health screening at the Center for Asbestos Related Diseases (CARD, Libby MT), 13.8% were diagnosed with an autoimmune disease, with prevalence values for the most common SAID being significantly higher than expected in the United States. Among the CARD screening population, serological and clinical profiles are diverse, representing symptoms and autoantibodies reflective of systemic lupus erythematosus (SLE), scleroderma, rheumatoid arthritis, and other rheumatic syndromes, including undifferentiated connective tissue disease (UCTD). Based upon screening of medical records by physicians with rheumatology expertise, the evolving nature of rheumatological disease in these patients is often atypical, with mixed diagnostic criteria and with a 1:1 male-to-female ratio. Through the Libby Epidemiology Research Program, cases were identified that illustrate clinical autoimmune outcomes with LAA exposure. Our goal was to better characterize SAID in Libby, MT in order to improve recognition of autoimmune outcomes associated with this exposure. In view of recent discoveries of widespread exposure to fibrous minerals in several areas of the U.S. and globally, it is critical to evaluate rheumatologic manifestations in other cohorts so that screening, surveillance, and diagnostic procedures are able to detect and recognize potential autoimmune outcomes of asbestos exposure. ABBREVIATIONS: ANA, antinuclear autoantibody; ARD, Asbestos-Related Diseases; ATSDR, Agency for Toxic Substances & Disease Registry; CARD, Center for Asbestos Related Diseases; CCP, Cyclic citrullinated peptide antibody; CREST, limited cutaneous form of scleroderma; CT, computed tomography; DIP, Distal Interphalangeal Joint; DLCO, Diffusing Capacity of the Lung for CO2; DMARD, Disease Modifying Anti-Rheumatic Drugs; ENA, Extractable Nuclear Antigen antibodies; FVC, Forced Vital Capacity; LAA, Libby Asbestiform Amphiboles; LERP, Libby Epidemiology Research Program; MCP, Metacarpal Phalangeal Joint; PIP, Proximal Interphalangeal Joint; PIP, rheumatoid arthritis; RV, Residual Volume; SAID, Systemic autoimmune diseases; SLE, systemic lupus erythematosus; SSc, Systemic Sclerosis; TLC, Total Lung Capacity.

Analysis of autoantibody profiles in two asbestiform fiber exposure cohorts.

An increased risk for Systemic Autoimmune Diseases (SAID) was reported in the population of Libby, Montana, where extensive exposure to asbestiform amphiboles occurred through mining and use of asbestiform fiber-laden vermiculite. High frequencies of antinuclear autoantibodies (ANA) were detected in individuals and mice exposed to Libby Asbestiform Amphiboles (LAA). Among the 6603 individuals who have undergone health screening at the Center for Asbestos Related Diseases (CARD, Libby MT), the frequencies of rheumatoid arthritis, systemic lupus erythematosus, sarcoidosis, and systemic sclerosis are significantly higher than expected prevalence in the United States. While these data support the hypothesis that LAA can trigger autoimmune responses, evidence suggests that chrysotile asbestos does not. Serological testing was therefore performed in subjects exposed to LAA or predominantly chrysotile (New York steamfitters) using multiplexed array technologies. Analyses were performed in order to determine a) autoantibody profiles in each cohort, and b) whether the two populations could be distinguished through predictive modeling. Analysis using perMANOVA testing confirmed a significant difference between autoantibody profiles suggesting differential pathways leading to autoantibody formation. ANA were more frequent in the LAA cohort. Specific autoantibodies more highly expressed with LAA-exposure were to histone, ribosomal P protein, Sm/Ribonucleoproteins, and Jo-1 (histidyl tRNA synthetase). Myositis autoantibodies more highly expressed in the LAA cohort were Jo-1, PM100, NXP2, and Mi2a. Predictive modeling demonstrated that anti-histone antibodies were most predictive for LAA exposure, and anti-Sm was predictive for the steamfitters' exposure. This emphasizes the need to consider fiber types when evaluating risk of SAID with asbestos exposure.

Childhood exposure to Libby amphibole asbestos and respiratory health in young adults.

OBJECTIVES: Vermiculite ore containing Libby amphibole asbestos (LAA) was mined in Libby, MT, from the 1920s-1990. Recreational and residential areas in Libby were contaminated with LAA. This objective of this study was to characterize childhood exposure to LAA and investigate its association with respiratory health during young adulthood. METHODS: Young adults who resided in Libby prior to age 18 completed a health and activity questionnaire, pulmonary function testing, chest x-ray and HRCT scan. LAA exposure was estimated based on participant report of engaging in activities with potential LAA exposure. Quantitative LAA estimates for activities were derived from sampling data and literature reports. RESULTS: A total of 312 participants (mean age 25.1 years) were enrolled and reported respiratory symptoms in the past 12 months including pleuritic chest pain (23%), regular cough (17%), shortness of breath (18%), and wheezing or whistling in the chest (18%). Cumulative LAA exposure was significantly associated with shortness of breath (aOR = 1.12, 95% CI 1.01-1.25 per doubling of exposure). Engaging in recreational activities near Rainy Creek Road (near the former mine site) and the number of instances heating vermiculite ore to make it expand or pop were also significantly associated with respiratory symptoms. LAA exposure was not associated with pulmonary function or pleural or interstitial changes on either chest x-ray or HRCT. CONCLUSIONS: Pleural or interstitial changes on x-ray or HRCT were not observed among this cohort of young adults. However, childhood exposure to LAA was significantly associated with respiratory symptoms during young adulthood. Pleuritic chest pain, in particular, has been identified as an early symptom associated with LAA exposure and therefore warrants continued follow-up given findings of progressive disease in other LAA exposed populations.

Mesothelial cell autoantibodies upregulate transcription factors associated with fibrosis.

Amphibole asbestos exposure is associated with the production of mesothelial cell autoantibodies (MCAA). These MCAA have been linked with pleural fibrotic disease in the asbestos exposed community of Libby, Montana, and induce collagen deposition by cultured mesothelial cells. However, the exact intracellular mechanism by which these autoantibodies cause an increase in collagen deposition remains unknown. This study sought to gain insight into the transcription factors involved in the collagen production after human mesothelial cells are exposed to MCAA. In this study, transcription factor activation profiles were generated from human mesothelial cells (Met5A) treated with serum from Libby subjects, and were compared to cells treated with serum cleared of IgG, and therefore containing no MCAA. Analysis of those profiles indicated C/EBP-beta and hypoxia inducible factor 1 alpha (HIF-1α) are significantly increased in the nucleus, indicating activation, due to MCAA exposure compared to controls. Inhibition of either of these transcription factors significantly reduced collagen 1 deposition by these cells following exposure to MCAA. These data suggest autoantibodies are directly involved in type I collagen deposition and may elucidate potential therapeutic targets for autoantibody mediated fibrosis.

A clinical assessment and lung tissue burden from an individual who worked as a Libby vermiculite miner.

During its days of operation (1920s-1990), the world's largest source of vermiculite was extracted from a mine located near Libby, Montana. The material mined at this site was shipped for various commercial applications to numerous sites in the United States. There was a "fibrous" component with toxic potential within the vermiculite deposit that has resulted in "asbestos-like" diseases/deaths being reported in numerous studies involving miners as well as residents of the town of Libby. The present case involves the clinical assessments of an individual who worked at the mine from 1969 to 1990. He had no other known occupational exposures to fibrous materials. He developed a clinical picture that included "asbestos-like" pathological features and eventually an adenocarcinoma. The clinical assessment including radiographic features will be presented. The evaluation will also include the analytical evaluation of the fibrous/ferruginous body composition of the lung tissue. This is to our knowledge the first time such an extensive evaluation has been conducted in a vermiculite miner from Libby, Montana.

Pulmonary abnormalities as a result of exposure to Libby amphibole during childhood and adolescence-The Pre-Adult Latency Study (PALS).

BACKGROUND: The purpose of Pre-Adult Latency Study was to evaluate lung findings among adults who had been environmentally exposed to Libby Amphibole only during childhood and adolescence. METHODS: Recruitment was restricted to volunteers who attended primary and/or secondary school, lived in Libby, MT, prior to age 23 years for males and 21 years for females and subsequently left the area. Subjects completed exposure and respiratory questionnaires, underwent pulmonary function tests (PFTs), and chest CT scans. A Pleural Score was calculated for degree and extent of pleural thickening. Logistic regression and multivariate linear regression were used. RESULTS: Of the 219 who met inclusion criteria, 198 participated. Pleural thickening was found in 96 (48%) of 198 participants. In almost half of these, it was of the lamellar type, not generally seen in exposure to other asbestos. Environmental Libby amphibole exposure was associated with pleural thickening, and the likelihood of pleural thickening increased with the number of years lived in the area. An inverse association between Pleural Score and PFT was found, which remained significant for FVC and DLco after additional sensitivity analyses. CONCLUSIONS: Cumulative environmental exposure was associated with risk of pleural thickening. Among this cohort, quantitative measures of pleural thickening were associated with decreased PFT. Am. J. Ind. Med. 60:20-34, 2017. © 2016 Wiley Periodicals, Inc.

Social Support Functions During a Slowly-Evolving Environmental Disaster: The Case of Amphibole Asbestos Exposure in Libby, Montana.

Previous research concluded that victims of rapid-onset natural disasters (e.g., hurricanes) receive and provide high levels of instrumental support. However, different kinds of disasters (natural or human caused [technological, environmental, intentional/terrorism], rapid or slow onset, short or long duration) may create different stressors and thus influence the types of social support most needed and provided. We explored social support functions during an ongoing "slowly-evolving environmental disaster" in Libby, Montana due to widespread exposure to amphibole asbestos. Analyses of focus groups and in-depth interviews focused on the relative salience of support functions (emotional, informational, instrumental, and spiritual) identified as needed or provided. Dominant themes emerged around each function. Results indicated that informational support is particularly salient in this type of disaster. Although not all community members had experienced the disaster's health consequences (asbestos-related disease [ARD]), all had been affected by the disaster and had informational needs. The nature of those informational needs (e.g., medical vs. financial) varied based on experience with ARD. Experience with ARD was associated with awareness of disaster-related emotional and instrumental support needed or provided. Results have implications for future research on slowly-evolving environmental disasters and institutional and community responses to them.

Asbestos-associated mesothelial cell autoantibodies promote collagen deposition in vitro.

Fibrosis, characterized by excessive collagen protein deposition, is a progressive disease that can fatally inhibit organ function. Prolonged exposure to pathogens or environmental toxicants such as asbestos can lead to chronic inflammatory responses associated with fibrosis. Significant exposure to amphibole asbestos has been reported in and around Libby, Montana due to local mining of asbestos-contaminated vermiculite. These exposures have been implicated in a unique disease etiology characterized predominantly by pleural disorders, including fibrosis. We recently reported the discovery of mesothelial cell autoantibodies (MCAAs) in the sera of Libby residents and demonstrated a positive and significant correlation with pleural disease; however, a mechanistic link was not determined. Here we demonstrate that MCAAs induce pleural mesothelial cells to produce a collagen matrix but do not affect production of the pro-inflammatory cytokine tumor growth factor-ß. While autoantibodies commonly induce a pro-fibrotic state by inducing epithelial-mesenchymal transition (EMT) of target cells, we found no evidence supporting EMT in cells exposed to MCAA positive human sera. Although implicated in other models of pulmonary fibrosis, activity of the protein SPARC (secreted protein, acidic and rich in cysteine) did not affect MCAA-induced collagen deposition. However, matrix formation was dependent on matrix metalloproteinase (MMP) activity, and we noted increased expression of MMP-8 and -9 in supernatants of mesothelial cells incubated with MCAA positive sera compared to control. These data suggest a mechanism by which MCAA binding leads to increased collagen deposition through altering MMP expression and provides an important mechanistic link between MCAAs and asbestos-related, autoimmune-induced pleural fibrosis.

Non-neoplastic and neoplastic pleural endpoints following fiber exposure.

Exposure to asbestos fibers is associated with non-neoplastic pleural diseases including plaques, fibrosis, and benign effusions, as well as with diffuse malignant pleural mesothelioma. Translocation and retention of fibers are fundamental processes in understanding the interactions between the dose and dimensions of fibers retained at this anatomic site and the subsequent pathological reactions. The initial interaction of fibers with target cells in the pleura has been studied in cellular models in vitro and in experimental studies in vivo. The proposed biological mechanisms responsible for non-neoplastic and neoplastic pleural diseases and the physical and chemical properties of asbestos fibers relevant to these mechanisms are critically reviewed. Understanding mechanisms of asbestos fiber toxicity may help us anticipate the problems from future exposures both to asbestos and to novel fibrous materials such as nanotubes. Gaps in our understanding have been outlined as guides for future research.

Rural public health policy models to address an evolving environmental asbestos disaster.

The health-related dangers of asbestos exposure were recognized early in the 20th century when occupational exposure was found to be associated with excess pneumoconiosis among asbestos industry workers. Today, the epicenter for examining the public health effects and the human toll that this toxin has had on a population is located in the rural community of Libby, MT. Rurality and multideterminants of health frame both the history of asbestos-related disease and the service/policy challenges within a community dealing with chronic illness and designation as a Superfund clean-up site. Despite efforts by public health advocates to address the lingering aftermath of an environmental disaster in this community, policy gaps exist that continue to impact the population's health. The purpose of this paper is to describe the history and outcomes of asbestos exposure in a rural community and discuss 3 models that provide public health policy insights related to rural health and health care for a community affected by both a sentinel and ongoing environmental event.

Libby Amphibole Disease: Pulmonary Function and CT Abnormalities in Vermiculite Miners.

OBJECTIVE: 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). METHODS: Individuals who worked at the mine for a minimum of 6 months had chest CT and pulmonary function tests. RESULTS: 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. CONCLUSION: 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.

Libby amphibole-induced mesothelial cell autoantibodies bind to surface plasminogen and alter collagen matrix remodeling.

Lamellar pleural thickening (LPT) is a fibrotic disease induced by exposure to Libby amphibole (LA) asbestos that causes widespread scarring around the lung, resulting in deterioration of pulmonary function. Investigating the effects of autoantibodies to mesothelial cells (MCAA) present in the study populations has been a major part of the effort to understand the mechanism of pathogenesis. It has been shown in vitro that human mesothelial cells (Met5a) exposed to MCAA increase collagen deposition into the extracellular matrix (ECM). In this study, we sought to further elucidate how MCAA drive increased collagen deposition by identifying the protein targets bound by MCAA on the cellular surface using biotinylation to label and isolate surface proteins. Isolated surface protein fractions were identified as containing MCAA targets using ELISA The fractions that demonstrated binding by MCAA were then analyzed by tandem mass spectrometry (MS/MS) and MASCOT analysis. The most promising result from the MASCOT analysis, plasminogen (PLG), was tested for MCAA binding using purified human PLG in an ELISA We report that serum containing MCAA bound at an optical density (OD) 3 times greater than that of controls, and LA-exposed subjects had a high frequency of positive tests for anti-PLG autoantibodies. This work implicates the involvement of the plasminogen/plasmin system in the mechanism of excess collagen deposition in Met5a cells exposed to MCAA Elucidating this mechanism could contribute to the understanding of LPT.

Principal components analysis to identify influences on research communication and engagement during an environmental disaster.

OBJECTIVES: To discern community attitudes towards research engagement in Libby, Montana, the only Superfund site for which a public health emergency has been declared. STUDY DESIGN: Survey study of convenience samples of residents near the Libby, Montana Superfund site. PARTICIPANTS: Residents of the Libby, Montana area were recruited from a local retail establishment (N=120, survey 1) or a community event (N=127, survey 2). MEASURES: Two surveys were developed in consultation with a Community Advisory Panel. RESULTS: Principal components of survey 1 showed four dimensions of community members' attitudes towards research engagement: (1) researcher communication and contributions to the community, (2) identity and affiliation of the researchers requesting participation, (3) potential personal barriers, including data confidentiality, painful or invasive procedures and effects on health insurance and (4) research benefits for the community, oneself or family. The score on the first factor was positively related to desire to participate in research (r=0.31, p=0.01). Scores on factors 2 and 3 were higher for those with diagnosis of asbestos-related disease (ARD) in the family (Cohen's d=0.41, 0.57). Survey 2 also found more positive attitudes towards research when a family member had ARD (Cohen's d=0.48). CONCLUSIONS: Principal components analysis shows different dimensions of attitudes towards research engagement. The different dimensions are related to community members' desire to be invited to participate in research, awareness of past research in the community and having been screened or diagnosed with a health condition related to the Superfund contaminant.

Childhood exposure to Libby amphibole during outdoor activities.

Residents of Libby, MT were exposed to amphibole asbestos through multiple environmental pathways. Previous exposure characterization has primarily relied on qualitative report of these exposure activities. The objectives of this study were to describe available data from the US EPA preremediation actions for Libby amphibole (LA) exposure in Libby, MT and develop an approach to characterize outdoor residential exposure to LA among children. Homes in Libby, MT included in the US EPA preremediation Contaminant Screening Survey (CSS) were categorized by the presence of interior and/or exterior visible vermiculite and concentrations of LA were measured in samples of dust and soil. Airborne exposure to LA while digging/gardening, raking, and mowing were estimated using US EPA activity-based sampling (ABS) results. Residential histories and frequency/duration of childhood activities were combined with ABS to demonstrate the approach for estimating potential exposure. A total of 3154 residential properties participated in the CSS and 44% of these had visible exterior vermiculite. Airborne concentrations of LA where there was visible vermiculite outdoors were 3-15 times higher during digging/gardening, raking, and mowing activities compared with homes without visible outdoor vermiculite. Digging and gardening activities represented the greatest contribution to estimated exposures and 73% of the participants reported this activity before the age of 6 years. This methodology demonstrated the use of historical preremediation data to estimate residential exposures of children for specific activities. Children younger than age 6 years may have been exposed to LA while digging/gardening, especially at homes where there is visible outdoor vermiculite. This approach may be extended to other activities and applied to the entire cohort to examine health outcomes.

Multiple pathway asbestos exposure assessment for a Superfund community.

Libby, MT, USA, was the home to workers at a historical vermiculite mining facility and served as the processing and distribution center for this industrial product that was contaminated with amphibole asbestos. Several pathways of environmental asbestos exposure to the general population have been identified. The local clinic and health screening program collects data from participants on past occupational and environmental exposures to vermiculite and asbestos. Health studies among this population have demonstrated associations between amphibole exposure and health outcomes, but critical questions regarding the nature and level of exposure associated with specific outcomes remain unanswered. The objective of this study was to develop a comprehensive exposure assessment approach that integrates information on individuals' contact frequency with multiple exposure pathways. For 3031 participants, we describe cumulative exposure metrics for environmental exposures, occupational exposures, and residents' contact with carry-home asbestos from household workers. As expected, cumulative exposures for all three occupational categories were higher among men compared with women, and cumulative exposures for household contact and environmental pathways were higher among women. The comprehensive exposure assessment strategies will advance health studies and risk assessment approaches in this population with a complex history of both occupational and environmental asbestos exposure.

Radiographic abnormalities and exposure to asbestos-contaminated vermiculite in the community of Libby, Montana, USA.

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.

Descriptive analysis of the respiratory health status of persons exposed to Libby amphibole asbestos.

OBJECTIVE: Describe respiratory health and quality of life in persons exposed to Libby amphibole asbestos (LAA) contaminated vermiculite. DESIGN: Cross-sectional descriptive. SETTING: Asbestos-related disease clinic in Libby, Montana USA. PARTICIPANTS: 329 individuals exposed to LAA; mostly men, married, between 50 and 69 years; two-thirds lived in the surrounding county; one-third lived elsewhere in the state and USA. PRIMARY OUTCOME MEASURES: Chest radiograph (CXR), pulmonary function data and the St George Respiratory Questionnaire (SGRQ). RESULTS: Exposure categories included vermiculite workers=7.6%; family/household contact of vermiculite worker=32%; and environmental exposure only=60%. Of the participants, 55% had only pleural abnormalities; 5.4% had only interstitial abnormalities; nearly 21% had both abnormalities and 18% had no lung abnormality on chest x-ray. Mean forced vital capacity (FVC) 95.3% (SD=18.7); forced expiratory volume (FEV(1)) mean 87% (SD=20.2); ratio of FEV1(1)/FVC 95.5% (SD=12.0); and diffusing capacity (DLCO) of 83% (SD=21.7) of the percent predicted. The mean total SGRQ (38.5; SD=22.1) indicated a lower quality of life than healthy persons and persons with other chronic conditions. SGRQ subscale means were Symptoms 52.1 (SD=24.9), activity 49.4 (SD=26.9) and impacts 27.5 (SD=21.9). Participants with normal CXR differed significantly from those with both interstitial and pleural abnormalities on total, activity and impacts scores. For activity alone, subjects with normal CXR differed significantly from those with pleural disease; no differences were found for those with interstitial disease. Significant findings were found for smoking history across all pulmonary measures, and for exposure status, radiographic findings, age and gender for select pulmonary parameters. Subjects with any smoking history had significantly worse average total and subscale scores on the SGRQ. CONCLUSIONS: Of 329 persons exposed to LAA, the majority (182) had pleural abnormalities identified on CXR. SGRQ scores for persons with abnormalities (pleural, interstitial or both) (269) differed significantly from those with a normal CXR.