Are current or future mesothelioma epidemics in Hong Kong the tragic legacy of uncontrolled use of asbestos in the past?

Our plain-English summary of Are current or future mesothelioma epidemics in Hong Kong the tragic legacy of uncontrolled use of asbestos in the past?, by L.A. Tse, I.T. Yu, W. Goggins, et al (Environmental Health Perspectives, 2010).

The study

• Authors: L.A. Tse, I.T. Yu, W. Goggins, M. Clements, X.R. Wang, J.S. Au, K.S. Yu
• Journal: Environmental Health Perspectives
• Published: 2010;118(3):382-6
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Inhaled asbestos fibers may contribute to three-fourths of malignant mesotheliomas diagnosed in men and almost 40% of cases diagnosed in women. Bans on the manufacture and sale of amphibole asbestos fibers are expected to reduce the incidence of mesothelioma, but the long latency period from initial exposure to clinical disease means that people exposed before bans were enacted will continue to develop asbestos-related mesotheliomas as they age. Tse et al. (p. 382) used historical data on asbestos consumption and mesothelioma diagnoses to predict future mesothelioma trends in Hong Kong. Asbestos use peaked during a construction boom in the early 1960s and subsequently declined by > 90% following a ban on the sale and import of crocidolite and amosite asbestos in 1996, whereas mesothelioma diagnoses in men increased from a single case in 1972–1976 to 63 cases in 2002–2006 (corresponding to crude incidence rates of 0.09 and 3.86 cases/million men, respectively). Assuming an average latency of 42 years, the authors predict that incidence rates will peak in 2009 and that diagnoses will peak in 2014. However, they caution that ongoing use of chrysotile asbestos and the release of asbestos fibers from older buildings during demolition or renovation may slow the projected decline. [corrected]

In plain English

This ecologic study examined mesothelioma in Hong Kong's general population. It used Hong Kong Cancer Registry records and asbestos trade figures (all fiber types combined, per person per year, 1960–2006). From 1976 to 2006, 199 new cases were diagnosed: 137 in males and 62 in females. Among males, the five-year centered moving-average age-standardized incidence rate began rising in 1993–1994, peaked at 3.86 per million in 2004, and was 3.47 per million in 2006. Among females the rise began earlier but was less marked recently. Asbestos use was highest in 1960–1963, averaging 8.84 kg per person per year. Assuming an average 42-year delay between exposure and diagnosis and consumption staying at 2006 levels, the model projected that the male rate would peak in 2009 and male case numbers would peak at 15 per year in 2014. The authors concluded that an epidemic since 2000 paralleled the early-1960s peak in asbestos use. They added that incidence may not fall to background levels, as chrysotile had not been banned. They noted that the trade data did not separate fiber types or cover years before 1960.

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: Ecologic study of registry-based incidence time trends and historical asbestos consumption, with Poisson regression projections for males
• Who was studied: New malignant mesothelioma cases in the Hong Kong general population from the Hong Kong Cancer Registry: 199 cases diagnosed 1976–2006 (137 males, 62 females). Registry data covered 1983–2006, plus three male cases reported earlier.
• Exposure: Estimated local annual consumption of total asbestos (all types, not separated by fiber), taken from import, export and re-export statistics for 1960–2006 and converted to kilograms per person per year. A 1996 law banned the sale and import of crocidolite and amosite; chrysotile continued to be used after 1996. For the projections, exposure after 2006 was assumed to stay at 2006 levels.
• Main results:
  • Among males, the five-year centered moving average of the age-standardized incidence rate peaked in 2004 at 3.86 per million and then fell slightly to 3.47 per million in 2006.
  • Male cases rose from 1 in 1972–1976 to 63 in 2002–2006. The 2002–2006 crude incidence rate for males was 3.86 per million.
  • Among females, the increase began earlier but became less marked in recent years. The male-to-female ratio rose from 0.82 in 1987–1991 to 3.77 in 2002–2006.
  • The highest rates were generally seen in males and females aged 70 years or older.
  • Asbestos consumption was highest in 1960–1963, averaging 8.84 kg per person per year.
  • From 1960 to 2006, per capita asbestos use fell by 93.5% (total import), 96% (total import minus re-export) and 98.5% (total import minus export and re-export). A slight rebound was noted in the mid-1990s.
  • The model projected that the indirectly standardized rate for males would peak in 2009 and that the number of male cases would peak at 15 per year in 2014, assuming asbestos consumption stayed at 2006 levels.
• The authors' conclusion: The authors concluded that Hong Kong has had a mesothelioma epidemic since 2000 that parallels the early-1960s peak in local asbestos consumption. They expected incidence to decline but said it may not return to background levels, because chrysotile has not been banned and secondary environmental exposure will likely continue. They stated that their hypotheses need confirmation by analytic studies, and that the study provides supportive evidence for an immediate global ban on asbestos use.
• Limitations the authors state:
  • There were no data on local asbestos consumption before 1960.
  • The trade statistics did not distinguish between asbestos fiber types.
  • The latency figures used (mean 42 years, standard deviation 10.5 years) came from other studies and might not exactly describe latency in Hong Kong.
  • Too few female cases were available to build a projection model for females, and the number of male cases was also small.
  • Because this was an ecologic study, its hypotheses need confirmation by later analytic studies.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Malignant Mesothelioma, Amphibole Asbestos, Latency, Crocidolite, Amosite, Incidence, Chrysotile.

Related studies

• Mesothelioma and lung cancer mortality: a historical cohort study among asbestosis workers in Hong Kong — M. Chen, L.A. Tse, et al. (2012)
• History of Asbestos Ban in Hong Kong — C.K. Wong, S.H. Wan, et al. (2017)
• Malignant mesothelioma in Hong Kong — K.C. Chang, C.C. Leung, et al. (2006)
• Asbestos fiber burdens in lung tissues of Hong Kong Chinese with and without lung cancer — Y. Liu, P. Zhang, et al. (2001)
• Past and current asbestos exposure and future mesothelioma risks in Britain: The Inhaled Particles Study (TIPS) — C. Gilham, C. Rake, et al. (2018)
• Commentary: Past and current asbestos exposure and future mesothelioma risks in Britain — B. Terracini (2018)

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