Exposure‒response relationships for silicosis and its progression in industrial sand workers.

Objectives This study aimed to characterize the relationship between radiographic silicosis and exposure to respirable quartz and determine how exposure affects disease progression. Methods Surveillance chest radiographs from a cohort of 1902 workers were examined to identify 67 cases of radiographic silicosis and 167 matched controls. Exposures were estimated by linking work histories to a job exposure matrix (JEM) based on samples collected by the participating companies and historical estimates. Conditional logistic regression was used to examine exposure‒response relationships. Sequential radiographs from silicosis cases were used to assess associations between exposure and disease progression. Results Risk of silicosis increased with cumulative exposure [odds ratio (OR) 1.43 per 1 mg/m 3years, 95% confidence interval (CI) 1.23-1.66], average exposure concentration (OR 1.30 per 0.10 mg/m 3, 95% CI 1.11-1.51) and net exposure duration (OR 1.10 per year, 95% CI 1.05-1.16). Multivariate analyses indicated that the risk associated with cumulative exposure varied depending on exposure duration and concentration. Analysis of the time worked at differing exposure levels indicated that exposures ≤0.05 mg/m 3were not significantly associated with silicosis risk after adjustment for years worked at higher concentrations. Disease progression was related to subsequent exposure concentration, with a yearly increase in small opacity profusion of 0.052 subcategory per each 0.10 mg/m 3increase in concentration. Conclusions Workers with longer exposure at lower concentrations were at higher risk for silicosis than those with the same cumulative exposure who worked for a shorter time at higher concentrations. The rate of silicosis progression was related to subsequent exposure concentration.

Aggressive and atypical manifestations of Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a disseminated non-Langerhans' cell histiocytosis with multisystem involvement, including characteristic sclerotic musculoskeletal lesions. We present the case of a 27-year-old woman with a fulminant course and atypical involvement by ECD manifesting as extensive cerebrovascular disease and lytic musculoskeletal lesions. This case represents an unusual and aggressive presentation of ECD owing to the patient's young age, the severity of the cerebrovascular involvement and the lytic osseous lesions.

International Labor Office Classification System in the age of imaging: relevant or redundant.

The 1980 International Labor Office International Classification of Radiographs of Pneumoconioses is a widely used epidemiologic tool with a storied past. This article reviews its development and examines its applications to occupational lung disease and the controversies generated in that process. The question of its relevancy to current imaging practices is discussed.

Reliability of the proposed international classification of high-resolution computed tomography for occupational and environmental respiratory diseases.

PURPOSE: We have developed a classification of high-resolution computed tomography (HRCT) images for screening, surveillance and epidemiological studies of respiratory diseases caused by occupational and environmental factors. The proposed classification consists of three parts: a guideline explaining the elements of the classification scheme, a reading sheet, and reference films to aid in assessing thin-section CT films. We assessed the reliability of the proposed classification system by blinded, independent trial reading. MATERIALS AND METHODS: Seven independent radiologists and pulmonologists performed a trial reading to measure the reliability of the classification system using HRCT films from 27 pneumoconiosis patients and 7 normal controls. RESULTS: The agreement was moderate to good for rounded opacities (weighted kappa=0.68 and 0.64), irregular opacities (0.59, 0.48), honeycombing (0.65, 0.47), emphysema (0.76, 0.62) and large opacities (0.48, 0.52). Ground glass opacities (0.16, 0.20) showed poor to fair agreement. Intra-reader agreement of each of the seven readers was moderate to good (mean: weighted kappa=0.52-0.80) for parenchymal findings, but the agreement was relatively low (mean weighted kappa=0.52) for ground glass opacities. CONCLUSION: The proposed classification is able to describe early dust-related fibrotic changes and provide a semi-quantitative description of the HRCT features of major fibrotic changes in the parenchyma and pleura. Reliability, as measured by inter-reader agreement, was satisfactory.