Enclosure 6 - International Labour Office (ILO) Revision of the International Classification of Radiographs of Pneumoconioses

Our plain-English summary of Enclosure 6 - International Labour Office (ILO) Revision of the International Classification of Radiographs of Pneumoconioses, by International Labor Office (1969).

The study

• Author: International Labor Office
• Published: 1969
• Type of article: Report
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This is not a study of patients or workers. It is an International Labour Office (ILO) document reporting how experts meeting in Geneva in December 1968 revised the 1958 international system for classifying chest X-rays of pneumoconioses (lung diseases from inhaled mineral dusts). The ILO had first surveyed users of the 1958 system about difficulties. The experts produced two compatible schemes: a Short Classification mainly for clinical use, and an Extended Classification for epidemiological studies of pneumoconioses from all mineral dusts, including asbestos and beryllium. The Extended scheme graded small 'irregular' opacities, pleural thickening, pleural calcification and an ill-defined ('shaggy') heart outline, which the document describes as a recognised feature of asbestosis. It also added an optional 12-point profusion scale for small rounded and irregular opacities. The document states that the classification does not set legal definitions or compensation levels. It recommends more standard films, particularly for asbestosis. It notes that links between irregular opacities and dust exposure, lung function and mortality are much less well established than for rounded opacities. It gives advice on chest X-ray technique.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Report of an ILO expert meeting revising a classification scheme for chest radiographs, with notes on its use and on radiographic technique; not a study of patients or workers
• Who was studied: No patients or workers were studied. The revision followed an ILO inquiry among users of the 1958 classification and a meeting of consultants from several countries, convened in Geneva in December 1968
• Exposure: Mineral dusts generally, including coal, carbon, asbestos and beryllium. For pleural calcification, the document names asbestos, tremolite, talc and some other minerals as one of three main causes
• Main results:
  • Two mutually compatible schemes were adopted: a Short Classification mainly for clinical purposes, and an Extended Classification for epidemiological and other studies of the pneumoconioses
  • In the Short Classification, small rounded opacities are graded only by profusion, in three categories. Category 2, for example, is defined as small rounded opacities that are numerous in both lungs
  • Obligatory symbols in the Short Classification include significant pleural abnormalities, calcified pleural plaques, and suspect neoplasm
  • The Extended Classification grades pleural thickening (calcified and uncalcified) separately from lung changes. The document describes these as features induced by exposure to asbestos and some other minerals
  • The 'shaggy' heart was classified separately, as an ill-defined cardiac outline, because it has long been recognised as a feature of asbestosis
  • A 12-point scale of profusion for small rounded and irregular opacities was introduced as an optional extra in the Extended Classification
  • The experts recommended that the ILO select additional standard films, particularly for asbestosis
  • For chest radiography, a high kilovoltage technique was recommended
• The authors' conclusion: The experts considered that the Short and Extended Classifications together are likely to meet the needs of both clinicians and epidemiologists. They state that the classification does not imply legal definitions of pneumoconiosis for compensation purposes
• Limitations the authors state:
  • The relationship of irregular (linear) opacities to dust exposure, lung function and mortality is much less well established than for rounded opacities
  • Classifying such diverse features inevitably involves some over-simplification of patterns that different observers may see differently
  • Miniature films may reduce accuracy, particularly for early pneumoconiosis
  • It was uncertain whether films showing only pleural thickening believed to be caused by asbestos should be classified as asbestosis
  • Further research is needed to confirm the usefulness of separately classifying the cardiac and diaphragm outlines

Topics

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Pleural Thickening, Pleural Calcification.

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