Oliver Lc

Asbestos-related disease in railroad workers. A cross-sectional study.

A cross-sectional prevalence study of 377 railroad workers was carried out. The purpose was to investigate the prevalence of asbestos-related disease. We compared conventional with more recently adopted criteria for defining abnormal lung function. We compared the test results of those who performed reproducibly on spirometry with those who did not. Medical and occupational histories, flow-volume loops, and posteroanterior and lateral chest radiographs were obtained. Single-breath carbon monoxide diffusing capacity (DLCO) was measured, and chest auscultation was performed. Related to time since onset of exposure, pleural plaques occurred in 22.9%. There was radiographic evidence of interstitial disease in 1.6%. Reduced single-breath DLCO (12.4%), crackles (18.4%), and dyspnea (49.6%) were significantly associated with asbestos exposure. The prevalence of restriction and obstruction was 5.1 and 12.4%, respectively, but differed (p = 0.0001) with the definition criteria selected. The proportion with each of these abnormalities was higher in the nonreproducible group. That group was older, with more pleural plaques and chronic bronchitis. Railroad workers are a group at risk for asbestos-related disease. Extent of disease and assumptions about causality are likely to vary with definitions of normalcy and the use of reproducibility criteria.

Etiology and pathogenesis of hard metal disease

Abstract Workers exposed to cobalt by inhalation are at risk from interstitial lung disease (hard metal disease) and occupational asthma. Exposed groups include tungsten carbide (TC) producers, diamond polishers, grinders and sharpeners of TC tools, and metal coaters using powdered hard metal. Cobalt, the binding agent for TC, is believed to be the casual agent. Information available to date suggests that cobalt in the absence of tungsten or TC can cause interstitial lung disease (ILD) and occupational asthma, while tungsten or TC does not. Questions for further investigation are whether cobalt toxicity is enhanced in the presence of TC or other metals and whether pure cobalt in the absence of any other metals can cause ILD. Prevalence and exposure-response information is available for ILD in workers exposed to cobalt. The prevalence of interstitial lung disease among studies on TC production workers range from 0 to 13%. Because of subject selection for active employed workers, these are probably underestimates of the true prevalence in the industry. Our study of 1039 US TC workers showed that 2.6% had abnormal chest radiographs ( profusion ≥ 1 0 ). We found that the relative odds of an abnormal chest radiograph were increased fivefold when lifetime average cobalt levels exceeded 100 μg/m3, among those with at least 10 years latency. On the other hand, we found three workers with ILD whose exposures had never exceeded 50 μg/m3 and whose latencies where less than 10 years. This study and supporting data from the literature suggests that a subgroup of workers exposed to cobalt is at risk for hard metal disease. Among the subgroup at risk, individual susceptibility to cobalt varies. This may explain why some exposed workers will develop hard metal disease after brief, low cobalt exposures (below the current US standard of 50 μg/m3), while others will develop the disease only after higher cobalt exposures of longer duration.

Screening for Asbestos-Related Pleural Disease with Digital Storage Phosphor Radiography

Digital storage phosphor radiography (SR) has a wide dynamic range and unique postprocessing capabilities that may improve the performance of screening studies for asbestos-related pleural disease compared with conventional film radiography (FR). In a group of 32 asbestos-exposed and nine control subjects with established pleural data, we compared the screening performance of FR and SR obtained with a single isoexposure, dual-energy technique (system resolution 0.2 mm, 10 bits). Performance was evaluated for 7320 observations by eight readers using a paired t test (P less than .02 with Bonferroni correction) of averaged receiver operating characteristic curve (ROC) areas (Az +/- standard error). We found that SR alone and SR supplemented by dual-energy soft-tissue and calcium images (SRde) were superior to FR in the overall detection of pleural abnormalities (Az = 0.90 +/- 0.01, 0.90 +/- 0.01, and 0.88 +/- 0.01, respectively). In the specific detection of pleural calcification, SRde was superior to FR (Az = 0.91 +/- 0.01 and 0.87 +/- 0.01, respectively; P less than 0.01). Analysis of variance indicated that SRde most closely reproduced an established pleural score based on the International Labor Organization (ILO) classification of the pneumoconioses (P less than 0.05, Scheffés multiple comparison test). We conclude that isodose SR performs at least as well as FR in screening for asbestos-related pleural disease. SR supplemented by dual-energy images might improve the specific detection of pleural calcifications compared with FR.