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

Our plain-English summary of 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, by A. Reid, P. Franklin, G. Berry, et al (Occupational and Environmental Medicine, 2018).

The study

• Authors: A. Reid, P. Franklin, G. Berry, S. Peters, N. Sodhi-Berry, F. Brims, A.W. Musk, N.H. de Klerk
• Journal: Occupational and Environmental Medicine
• Published: 2018;75(12):898-903
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: The presence of asbestos in public buildings is a legacy of past asbestos use in many developed countries. Of particular concern is the amount and current condition in schools and the vulnerability of children to mesothelioma. Our aim was to compare the risk of mesothelioma between those exposed to blue asbestos as children and as adults at Wittenoom.

Methods: Public sources were used to establish the Wittenoom residents' cohort. Mesothelioma incidence rates per 100 000 person-years at risk were derived for those first exposed to asbestos at Wittenoom as children (<15 years) or adults separately. Proportional hazards survival models examined the slope of the exposure-response relationship between asbestos exposure and incidence of mesothelioma in different sex and age groups.

Results: The mesothelioma rate was lower among those first exposed as children (76.8 per 100 000) than those first exposed as adults (121.3 per 100 000). Adjusting for cumulative exposure to asbestos and sex, those exposed as adults had a greater risk of mesothelioma (adjusted HR 2.5, 95% CI 1.7 to 3.7). The slope of the exposure-response relationship did not differ between those exposed as children and those exposed as adults.

Conclusion: We found no greater susceptibility to mesothelioma among those first exposed to asbestos as children than those first exposed as adults. However, given the long latency of mesothelioma, and the greater years of life yet to be lived by the Wittenoom children, it is likely that there will be more cases of mesothelioma in the future among those first exposed as children.

© Author(s) (or their employer(s)) 2018. No commercial re-use. See rights and permissions. Published by BMJ.

In plain English

This cohort study followed 4704 former residents of Wittenoom, a blue asbestos (crocidolite) mining town in Western Australia, who had not worked for the asbestos company, up to December 2014. Of these, 2439 (52%) were first exposed as children under 15. Cumulative exposure was estimated from length of residence and the air levels assigned to each period, but it was missing for 260 residents (5.5%). The mesothelioma rate was lower among those first exposed as children (76.8 per 100 000 person-years) than among those first exposed as adults (121.3 per 100 000). After adjusting for cumulative exposure and sex, those first exposed as adults had a higher risk (hazard ratio 2.51, 95% CI 1.69 to 3.72). The rise in risk with increasing exposure did not differ between the two groups. By the end of follow-up, 12% of the children and 42% of the adults had died, but the numbers of mesothelioma cases were similar. The authors concluded that children did not appear more vulnerable. They expected more future cases among those exposed as children, because of the disease's long latency and their longer remaining lives.

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 of former town residents, linked to death and cancer registries, with follow-up to December 2014
• Who was studied: 4704 former residents of Wittenoom, Western Australia, who lived there between 1943 and 1993 and did not work for the asbestos company. 2439 were first exposed as children (under 15) and 2265 as adults.
• Exposure: Non-occupational exposure to blue asbestos (crocidolite) from living in the town. Residents were assigned airborne levels of 1.0 f/mL for 1943 to 1957 and 0.5 f/mL for 1958 to 1966, falling to 0.010 f/mL by 1992. These levels were combined with duration of residence to estimate cumulative exposure.
• Main results:
  • The mesothelioma rate was 76.8 per 100 000 person-years among those first exposed as children and 121.3 per 100 000 among those first exposed as adults.
  • After adjustment for cumulative exposure and sex, those first exposed as adults had a higher risk of mesothelioma than those first exposed as children (HR 2.51, 95% CI 1.69 to 3.72).
  • Mesothelioma risk increased by 3.1 per 10-fold increase in cumulative exposure (f/mL-years). This exposure-response slope did not differ significantly between the adult-exposed and child-exposed groups (p for interaction 0.58).
  • Children had a higher estimated cumulative exposure than adults: geometric mean 3.02 f/mL-years (IQR 1.40 to 7.70) versus 2.05 f/mL-years (IQR 0.90 to 5.75).
  • Table 1 lists cumulative exposure as missing for 260 of 4704 residents (5.5%): 56 first exposed as children (2.3%) and 204 first exposed as adults (9.01%).
  • By the end of follow-up, 12% of those first exposed as children and 42% of those first exposed as adults had died. The number of mesotheliomas was similar in the two groups: 59 among children and 60 among adults, per Table 1.
  • One comparison involved two groups, both with less than 10 years' residence: those aged 5 or under on arrival, and those aged 20 to 25 at first exposure. The HR for the older group was 4.51 (95% CI 2.32 to 8.75), based on 45 mesotheliomas.
  • In an alternative analysis, people lost to follow-up were censored at the date they were last known to be alive. Rates were higher (103 and 173 per 100 000 in the two age groups), but the adjusted HR for the adult-exposed group was similar (2.57, 95% CI 1.73 to 3.81).
• The authors' conclusion: The authors concluded that children exposed to crocidolite at Wittenoom did not appear more vulnerable to mesothelioma than those exposed as adults. They added that, given the long latency and the children's longer remaining lives, more future cases were highly likely among those first exposed as children.
• Limitations the authors state:
  • Exposure estimates were based on period and duration of residence, not personal monitoring.
  • There was no consistent information on asbestos exposure after leaving Wittenoom.
  • About 20% of the cohort was lost to follow-up.
  • Case numbers were few in the longer time-since-exposure categories, and confidence intervals were wide.
  • The amount and type of exposure at Wittenoom differs markedly from environmental exposures such as those in schools in England.

Topics

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

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

Related studies

• Response to: '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' by Reid et al — A. Farioli, P. Boffetta, et al. (2019)
• Cancer incidence among women and girls environmentally and occupationally exposed to blue asbestos at Wittenoom, Western Australia — A. Reid, J. Heyworth, et al. (2008)
• 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)
• Malignant mesotheliomas in former miners and millers of crocidolite at Wittenoom (Western Australia) after more than 50 years follow-up — G. Berry, A. Reid, et al. (2012)
• Gynecologic and breast cancers in women after exposure to blue asbestos at Wittenoom — A. Reid, A. Segal, et al. (2009)
• 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)

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