Roentgenographic Lung Changes, Asbestosis And Mortality In A Belgian Asbestos-Cement Factory

Our plain-English summary of Roentgenographic Lung Changes, Asbestosis And Mortality In A Belgian Asbestos-Cement Factory, by L.M. Lacquet, L. Van Der Linden, J. Lepoutre (1980).

The study

• Authors: L.M. Lacquet, L. Van Der Linden, J. Lepoutre
• Published: Biological Effects Of Mineral Fibres (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 30, Pp. 783-793 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 000825. The article is still under copyright, so we describe it here rather than post it.

In plain English

This study looked at workers at the Eternit asbestos-cement factory at Kapelle op de Bos, Belgium. The factory used chrysotile, crocidolite and amosite to make building materials and pipes. In 1975, 1973 of 2650 enlisted employees had a work history taken and a chest X-ray. Each worker's exposure was estimated in 'fibre-years'. The authors called past dust estimates good guesses at best. Small lung opacities, pleural adhesions and pleural thickening on X-ray increased significantly with fibre-years. The trend for calcified pleural plaques was not significant. Among male workers followed from 1963 to 1977, 29 cases of asbestosis were found, rising strongly with exposure, with none below 100 fibre-years. Overall deaths did not differ significantly from Belgian national rates, but deaths from external causes were significantly in excess. Respiratory cancer deaths were not in excess: 22 were observed against 22.35 expected. These included one pleural mesothelioma, which the authors considered almost certainly related to heavy exposure. Gastrointestinal cancer deaths were in excess, with 17 observed against 11.80 expected, but the authors found no significant relationship with fibre-years. The authors concluded there was a strong dose-response relationship for asbestosis.

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: Cross-sectional chest X-ray survey (1975) combined with a study of asbestosis incidence and mortality in male workers from 1963 to 1977. Deaths were compared with Belgian national rates and, for respiratory and gastrointestinal cancer, with matched internal controls (4 per case).
• Who was studied: Employees of the Eternit asbestos-cement factory at Kapelle op de Bos, Belgium. In 1975, 2650 employees were enlisted, of whom 1973 (74.5%) had a history and chest X-ray; 15 were then excluded for sarcoidosis or silica exposure. The asbestosis and mortality study covered male workers who worked at least 12 months in the factory between 1963 and 1977 (29,366 man-years).
• Exposure: The factory processed about 35,000 tons of chrysotile, 3000 tons of crocidolite and 1000 tons of amosite a year to make asbestos-cement building materials and pipes. Individual exposure was expressed in fibre-years, based on work area and year. Fibre counts were available only for 1970 to 1976; earlier, higher levels were estimated.
• Main results:
  • Among employees X-rayed in 1975, the trend with fibre-years (examined by age group) was significant for small lung opacities grades 1 and 2.
  • The trend with fibre-years was significant for pleural adhesions (P = 0.002) and pleural thickening (P = 0.01).
  • The trend with fibre-years was not significant for calcified plaques.
  • After removing 175 cases with evidence of chest trauma, tuberculosis or empyema, the trends remained: pleural adhesion P = 0.008, pleural plaques P = 0.005.
  • 29 cases of asbestosis were found among male workers during the 1963 to 1977 observation period. The number increased highly significantly with fibre-years.
  • No asbestosis was seen at exposures below 100 fibre-years, and only one case in the 100 to 200 fibre-year range.
  • Two workers who had never handled free asbestos fibres developed asbestosis. Their exposures were high: 435 and 350 fibre-years, from work where asbestos-cement products were finished.
  • Total mortality among male workers was not significantly different from that expected for a Belgian population of the same age and sex.
  • There was a significant excess of deaths from external causes.
  • Deaths from non-malignant respiratory disease were in excess, but not significantly. The authors attributed this probably to seven deaths from asbestosis.
  • Male workers had 22 respiratory cancer deaths against 22.35 expected, and 17 gastrointestinal cancer deaths against 11.80 expected. The authors reported the gastrointestinal excess as significant.
  • Respiratory cancers included three cancers of the upper airways, 17 lung cancers and one pleural mesothelioma. The authors considered the mesothelioma almost certainly related to heavy exposure.
  • No significant relationship was found between the gastrointestinal cancer excess and fibre-years.
  • Compared with matched internal controls, cancer cases showed no significant difference in fibre-year exposure.
• The authors' conclusion: The authors concluded that, for these workers:
• there was a strong dose-response relationship for asbestosis, with no case below 100 fibre-years;
• there was a dose-response relationship for small lung opacities, pleural adhesions and pleural thickening;
• general mortality was not in excess, but accidental deaths were;
• deaths from malignant tumours and from respiratory cancer were not in excess;
• gastrointestinal cancer deaths were in excess, but this showed no dose-response relationship.
• Limitations the authors state:
  • The authors described their estimates of past dust concentrations as only good guesses at best. They added that these were unlikely to be wrong by more than one order of magnitude.
  • The authors noted that comparing a workforce with national statistics may be questionable because of the 'healthy worker effect'. They used internal controls to address this.
  • The authors could not tell from their data whether asbestos-cement dust is less fibrogenic in itself than free asbestos, because less dust is generated by handling asbestos-cement.
  • Grades of pleural changes were pooled because few were observed.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Eternit, Chrysotile, Crocidolite, Amosite, Occupational History, Chest X-Ray, Pleural Thickening.

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