The occurrence of pleural calcification among asbestos insulation workers

Our plain-English summary of The occurrence of pleural calcification among asbestos insulation workers, by I.J. Selikoff (Annals of the New York Academy of Sciences, 1965).

The study

• Author: I.J. Selikoff
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):351-67
• Cited by: 96 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. 002508).

Abstract

1. Roentgenographic study of 1,117 asbestos insulation workers showed pleural calcification to be a common finding. Altogether, 150 instances of such calcification were present.
2. Data is presented which demonstrates that pleural calcification among workmen exposed to asbestos in this trade rarely occurs in less than 20 years from onset of exposure. Pleural calcification was found in 5 of 725 asbestos insulation workers with less than 20 years from onset of exposure but in 145 of 392 men examined more than 20 years from beginning work with asbestos. Similarly, the extent of calcification also increased with duration of exposure.
3. Available data suggests that both total amount of exposure as well as lapsed time from onset of exposure are of importance. In this group of men, the earliest case seen was in a man examined 12 years from onset of exposure. Elsewhere, somewhat shorter periods from onset of exposure have been noted, but such cases are rare.
4. Approximately half the cases were bilateral. In unilateral cases, involvement of the left hemithorax predominated. Extensive calcification was usually bilateral.
5. Bilateral pleural calcification is almost pathognomonic of pleural disease associated with pneumoconiosis. Asbestos is by far the most common industrial dust involved and bilateral pleural calcification in the absence of evidence of traumatic or infectious pleural disease can usually be considered to be due to asbestos exposure.
6. In half the cases, the calcification found was unilateral. The appearance and location of such calcification is described and no portion of the pleura was found to be immune. The diagnostic importance of such unilateral calcification is stressed since even unilateral calcification is uncommon in the general population and when it occurs, a traumatic or infectious history can generally be obtained. When the calcification is idiopathic, it should strongly suggest asbestosis and the presence of unilateral pleural calcification is almost as strongly diagnostic of asbestosis as is bilateral calcification.
7. The pleural calcification is primarily found in the parietal pleura, more heavily in the lower portions of the chest. Data concerning correlations with pleural fibrosis and asbestotic parenchymal fibrosis is given. Pleural calcification not infrequently is present in the absence of visible pleural fibrosis and occasionally may be present in the absence of radiologically visible parenchymal fibrosis.
8. In addition to standard posteroanterior films, it has been found advantageous to use two additional simple techniques; a second posteroanterior film taken with a slightly more penetrating technique and the use of oblique projections.
9. At the present time, it is likely that asbestos exposure is the most common cause of pleural calcification. The finding of such calcification as described here generally indicates asbestos exposure more than 20 years before.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This article began with a review of earlier reports and then presented an X-ray survey of asbestos insulation workers. The author studied 1,258 union insulation workers in the New York-New Jersey area and examined 1,117 of them in 1963-1964, using standard, more penetrating and oblique chest films. Pleural calcification was found in 150 of the 1,117 men. It was found in 5 of 725 men with less than 20 years since first exposure, and in 145 of 392 men examined more than 20 years after first exposure. Among these men, the earliest case was seen 12 years after first exposure; the author noted shorter periods elsewhere, but called such cases rare. The extent of calcification increased with longer duration of exposure. Calcification was bilateral in 73 of the 150 cases. It sometimes appeared without visible pleural or lung fibrosis. The author noted that the effects of total years of exposure and time since first exposure were hard to separate. The author concluded that such calcification generally indicates asbestos exposure more than 20 years before.

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 of union asbestos insulation workers, preceded by a historical review of earlier reports
• Who was studied: 1,258 current members of the International Association of Heat and Frost Insulators and Asbestos Workers in the New York-New Jersey Metropolitan area (all living members on the rolls on December 31, 1942 or joining 1943-1962). 1,117 were examined (89.9%) in a 1963-1964 survey.
• Exposure: Asbestos exposure in insulation work. Fiber types were not specified. Exposure was analyzed by years since onset of exposure and by total years of work exposure.
• Main results:
  • Pleural calcification was found in 150 of the 1,117 men examined.
  • Calcification was found in 5 of 725 men with less than 20 years from onset of exposure, and in 145 of 392 men examined more than 20 years after beginning work with asbestos.
  • By time since onset of exposure, calcification was found in:
• 0 of 346 men (less than 10 years)
• 5 of 379 men (10 to 19 years)
• 8 of 77 men (20 to 29 years)
• 67 of 194 men (30 to 39 years)
• 70 of 121 men (40 years or more)
  • Among the 70 men with calcification in the group 40 or more years from onset of exposure, almost half had extensive calcification (Grade II or III).
  • The author examined 331 men whose exposure began at least 25 years before the survey, in two groups:
• 54 men with less than 25 years of total exposure: 11 had calcification, all minimal.
• 277 men whose total exposure approximated the time since onset: 127 had calcification.
  • In this survey group, the earliest case was a man examined 12 years from onset of exposure.
  • Outside this survey, the author reported that somewhat shorter periods from onset of exposure had been noted, but that such cases are rare. One example was a small area of calcification in an oil burner repair worker examined seven years after beginning work in that trade.
  • Of the 150 cases:
• 73 were bilateral.
• 49 involved the left side only.
• 28 involved the right side only.
  48 of the 54 extensive cases were bilateral, compared with 25 of the 96 limited cases.
  • Among 392 men with at least 20 years from onset of exposure, 240 had no X-ray evidence of pleural fibrosis. Of these 240, 69 (28.8 per cent) showed some calcification.
  • Among the same 392 men, 53 of 100 with extensive parenchymal (lung) fibrosis had no calcification. 4 of 56 with no parenchymal fibrosis had minimal calcification.
• The authors' conclusion: The author concluded that among these insulation workers pleural calcification was very uncommon in less than 20 years from onset of exposure. The author also concluded that asbestos exposure is likely the most common cause of pleural calcification, and that such calcification generally indicates asbestos exposure more than 20 years before. Both bilateral and unilateral calcification without a history of trauma or infection were described as strongly suggesting asbestosis.
• Limitations the authors state:
  • The effect of actual years of work exposure was difficult to separate from time since first exposure, because the two often coincided in these men.
  • Additional X-ray techniques (tomography, lateral views, Bucky diaphragm) were not used routinely and might slightly increase the yield. The author had no data on their routine use.
  • Experience with repeated (serial) X-ray observations was limited.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Calcification, Insulator, Bilateral, Hemithorax, Pneumoconiosis, Asbestos Exposure, Pleura, Idiopathic.

Related studies

• Atherosclerotic and pleural calcifications are related among asbestos-exposed workers — T. Vehmas, A. Hiltunen, et al. (2008)
• Metsovo lung: pleural calcification and restrictive lung function in northwestern Greece. Environmental exposure to mineral fiber as etiology — S.H. Constantopoulos, J.A. Goudevenos, et al. (1985)
• Pleural calcification, pleural mesotheliomas, and bronchial cancers caused by tremolite dust — S. Yazicioglu, R. Ilçayto, et al. (1980)
• Pleural calcification associated with exposure to chrysotile asbestos in southeast Turkey — S. Yazicioglu (1976)
• Metsovo lung outside Metsovo. Endemic pleural calcifications in the ophiolite belts of Greece — S.H. Constantopoulos, P. Theodoracopoulos, et al. (1991)
• Tremolite whitewashing and pleural calcifications — S.H. Constantopoulos, N.A. Saratzis, et al. (1987)

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