Migration and work in postwar Australia: mortality profile comparisons between Australian and Italian workers exposed to blue asbestos at Wittenoom

Our plain-English summary of Migration and work in postwar Australia: mortality profile comparisons between Australian and Italian workers exposed to blue asbestos at Wittenoom, by A. Reid, E. Merler, S. Peters, et al (Occupational and Environmental Medicine, 2018).

The study

• Authors: A. Reid, E. Merler, S. Peters, N. Jayasinghe, V. Bressan, P. Franklin, F. Brims, N.H. de Klerk, A.W. Musk
• Journal: Occupational and Environmental Medicine
• Published: 2018;75(1):29-36
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Three hundred and thirty thousand Italians arrived in Australia between 1945 and 1966, many on assisted passage schemes where the worker agreed to a 2-year unskilled employment contract. Italians were the largest of 52 migrant groups employed at the Wittenoom blue asbestos mining and milling operation. We compare mortality from asbestos-related diseases among Italian and Australian workers employed at Wittenoom.

Methods: A cohort of 6500 male workers was established from employment records and followed up at state and national mortality and cancer registries. SMRs were calculated to compare mortality with the Western Australian male population. Time-varying Cox proportional hazards models compared the risk of mesothelioma between Australian and Italian workers.

Results: 1031 Italians and 3465 Australians worked at Wittenoom between 1943 and 1966. Duration of employment was longer for the Italian workers, although the concentration of exposure was similar. The mesothelioma mortality rate per 100 000 was higher in Italians (184, 95% CI 148 to 229) than Australians (128, 95% CI 111 to 149). The risk of mesothelioma was greater than twofold (HR 2.27, 95% CI 1.43 to 3.60) in Italians at the lowest asbestos exposure category (<10 fibre years/per mL).

Conclusions: A hierarchy in migration, isolation and a shortage of workers led to Italians at Wittenoom incurring higher cumulative exposure to blue asbestos and subsequently a greater rate of malignant mesothelioma than Australian workers.

Impact: Poor working conditions and disparities between native and foreign-born workers has had a detrimental and differential impact on the long-term health of the workforce.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

In plain English

This cohort study compared deaths among men who worked at the Wittenoom crocidolite (blue asbestos) mine and mill in Western Australia between 1943 and 1966. It covered 1031 Italian and 3465 Australian workers, followed to the end of 2009, including 297 Italians who returned to Italy. Average exposure intensity was similar in the two groups, but Italians worked longer and so had greater cumulative exposure. Compared with Western Australian men, both groups had more deaths than expected from lung cancer and pneumoconiosis. There were 176 mesotheliomas among Australians and 79 among Italians. The mesothelioma death rate per 100 000 person-years was 184 (95% CI 148 to 229) in Italians and 128 (111 to 149) in Australians. In the lowest exposure category (under 10 fibre years per mL), Italians had a hazard ratio for pleural mesothelioma of 2.27 (1.43 to 3.60) compared with Australians. The authors concluded that Italians incurred higher cumulative exposure and a greater rate of pleural and peritoneal mesothelioma. They noted that unrecorded overtime may have misclassified Italians' exposure, that numbers were small, and that later jobs were unknown.

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: Retrospective cohort study using standardised mortality ratios (SMRs) against Western Australian and Italian male death rates, and time-varying Cox proportional hazards models comparing Italian and Australian workers
• Who was studied: Male workers of the Australian Blue Asbestos Company at Wittenoom, Western Australia, employed 1943 to 1966: 1031 Italians (identified by recorded nationality and Italian-sounding names, reviewed by Italian collaborators) and 3465 Australians (those identifying as 'Australian' or 'Australian or British'). Follow-up ran to 31 December 2009. 297 Italians (29%) returned to Italy and were traced there.
• Exposure: Crocidolite (blue asbestos) from mining and milling at Wittenoom. Individual cumulative exposure was estimated in fibre years per mL from job histories and dust measurements, then grouped as low (under 10), medium (10 to 50) and high (over 50) f/mL years.
• Main results:
  • Italians worked longer than Australians (median duration 202 days, IQR 66–526, versus 100 days, IQR 38–267). Exposure intensity was similar (18.1 versus 18.5 f/mL years). Cumulative exposure was greater in Italians: 9.25 f/mL years (IQR 2.79–33.8) versus 4.85 (IQR 1.35–15.8) in Australians.
  • Compared with Western Australian men, lung cancer and pneumoconiosis deaths were in excess in both groups. Using SMR1, lung cancer was 1.58 (95% CI 1.37 to 1.80) in Australians and 1.80 (1.40 to 2.27) in Italians. Pneumoconiosis was 15.9 (12.2 to 20.3) in Australians and 28.6 (19 to 41.3) in Italians.
  • Cancers of the larynx and pharynx were in excess among Italians (SMR1 2.54, 95% CI 1.10 to 5.00) but not among Australians (SMR1 0.89, 0.41 to 1.69).
  • There were 176 mesotheliomas among Australians and 79 among Italians to the end of 2009. The all-mesothelioma death rate per 100 000 person-years was 184 (95% CI 148 to 229) in Italians and 128 (95% CI 111 to 149) in Australians.
  • The peritoneal mesothelioma rate per 100 000 was 40 (95% CI 25 to 64) in Italians and 17 (11 to 25) in Australians, which the authors described as two and a half times greater in Italians.
  • In the lowest cumulative exposure category (under 10 f/mL years), Italians had a hazard ratio for pleural mesothelioma of 2.27 (95% CI 1.43 to 3.60) compared with Australians.
  • The authors reported that the risk was not statistically different between the groups in the medium and high exposure categories. Table 5 gives hazard ratios for Italians versus Australians of 0.47 (95% CI 0.26 to 0.86) for medium exposure and 0.60 (0.32 to 1.13) for high exposure.
  • Among Australians, pleural mesothelioma risk rose with cumulative exposure: hazard ratio 3.92 (2.69 to 5.72) for medium and 6.31 (3.93 to 10.1) for high exposure, compared with low. Among Italians the pattern was not as clear: 0.81 (0.42 to 1.56) for medium and 1.67 (0.90 to 3.1) for high.
• The authors' conclusion: The authors concluded that isolation, a transient migrant workforce with fixed employment periods and blue asbestos exposure meant that Italian workers at Wittenoom incurred higher cumulative exposure than Australian workers and subsequently a greater rate of pleural and peritoneal mesothelioma.
• Limitations the authors state:
  • The number of subjects was relatively small, especially when Italians were split into those who stayed in Australia and those who returned to Italy.
  • Jobs held after leaving Wittenoom, including any further asbestos exposure, were generally not known.
  • Exposure may have been misclassified more often for Italians, because overtime hours they often worked were not included in the exposure calculations. This may explain the missing exposure–response pattern among Italians.
  • Many mesotheliomas were identified from death certificates, so some cases may have been missed, particularly among those who returned to Italy.
  • A 'healthy migrant effect' may have biased comparisons with the general population towards the null, although the authors considered this unlikely to affect mesothelioma, lung cancer or pneumoconiosis.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Crocidolite, Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Crocidolite, Wittenoom, Mesothelioma, Asbestos Exposure, Cumulative Exposure, Malignant Mesothelioma.

Related studies

• Are children more vulnerable to mesothelioma than adults? A comparison of mesothelioma risk among children and adults exposed non-occupationally to blue asbestos at Wittenoom — A. Reid, P. Franklin, et al. (2018)
• Predicted mortality from malignant mesothelioma among women exposed to blue asbestos at Wittenoom, Western Australia — A. Reid, G. Berry, et al. (2009)
• Mortality of former crocidolite (blue asbestos) miners and millers at Wittenoom — A.W. Musk, N.H. de Klerk, et al. (2008)
• Retinol supplementation and mesothelioma incidence in workers earlier exposed to blue asbestos (Crocidolite) at Wittenoom, Western Australia — H.S. Alfonso, A. Reid, et al. (2010)
• Cancer incidence among women and girls environmentally and occupationally exposed to blue asbestos at Wittenoom, Western Australia — A. Reid, J. Heyworth, et al. (2008)
• Variations in mesothelioma mortality rates among migrants to Australia and Australian-born — S. Si, S. Peters, et al. (2018)

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