Mortality and Cancer Incidence After Exposure to Blue Asbestos in Childhood: A Further 10 Years of Follow-Up

Our plain-English summary of Mortality and Cancer Incidence After Exposure to Blue Asbestos in Childhood: A Further 10 Years of Follow-Up, by R.N. Carey, A. Reid, N. de Klerk, et al (American Journal of Industrial Medicine, 2025).

The study

• Authors: R.N. Carey, A. Reid, N. de Klerk, P. Cinquini, N. Olsen, F. Brims, P. Franklin
• Journal: American Journal of Industrial Medicine
• Published: 2025;68(9):772-783
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: The impact of early-life exposure to asbestos on disease risk remains uncertain. Childhood exposure to blue asbestos at Wittenoom has previously been linked to the development of malignant mesothelioma and various cancers in adulthood, as well as to a greater risk of all-cause mortality compared with the general population. This study aims to provide an update on mortality and cancer incidence rates after this exposure.

Methods: The cohort of all those who lived in the asbestos mining town of Wittenoom as children (less than 15 years of age; 1279 males and 1185 females) was linked to state and national cancer and death registries. We calculated standardized incidence ratios (SIRs) for a range of cancers, and standardized mortality ratios (SMRs) for all-cause and cause-specific mortality for the cohort compared with the general Western Australian population.

Results: Compared with the Western Australian population, males from the cohort had an increased risk of all cancers and mesothelioma, as well as melanoma and cancers of the lip and mouth, liver, and brain. Females had a significantly elevated risk of all cancers, mesothelioma, and cancers of the ovary and brain. Higher rates of mesothelioma were observed among those with a longer duration of exposure and higher cumulative exposure, consistent with a known exposure-response relationship. Former Wittenoom children also had a greater risk of all-cause mortality and mortality from cancer, mesothelioma, and ill-defined symptoms.

Conclusions: This update confirms earlier studies and shows that exposure to asbestos in childhood is associated with several cancer and mortality outcomes in adulthood.

© 2025 The Author(s). American Journal of Industrial Medicine published by Wiley Periodicals LLC.

In plain English

This study updated earlier research on 2,464 people (1,279 males, 1,185 females) who lived as children under 15 in Wittenoom, Western Australia, a town near a crocidolite (blue asbestos) mine, and who did not later work in the Wittenoom mine or mill. Linking them to cancer and death registries (to the end of 2018 and 2019 respectively), the authors compared them with the general Western Australian population. Because approximately 20% were lost to follow-up, results were calculated two ways, giving low and high estimates. Mesothelioma cases were 33.81 (95% CI 24.93–44.83) to 58.97 (43.48–78.18) times the expected number in males and 62.51 (40.05–93.01) to 104.61 (67.02–155.65) times in females. Lung cancer was not significantly increased. Females had more ovarian cancer than expected, and males more lip and mouth and liver cancer. Deaths from any cause were 1.48 (1.30–1.67) to 2.11 (1.86–2.39) times expected in males and 1.29 (1.08–1.54) to 1.86 (1.55–2.21) times in females. Mesothelioma rates were higher with longer and higher cumulative exposure. The authors concluded that childhood asbestos exposure is associated with several cancer and mortality outcomes in adulthood.

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: Cohort study (updated follow-up of an existing cohort) using registry linkage. Standardized incidence ratios and standardized mortality ratios were calculated against the Western Australian population, using two censoring methods that give a minimum and a maximum estimate.
• Who was studied: 2,464 people (1,279 males, 1,185 females) from the Wittenoom residents' cohort who lived in Wittenoom, Western Australia, as children under 15 years of age. Children who reported later working in the Wittenoom mine or mill (81) were excluded. Cancer incidence was followed from 1982 to the end of 2018 and deaths from 1950 to the end of 2019.
• Exposure: Non-occupational childhood exposure to crocidolite (blue asbestos) from the mine and mill and from mine tailings used around the town. Exposure was estimated from dust surveys and the years of residence. Cumulative exposure ranged from 0.01 to 68.7 f/mL-years, with a median of 3.4 f/mL-years.
• Main results:
  • Males (48 mesothelioma cases in the SIR analysis): mesothelioma SIR 33.81 (95% CI 24.93–44.83) with censoring method 1 and 58.97 (95% CI 43.48–78.18) with method 2.
  • Females (24 mesothelioma cases): mesothelioma SIR 62.51 (95% CI 40.05–93.01) with method 1 and 104.61 (95% CI 67.02–155.65) with method 2.
  • Females: increased risks of mesothelioma and ovarian cancer were found with both censoring methods. Ovarian cancer (9 cases) had an SIR of 2.38 (1.09–4.52) with method 1 and 3.51 (1.61–6.67) with method 2.
  • Males: higher risks of lip and mouth cancer and liver cancer were found with both censoring methods. Higher risks of brain cancer and melanoma were found with method 2 only. Prostate cancer risk was significantly decreased with method 1 only.
  • Females: brain cancer risk was significantly elevated with method 2 only. Colorectal cancer risk was significantly decreased with method 1 only.
  • The risk of death from lung cancer was not significantly increased in either males or females.
  • Males: the all-cause mortality SMR was 1.48 (95% CI 1.30–1.67) with method 1 and 2.11 (95% CI 1.86–2.39) with method 2. The article describes this as a 48% to 111% greater risk than the Western Australian male population.
  • Females: the all-cause mortality SMR was 1.29 (95% CI 1.08–1.54) with method 1 and 1.86 (95% CI 1.55–2.21) with method 2. The article describes this as a 29% to 86% greater risk than the Western Australian female population.
  • Mesothelioma rates were higher among those with longer duration of exposure and higher cumulative exposure, and rose with time since first exposure.
  • Age at first exposure showed no linear trend: those first exposed at ages 5 to 9 years had higher mesothelioma rates than the other age groups.
  • Death from ill-defined signs and symptoms was increased in both sexes. Most of these deaths (15 of 18) occurred in 1950–1976, and the authors said the finding was possibly an artifact of coding.
• The authors' conclusion: The authors concluded that this update confirms earlier studies and shows that exposure to asbestos in childhood is associated with several cancer and mortality outcomes in adulthood. They also stated that the risk of mesothelioma from childhood exposure remained lower than the risk from nonoccupational exposure in adult life.
• Limitations the authors state:
  • Exposure estimates were based on the period and duration of residence, not on personal measurements, and did not account for differences such as activity patterns.
  • There was no information on asbestos exposure after leaving Wittenoom.
  • It is unclear how representative the cohort is of the general Western Australian population. Members were more likely to live in regional or rural areas, which may have influenced the findings.
  • Some participants were lost to follow-up and may differ from those retained, so the authors said the estimates should be interpreted with some caution.
  • Some outcomes still have too few cases to determine risk; for example, there were only three laryngeal cancer cases.
  • The brain cancer finding was based on fewer than 10 cases and was significant only with the censoring method that may overestimate the rate.
  • The authors considered the melanoma findings likely to reflect lifestyle factors such as alcohol and sun exposure rather than asbestos.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Crocidolite.

Medical terms in this study, explained in our Lexicon: Crocidolite, Wittenoom, Mesothelioma, Incidence, Standardized Incidence Ratio (SIR), standardized mortality ratio (SMR), Cumulative Exposure.

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)
• Cancer incidence among women and girls environmentally and occupationally exposed to blue asbestos at Wittenoom, Western Australia — A. Reid, J. Heyworth, et al. (2008)
• Aerodigestive and gastrointestinal tract cancers and exposure to crocidolite (blue asbestos): incidence and mortality among former crocidolite workers — A. Reid, G. Ambrosini, et al. (2004)
• 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)
• Age and sex differences in malignant mesothelioma after residential exposure to blue asbestos (crocidolite) — A. Reid, G. Berry, et al. (2007)
• Migration and work in postwar Australia: mortality profile comparisons between Australian and Italian workers exposed to blue asbestos at Wittenoom — A. Reid, E. Merler, et al. (2018)

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