24 years of pneumoconiosis mortality surveillance in Australia

Our plain-English summary of 24 years of pneumoconiosis mortality surveillance in Australia, by D.R. Smith, P.A. Leggat (Journal of Occupational Health, 2006).

The study

• Authors: D.R. Smith, P.A. Leggat
• Journal: Journal of Occupational Health
• Published: 2006;48(5):309-13
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestosis, silicosis and Coal Worker's Pneumoconiosis (CWP) represent three of the most important occupationally-related dust diseases in Australia. To gain a clear picture of pneumoconiosis trends over time, a 24-yr retrospective analysis of national mortality data was performed for the period 1979 to 2002. Over 1,000 pneumoconiosis-related fatalities occurred during this time, 56% of which were caused by asbestosis, 38% by silicosis and 6% by CWP. Between 1979 and 1981, silicosis accounted for 60% of all pneumoconiosis-related fatalities in Australia, followed by asbestosis (31%). By 2002 however, asbestosis was causing 78% of all fatalities, while silicosis accounted for only 19%. Asbestos-related mortality increased three-fold between 1979 and 2002, with a clear excess risk demonstrated among males. On the other hand, mortality rates for silicosis and CWP declined significantly during the same time period. Overall, this study suggests that pneumoconiosis, particularly asbestosis, continues to be an important occupational disease in Australia. Although progress has been made in reducing deaths due to occupational silicosis and CWP, asbestosis rates continue to rise, reflecting the long latency between dust exposure and clinical disease. Countries which continue to use asbestos products in the workplace should note the tragic legacy of this material within contemporary Australia.

In plain English

This study looked at deaths from three dust-related lung diseases in Australia's national death records from 1979 to 2002: asbestosis, silicosis and coal worker's pneumoconiosis (CWP). The authors counted deaths coded to each disease, grouped them into three-year blocks, and calculated crude death rates per million people. Over 1,000 such deaths were recorded. Of these, 99% were male, 56% were from asbestosis, 38% from silicosis and 6% from CWP. In 1979–1981 silicosis caused 60% of these deaths and asbestosis 31%. By 2002 asbestosis caused 78% and silicosis 19%. The crude asbestosis death rate among males peaked at 5.3 per million in 2000–2002, against 0.1 per million among females. Measured as a mortality odds ratio with females as the reference group, males' overall risk of asbestosis death was 6.5 (95% CI 5.6 to 7.7). Silicosis and CWP death rates fell over the period. The authors concluded that asbestosis continues to be an important occupational disease in Australia, with rising rates reflecting the long delay between dust exposure and disease. They noted that improved reporting may affect comparisons with earlier data.

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 analysis of national mortality (death-record) data
• Who was studied: All deaths in Australia from 1979 to 2002 coded as coal workers' pneumoconiosis, asbestosis or silicosis, taken from the Australian Bureau of Statistics national mortality data set. There were over 1,000 deaths in total, and rates were calculated against the total Australian population.
• Exposure: Deaths were classified by disease code: pneumoconiosis due to asbestos dust (asbestosis), pneumoconiosis due to silica dust (silicosis), and coal workers' pneumoconiosis. The study did not look at individual exposure data, fiber types or jobs.
• Main results:
  • Of over 1,000 pneumoconiosis deaths in 1979–2002, 99% were male. 56% were from asbestosis, 38% from silicosis and 6% from CWP.
  • In 1979–1981, silicosis accounted for 60% of pneumoconiosis deaths and asbestosis for 31%.
  • By 2002, asbestosis accounted for 78% of pneumoconiosis deaths and silicosis for 19%.
  • The article's abstract reports that asbestos-related mortality increased three-fold between 1979 and 2002.
  • The crude asbestosis death rate among males peaked at 5.3 per million in 2000–2002. Among females it was 0.1 per million in the same period.
  • The authors measured males' risk of asbestosis death against females (reference = 1.0) as a mortality odds ratio. It ranged from 5.1 to 7.4 across periods, with an overall figure of 6.5 (95% CI: 5.6 to 7.7). The results section labels this figure 'relative risk'.
  • The overall figure for males compared with females was 6.5 (95% CI: 5.6 to 7.7).
  • The crude silicosis death rate (whole population) fell from 1.8 per million in 1982–1984 to 0.5 per million in 1997–1999.
  • The crude silicosis death rate among males fell from 3.6 per million in 1982–1984 to 1 per million in 1997–1999.
  • The crude CWP death rate fell from 0.6 per million (males) and 0.3 per million (both genders) in 1988–1990 to 0.1 per million (males) and 0.07 per million (both genders) in 1994–1996.
• The authors' conclusion: The authors concluded that pneumoconiosis, particularly asbestosis, continues to be an important occupational disease in Australia. They found that deaths from silicosis and CWP have been reduced but asbestosis rates continue to rise, and they attributed the rise to the long latency between dust exposure and disease.
• Limitations the authors state:
  • The statistics bureau's privacy policy on small numbers meant single-year death counts were unavailable, so deaths were combined into 3-year blocks.
  • Data from before 1979 could not be compared because earlier coding had overlapping disease categories.
  • Deaths from CWP were few when counted by single years.
  • Disease reporting has improved in recent years. This raises an issue of comparability with earlier data, in which asbestos-related disease was probably underestimated.

Topics

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Silicosis, Occupational Disease, Latency.

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