Mesothelioma incidence in a Dutch shipyard

Our plain-English summary of Mesothelioma incidence in a Dutch shipyard, by J. Stumphius (Annals of the New York Academy of Sciences, 1979).

The study

• Author: J. Stumphius
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:317-22
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004021).

Abstract

On Walcheren Island (the Netherlands), 25 cases of mesothelioma were diagnosed from 1962 to 1968. In 22 cases, there had been an occupational association with Royal Schelde, the shipyard in Vlissingen. A relationship with exposure to asbestos, frequently used in shipbuilding in the past, could be demonstrated. Further observations showed the expected increase of mesothelioma cases in Royal Schelde workers. In 1974, the number of cases totaled 42; in 1978, the number rose to 57. In addition, five more recent cases have not yet been confirmed histologically, but the clinical symptoms are unmistakable. In seven of 12 mesothelioma cases on Walcheren Island that had no association with Royal Schelde, asbestos exposure in the occupational history could also be traced. Finally, a few facts are mentioned about the recent Dutch Asbestos Act.

In plain English

This article reported a continuing survey of mesothelioma on Walcheren Island, the Netherlands, home of the Royal Schelde shipyard (about 3100 employees). Of 25 cases diagnosed there from 1962 to 1968, 22 had an occupational association with the shipyard. The author grouped shipyard workers by past asbestos exposure, judged from their work, as certain, probable, or possible or none. For the 1974 to 1978 update, only histologically confirmed cases were tabulated; five unconfirmed shipyard patients were left out. By 1978 there were 33 cases among 500 workers with certain exposure (6.60 per 100), 14 among 753 probable (1.86 per 100), and 9 among 1849 possible or none (0.49 per 100). The difference between the certain group and the other two was reported as statistically significant. Many asbestos fibers were found in patients' lungs, but asbestosis could not be diagnosed. In a few cases, electron microscopy showed chrysotile and amphibole fibers. Seven of 12 island cases with no shipyard link had occupational asbestos exposure. The author concluded that asbestos is an obvious cause of mesothelioma and expected more cases.

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: Descriptive follow-up survey (case series) of mesothelioma cases on one island, with attack rates calculated by past asbestos exposure category among the shipyard workforce
• Who was studied: Mesothelioma cases diagnosed on Walcheren Island, the Netherlands (about 100,000 inhabitants), from 1962 to May 1, 1978. The main group was people with an occupational association with the Royal Schelde shipyard, which had about 3100 employees (3102 in the tables).
• Exposure: Past asbestos exposure at the shipyard, classified from the nature of each worker's work as certain, probable, or possible or none. Insulation, including asbestos spraying, was done by a subcontractor's insulators. Exposure was definite for workers near the insulators and for those who worked with asbestos-containing materials, such as ship's carpenters. The yard stopped using asbestos for insulation in 1970.
• Main results:
  • 1962 to 1968: Of 25 mesothelioma cases on Walcheren Island, 22 had an occupational association with Royal Schelde. For one of these cases, the nature of past work could not be traced.
  • 1962 to 1968 attack rates among Royal Schelde workers: certain exposure, 9 cases among 500 (1.80 per 100); probable exposure, 6 cases among 753 (0.80 per 100); possible or no exposure, 6 cases among 1849 (0.32 per 100). The probable group size is printed as 153 in this table, but the article's percentage and later tables give 753.
  • 1962 to 1974 attack rates: certain exposure, 23 cases among 500 (4.60 per 100); probable exposure, 11 cases among 753 (1.46 per 100); possible or no exposure, 7 cases among 1849 (0.38 per 100).
  • 1962 to 1978 attack rates: certain exposure, 33 cases among 500 (6.60 per 100); probable exposure, 14 cases among 753 (1.86 per 100); possible or no exposure, 9 cases among 1849 (0.49 per 100). For the 1974 to 1978 period, only the 15 histologically confirmed shipyard-associated cases were added to these counts.
  • For both the 1962 to 1974 and 1962 to 1978 data, the difference between the certain exposure group and the other two groups was reported as statistically significant (p less than 0.001; chi-square 53.92 and 82.99, respectively).
  • From 1974 to May 1, 1978, 25 new mesothelioma cases were diagnosed on the island, 20 of them with a Royal Schelde association. Of these 20, 15 were histologically confirmed. The other five were not yet confirmed, although the author described their clinical symptoms as unmistakable.
  • Large numbers of asbestos fibers were always found in the patients' lung tissue, with no sign of fibrosis. Asbestosis could not be diagnosed in Royal Schelde workers.
  • In a few cases, electron microscopy identified the lung fibers as chrysotile and amphibole types.
  • Iron oxides were always present in the patients' lungs. Iron was considered as a possible cocarcinogen but appeared to be harmless.
  • Of 12 mesothelioma cases on Walcheren Island from 1962 to 1978 with no Royal Schelde association, 7 had asbestos exposure in their work histories: engine room mechanic (3), asbestos insulator (2), foundry worker (1) and pipe worker (1). For the other 5, past asbestos exposure could not be confirmed.
• The authors' conclusion: The author concluded that the follow-up survey again demonstrated that asbestos is an obvious cause of mesothelioma. Although asbestos exposure at the yard ceased in 1970, the author expected a considerable number of further cases because of the 20 to 40 year latency.
• Limitations the authors state:
  • Five of the 1974 to 1978 shipyard-associated cases had not been histologically confirmed and were left out of the 1978 exposure-group tabulation. The author said biopsies were avoided because of the risk of metastases in the scars.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma, Shipyards and maritime work.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Asbestos Exposure, Occupational History.

Related studies

• Incidence of bronchial carcinoma in shipyard workers with pleural plaques — J.R. Edge (1979)
• Incidence of lung cancer among shipyard welders investigated for siderosis — T.E. Danielsen, S. Lang rd, et al. (1998)
• Asbestos disease in United States shipyards — I.J. Selikoff, R. Lilis, et al. (1979)
• Mortality among shipyard workers in Genoa, Italy — R. Puntoni, M. Vercelli, et al. (1979)
• Case-control study of lung cancer in civilian employees at the Portsmouth Naval Shipyard, Kittery, Maine — R.A. Rinsky, J.M. Melius, et al. (1988)
• Prevalence of radiographic abnormalities among Northern California shipyard workers — P.L. Polakoff, B.R. Horn, et al. (1979)

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