International Labour Office Classification Research Articles

Silicosis.

I was pleased to see the emphasis on silicosis in your recent issue, but sad that the lessons my generation has learned over the past six decades have had so little impact worldwide on prevention. These lessons are: Silicosis presents a variety of radiological appearances, depending on the intensity and duration of exposure and the mineral content of the dust. There is only one useful test for surveillance—chest radiography. Symptoms and pulmonary impairment only come late in the evolution of the disease. In this context, ‘late’ does not mean duration of exposure, since very heavy exposure to freshly generated silica can cause death within a year. The International Labour Office (ILO) classification of radiographs was not intended for diagnosis but for epidemiological purposes, to reduce the inevitable variation between x-ray readers. Rather, it allows description of the changes seen in relation to standard ‘normal’ films. Diagnosis in individuals depends also on taking account of clinical factors, notably exposure to, and type of, dust.

What does coal mine dust lung disease look like? A radiological review following re-identification in Queensland.

Coal mine dust lung disease (CMDLD), including the pneumoconioses, dust-related diffuse fibrosis (DDF) and chronic obstructive pulmonary disease (COPD), are occupational lung diseases attributed to respirable coal mine dust. Following the re-identification of CMDLD in Queensland in 2015, we undertook a case series to understand their radiological presentation. Chest radiographs and high-resolution computed tomography (HRCT) were retrospectively reviewed for 79 male individuals diagnosed by a respiratory physician with a CMDLD since 2015. Radiological findings were characterised as per the International Labour Office Classification System(ILO system) and the International Classification of HRCT for Occupational and Environmental Respiratory Diseases (ICOERD). Subjects with pneumoconiosis (n=56) demonstrated widespread opacities with bilateral upper zone predominance. The majority of the lung was impacted, with 72% and 79% of zones demonstrating opacities on chest radiograph and HRCT, respectively. Most pneumoconiosis subjects (71%) demonstrated ILO category 1 disease, while 29% had advanced disease (ILO grades≥2/1). A high proportion (81%) of pneumoconiosis subjects demonstrated at least one radiological feature associated with exposure to respirable crystalline silica (RCS). DDF subjects (n=5) had radiologically severe disease (mean ILO 2/1) with lower zone-predominant irregular opacities. Widespread emphysema, with no zone dominance, was the key radiological feature in those with COPD (n=18). Radiological findings of particular interest included the high burden of opacities observed and the presence of RCS-associated features in the majority of subjects. Radiologists are at the front line in occupational lung disease screening/diagnosis and must be aware of the imaging spectrum.

Longitudinal decline in lung function among older construction workers

BackgroundOccupational exposures to vapours, gasses, dusts and fumes (VGDF) and chest X-ray abnormalities by the International Labour Office (ILO) classification system are associated with reduced lung function, with the majority...

Pneumoconioses Radiographs in a Large Population of U.S. Coal Workers: Variability in A Reader and B Reader Classifications by Using the International Labour Office Classification.

Purpose To assess the level of concordance between chest radiographic classifications of A and B Readers in a national surveillance program offered to U.S. coal miners over an approximate 36-year period. Materials and Methods The National Institute for Occupational Safety and Health (NIOSH) Coal Workers' Health Surveillance Program (CWHSP) is a surveillance program with nonresearch designation and is exempt from Human Subjects Review Board approval (11-DRDS-NR03). Thirty-six years of data (1979-2015) from the CWHSP were analyzed, which included all conventional screen-film radiographs with a classification by at least one A Reader and one B Reader. Agreement was assessed by using κ statistics; prevalence ratios were used to describe differences between A and B Reader determinations of image technical quality, small opacity profusion, and presence of large opacities and pleural abnormalities. Results The analysis included 79 185 matched A and B Reader chest radiograph classifications. A majority of both A and B Readers were radiologists (74.2% [213 of 287] vs 64.7% [22 of 34]; P = .04). A and B Readers had minimal agreement on technical image quality (κ = 0.0796; 95% confidence interval [CI]: 0.07, 0.08) and the distribution of small opacity profusion (subcategory κ, 0.2352; 95% CI: 0.22, 0.25). A Readers classified more images as "good" quality (prevalence ratio, 1.38; 95% CI: 1.35, 1.41) and identified more pneumoconiosis (prevalence ratio, 1.22; 95% CI: 1.20, 1.23). Conclusion A Readers classified substantially more radiographs with evidence of pneumoconiosis and classified higher small opacity profusion compared with B Readers. These observations reinforce the importance of multiple classifications by readers who have demonstrated ongoing competence in the International Labour Office classification system to ensure accurate radiographic classifications. © RSNA, 2017.

Coal mine dust lung disease in the modern era.

Coal workers' pneumoconiosis (CWP), as part of the spectrum of coal mine dust lung disease (CMDLD), is a preventable but incurable lung disease that can be complicated by respiratory failure and death. Recent increases in coal production from the financial incentive of economic growth lead to higher respirable coal and quartz dust levels, often associated with mechanization of longwall coal mining. In Australia, the observed increase in the number of new CWP diagnoses since the year 2000 has necessitated a review of recommended respirable dust exposure limits, where exposure limits and monitoring protocols should ideally be standardized. Evidence that considers the regulation of engineering dust controls in the mines is lacking even in high-income countries, despite this being the primary preventative measure. Also, it is a global public health priority for at-risk miners to be systemically screened to detect early changes of CWP and to include confirmed patients within a central registry; a task limited by financial constraints in less developed countries. Characteristic X-ray changes are usually categorized using the International Labour Office classification, although future evaluation by low-dose HRCT) chest scanning may allow for CWP detection and thus avoidance of further exposure, at an earlier stage. Preclinical animal and human organoid-based models are required to explore potential re-purposing of anti-fibrotic and related agents with potential efficacy. Epidemiological patterns and the assessment of molecular and genetic biomarkers may further enhance our capacity to identify susceptible individuals to the inhalation of coal dust in the modern era.

Evaluation of bone mineral density and 25-hydroxyvitamin D levels in subjects with silica exposure.

The purpose of the study was to evaluate the bone mineral density (BMD) and 25-hydroxyvitamin D (25(OH)D) levels in patients with silica exposure. The study included 104 male subjects with silica exposure and 36 healthy subjects. Posterior-anterior radiographs were classified according to the International Labour Office (ILO) Classification. Category 0 patients were classified as Group I (n = 54), category I patients were classified as Group II (n = 25), Category II and III patients were classified as Group III (n = 25). Femoral neck BMD values were significantly lower in Group III (p = 0.007). Lumbar vertebrae BMD values were significantly lower in all groups with silica exposure than in the control group (p = 0.000). The osteoporosis rate was significantly higher in Group III (p = 0.000). Subjects with silica exposure were determined to have diminished 25(OH)D levels (p = 0.012). The results of this study demonstrated that subjects with silica exposure have diminished BMD and 25(OH)D levels.

Recognize and classify pneumoconiosis

In the year 2012, out of the 10 most frequently recognized occupational diseases 6 were forms of pneumoconiosis. With respect to healthcare and economic aspects, silicosis and asbestos-associated diseases are of foremost importance. The latter are to be found everywhere and are not restricted to large industrial areas. Radiology has a central role in the diagnosis and evaluation of occupational lung disorders. In cases of known exposure mainly to asbestos and quartz, the diagnosis of pneumoconiosis, with few exceptions will be established primarily by the radiological findings. As these disorders are asymptomatic for a long time they are quite often detected as incidental findings in examinations for other reasons. Therefore, radiologists have to be familiar with the pattern of findings of the most frequent forms of pneumoconiosis and the differential diagnoses. For reasons of equal treatment of the insured a quality-based, standardized performance, documentation and evaluation of radiological examinations is required in preventive procedures and evaluations. Above all, a standardized low-dose protocol has to be used in computed tomography (CT) examinations, although individualized concerning the dose, in order to keep radiation exposure as low as possible for the patient. The International Labour Office (ILO) classification for the coding of chest X-rays and the international classification of occupational and environmental respiratory diseases (ICOERD) classification used since 2004 for CT examinations meet the requirements of the insured and the occupational insurance associations as a means of reproducible and comparable data for decision-making.

Talcosis in soapstone artisans: High-resolution CT findings in 12 patients

To describe the high-resolution computed tomography (HRCT) features of pneumoconiosis observed in soapstone artisans. The present study included 12 soapstone artisans with chest radiography abnormalities consistent with the diagnosis of pneumoconiosis, in accordance with the International Labour Office classification. All patients had undergone HRCT, and the images were retrospectively analysed by two chest radiologists, who reached decisions in consensus. All patients presented with interlobular septal thickening. Small centrilobular nodules (75%) and ground-glass opacities (67%) were also common findings. The distributions of abnormalities were predominantly diffuse. No pleural abnormality was found. The HRCT abnormalities observed in this group of soapstone artisans are similar to those of pure talc pneumoconiosis.

Spiroergometric parameters at maximal exercise testing assessed functional respiratory impairment in asbestos‐induced fibrosis

Exercise intolerance is typical for asbestosis. We examined the correlation of spiroergometric parameters with severity of asbestosis according to the International Labour Office (ILO) classification. Patients were compared to a healthy control group. Nineteen consecutive male patients with compensated asbestosis and 24 healthy subjects were examined. All participants underwent pulmonary functional testing including maximal cardiopulmonary exercise testing (CPET). Results were compared to those of healthy subjects; the correlation to disease status was investigated. Significantly lower VCin , FVC, FEV1 , MEF50 , TLC and PaO2 at rest (P<0.001) were observed in asbestosis patients. Lower peak (weight-related) work rate (WR, WR/kg), (weight-related) oxygen uptake (V'O2 , V'O2 /kg), oxygen pulse (V'O2 /hr), ventilation volume (V'E ), carbon dioxide output (V'CO2 ) and blood lactate was associated (P<0.001) with more severe asbestosis according to the ILO-classification. Significant positive correlations (P<0.001) were seen for alveolar-arterial oxygen difference [P(A-a)O2 ] and PaCO2 . Multiple regression analysis revealed that asbestosis was the only significant factor associated with the spiroergometric parameters (P<0.001). A reduction of V'O2 , V'O2 /kg, V'O2 /hr, V'E , or V'CO2 at identical submaximal workload could neither be detected among the asbestosis severity nor in comparison to healthy subjects. Only the respiratory frequency was depending on severity of asbestosis. The severity of asbestosis correlates with maximal WR, V'O2 , V'O2 /hr, V'E and gas exchange. At identical workload the discrimination between patients and controls was only possible concerning the respiratory frequency. For detection of limitations in asbestosis patients, maximal CPET is recommended.

Lung-Function Impairment Among US Underground Coal Miners, 2005 to 2009

To investigate contemporary geographic distributions of lung-function impairment and radiographic evidence of coal workers' pneumoconiosis (CWP) and their associations. From 2005 to 2009, 6373 underground coal miners completed a health survey, including spirometry testing and chest radiography. Coal workers' pneumoconiosis and progressive massive fibrosis were determined by NIOSH B readers, using the International Labour Office classification. Prevalences of CWP and spirometry less than lower normal limits were mapped by county, and their association assessed. The prevalences of abnormal spirometry results and CWP were 13.1% and 4.0%, respectively. Counties with elevated prevalences for both the outcomes were located in contiguous areas of southeastern Kentucky, western Virginia, southern West Virginia, and eastern Pennsylvania. Prevalence of abnormal spirometry results increases with increasing category of simple CWP and progressive massive fibrosis. Abnormal spirometry in coal miners is associated with CWP; these two health outcomes have similar geographic distributions.

Small pneumoconiotic opacities on U.S. coal worker surveillance chest radiographs are not predominantly in the upper lung zones

Radiographic shadows of coal workers' pneumoconiosis (CWP) are commonly described as predominantly in the upper lung zones. We evaluated the lung distribution of small opacities on surveillance chest radiographs (CXRs) taken between 1981 and 2010 among 2,467 underground US coal miners. All had evidence of pneumoconiosis (category ≥1/0), based on the contemporary International Labour Office Classification of Radiographs of Pneumoconioses. Small opacity involvement was approximately equal over all lung zones, with 30.7% of the total involvement reported in the upper zones, 37.1% in the middle zones, and 32.1% in the lower zones. Primarily rounded opacities were seen in 62.1% of miners and primarily irregular opacities were seen in 37.9%. Miners with primarily rounded opacities had a distribution with moderate upper zone predominance (upper = 36.8%, middle = 36.5%, and lower = 27.2%). In contrast, miners with primarily irregular opacities showed a lower zone preponderance (upper = 20.5%, middle = 38.4%, and lower = 41.1%). The distribution of small pneumoconiotic opacities on surveillance CXRs of working US coal miners is not consistent with the conventional expectations of upper lung zone predominance.

The association between tobacco burden and “dirty chest” is unlikely to follow a linear dose-response pattern

The association between tobacco burden and “dirty chest” is unlikely to follow a linear dose-response pattern

Intramodality and Intermodality Comparisons of Storage Phosphor Computed Radiography and Conventional Film-Screen Radiography in the Recognition of Small Pneumoconiotic Opacities

Digital radiography systems are replacing traditional film for chest radiographic monitoring in the recognition of pneumoconiosis. To further investigate previous findings regarding the equivalence of film-screen radiographs (FSRs) and storage phosphor computed radiographs (CRs), FSRs and CRs from 172 underground coal miners were classified independently by seven National Institute for Occupational Safety and Health-approved B readers, using the International Labor Office (ILO) classification of radiographs of pneumoconiosis. More CRs were classified as "good" quality compared with FSRs (prevalence ratio [PR], 1.5; 95% CI, 1.4-1.6; P , .001). B readers showed good overall agreement on scoring small opacity profusion using CRs vs FSRs (weighted κ, 0.58; 95% CI, 0.54-0.62). Significantly more irregular opacities (compared with rounded) were classified using CR images compared with FSR (PR, 1.3; 95% CI, 1.1-1.6; P = .01). Similarly, the smallest sized opacities (width < 1.5 mm, p and s type) were reported more frequently using CR vs FSR images (PR, 1.3; 95% CI, 1.1-1.5; P < .001). Interreader and intrareader agreement was lower with respect to the classification of shape and size than for small opacity profusion. Overall, interreader and intrareader variability did not differ significantly using CR vs FSR. Under optimal conditions, using standardized methods and equipment, reader visualization of small pneumoconiotic opacities does not appear to differ meaningfully, whether using CR or FSR. Variability in ILO classifications between imaging modalities appears to be considerably lower than variability among readers. The well-documented challenge of reader variability does not appear to be resolved through the use of digital imaging alone, and additional approaches must be evaluated.

Absence of radiographic asbestosis and the risk of lung cancer among asbestos‐cement workers: Extended follow‐up of a cohort

It has been a matter of controversy whether there is an increased risk of lung cancer among asbestos-exposed workers without radiographic asbestosis. A previous study of lung cancer risk among asbestos-cement workers has been updated with an additional 12 years of follow-up. Subjects had received radiographic examination at 20 and 25 years from first exposure to asbestos. Radiographs were interpreted by a single National Institute of Safety and Health (NIOSH)-certified B-reader using the 1971 International Labor Office (ILO) Classification of the pneumoconioses as reference standard. Asbestosis was defined as an ILO coding of 1/0 or higher. Standardized Mortality Ratios (SMRs) were calculated using the general population of Ontario as reference. Among asbestos-cement workers without radiographic asbestosis at 20 years latency the lung cancer SMR was 3.84 (2.24-6.14). Among workers without asbestosis when examined at 25 years latency the SMR was 3.69 (1.59-7.26). Workers from an Ontario asbestos-cement factory who did not have radiographic asbestosis at 20 or 25 years from first exposure to asbestos continued to have an increased risk of death from lung cancer during an additional 12 years of follow-up.

Comparison of storage phosphor computed radiography with conventional film-screen radiography in the recognition of pneumoconiosis

Traditional film-screen radiography (FSR) has been useful in the recognition and evaluation of interstitial lung diseases, but is becoming increasingly obsolete. To evaluate the applicability of storage phosphor digital computed radiography (CR) images in the recognition of small lung opacities, we compared image quality and the profusion of small opacities between FSR and CR radiographs. We screened 1,388 working coal miners during the course of the study with FSR and CR images obtained on the same day from all participants. Each traditional chest film was independently interpreted by two of eight experienced readers using the International Labour Office (ILO) classification of radiographs of pneumoconiosis, as were CR images displayed on medical-grade computer monitors. The prevalence of small opacities (ILO category 1/0 or greater) did not differ between the two imaging modalities (5.2% for FSR and 4.8% for soft copy CR; p>0.50). Inter-reader agreement was also similar between FSR and CR. Significant differences between image modalities were observed in the shape of small opacities, and in the proportion of miners demonstrating high opacity profusion (category 2/1 and above). Our results indicate that, with appropriate attention to image acquisition and soft copy display, CR digital radiography can be equivalent to FSR in the identification of small interstitial lung opacities.

Interobserver Variations in Diagnosing Asbestosis According to the ILO Classification

Inhalation of asbestos fibres leads to asbestosis of the pleura and the lung, with possible progression to lung cancer and malignant pleural or peritoneal mesothelioma. Asbestosis remains difficult to diagnose, especially in its early stages. The most important role in its diagnosis is that of chest radiographs. The aim of this cross-sectional study was to address interobserver variations in interpreting chest radiographs in asbestos workers, which remain to be an issue, despite improvements in the International Labour Office (ILO) classification system. In our ten-year study, we investigated 318 workers occupationally exposed to asbestos, and in 210 workers with diagnosed asbestos-related changes we compared interpretations of chest radiographs according to ILO by two independent radiologists. The apparent degree of interobserver variation in classifying lung fibrosis was 26.66% for the diameter of changes and 42.2% for the profusion of the changes. In cases with diffuse pleural thickening, the interobserver variation using ILO procedures was 34.93%. This investigation raises the issue of standardisation and objectivity of interpretation of asbestosis according to the ILO classification system. This study has revealed a significant disagreement in the estimated degree of pleural and parenchymal asbestos pulmonary disease. This is why we believe high-resolution computed tomography (HRCT) should also be used as a part of international classification.

An epidemic of silicosis among former denim sandblasters

Sandblasting denim using silica has emerged as a new cause of silicosis in Turkey. Following the discovery of several cases of silicosis in (young) workers who used this process, the frequency and main occupational risk factors of silicosis among former denim sandblasters in the region of Erzurum (Turkey) were evaluated. Demographic characteristics and information on working conditions were obtained by questionnaire and interview. In addition, spirometry testing was performed and chest radiographs were evaluated according to International Labour Office (ILO) classification of pneumoconioses in 157 former denim sandblasters. All subjects were male, with a mean (range) age of 23 (15-44) yrs. They had worked for a mean (range) of 36 (1-120) months, starting employment at a 17 (10-38) yrs of age. Most subjects (83%) had respiratory symptoms, especially dyspnoea (52%) but also chest pain (46%). Radiological evidence of silicosis (ILO score 1/0 or higher) was present in 77 (53%) out of 145 subjects with interpretable chest radiographs. These subjects had lower forced expiratory volume in one second and forced vital capacity. The risk of silicosis correlated with seniority (i.e. working as a foreman), exposure duration and number of places of work. Considering the high prevalence rate of silicosis in such workplaces, further problems are inevitable in the future unless effective measures are taken.

Radiographic readings for asbestosis: Misuse of science—validation of the ILO classification

Radiographic readings for pneumoconiosis (both asbestosis and silicosis), even those using the International Labour Office (ILO) Classification, have received widespread negative coverage in the media and strong judicial rebuke. The medical literature over the past 90 years was reviewed for the relationships between radiographic severity (standardized as the ILO profusion score) and indices of exposure to silica or asbestos, tissue burden of silica particles or asbestos fibers, histologic fibrosis, various measurements of pulmonary function and mortality. Evidence from many different disciplines has demonstrated that the ILO profusion score correlates with occupational exposure, dust burden in the lung, histologic fibrosis and, more recently, with physiologic impairment and mortality. The ILO Classification has therefore been validated as a scientific tool. Its fraudulent misuse by "hired-gun" physicians, attorneys and elements of the compensation system to falsify claims of asbestosis and/or silicosis (often in the same claimant) must be condemned.

Conglomerated masses of silicosis in sandblasters: High-resolution CT findings

The purpose of this study was to describe the high-resolution CT aspects of the silicosis and progressive massive fibrosis in sandblasters. The study was performed with 25 consecutive patients with silicosis and large opacities on chest radiography according to the International Labor Office (ILO) classification of pneumoconiosis. All patients presented with conglomerate masses involving the upper lobes, and in 92% of the cases the lesions were located in the posterior region of the lungs. The masses frequently showed nodular contour (76%), air bronchograms (76%), foci of calcification (72%), paracicatricial emphysema (72%), and adjacent pleural thickening (92%). Calcification of hilar or mediastinal lymph nodes (96%), mainly of the egg-shell type (56%), was also a common finding. In conclusion, in this specific group of patients, the sandblasters, the high-resolution CT demonstrated conglomerated masses with nodular contour, air bronchograms and foci of calcification, which were distributed mainly in the posterior region of the upper lobes. Calcification of hilar or mediastinal lymph nodes was also commonly seen.

Radiological Findings, Pulmonary Function and Dyspnea in Underground Coal Miners

Background: Respiratory disability induced by dust exposure in coal workers is assessed by pulmonary function tests and radiological evidence of pneumoconiosis. High-resolution computed tomography (HR-CT) improves the visibility of tissue changes, but the value of the findings for the clinical evaluation is controversial. Objectives: It was the aim of this study to evaluate the correlation between the International Labour Office (ILO) classification and the degree of emphysema in HR-CT with self-reported dyspnea and pulmonary function tests including diffusion capacity for CO (D_L,CO). Methods: We investigated 87 coal miners (aged 67 ± 6 years), having worked underground for 26 ± 9 years, with pulmonary function tests and HR-CT. Univariate associations were tested with correlation coefficients, and multivariable analyses used a stepwise forward regression model. Results: No aspect of the ILO classification showed a univariate correlation with dyspnea or forced expiratory flow in 1 s (FEV₁). Emphysema CT score was strongly associated with D_L,CO (r_s = –0.40; p < 0.001) and FEV₁/maximal vital capacity (r = –0.38; p < 0.001) in univariate analysis, but not with the clinical grade of dyspnea (r = –0.14; p = 0.256). CT emphysema score but not ILO classification was associated with FEV₁ in multivariable analyses (r_s = –0.37; p < 0.001). Dyspnea was best approximated by D_L,CO (r = –0.312; p = 0.008). Conclusion: The clinical grade of breathlessness was best approximated by D_L,CO. HR-CT showed a good association with expiratory flow limitation. ILO classification of the chest radiograph may be a marker of exposure but conveys little information about the degree of respiratory impairment.