Asbestosis mortality in the USA: facts and predictions

Our plain-English summary of Asbestosis mortality in the USA: facts and predictions, by V.C. Antao, G.A. Pinheiro, J.T. Wassell (Occupational and Environmental Medicine, 2009).

The study

• Authors: V.C. Antao, G.A. Pinheiro, J.T. Wassell
• Journal: Occupational and Environmental Medicine
• Published: 2009;66(5):335-8
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Mortality trends in the USA show that deaths from asbestosis are increasing, while deaths related to other pneumoconiosis are declining.

Objectives: To analyse the association between asbestos consumption and asbestosis mortality trends.

Methods: In an epidemiological time series study, we used a modern computer-intensive local regression method to evaluate the relationship between asbestos consumption per capita (1900-2006) as the predictor variable and number of deaths from asbestosis (1968-2004). The predictor variable was progressively lagged by annual increments from 30 to 60 years and the goodness of fit assessed for each lag period. The model having the smallest Akaike's Information Criteria was used to derive extrapolated estimates of future mortality based on more recent asbestos consumption data.

Results: Asbestos consumption per capita reached a peak in 1951 and gradually declined until 1973, when it started to drop rapidly. In 2006, it was 0.0075 kg/person/year. There were 25 564 deaths from asbestosis over the period 1968-2004. The best-fitting model (adjusted coefficient of determination (R(2)) = 99.7%) for 1968-2004 deaths from asbestosis used asbestos consumption per capita 48 years prior (1920-1956) and the log value of asbestos consumption per capita 43 years prior (1925-1961). This model predicts a total of 29 667 deaths (95% CI 19 629 to 39 705) to occur during 2005-2027 (an average of 1290 deaths per year).

Conclusions: This study demonstrates a clear association between asbestos consumption and deaths from asbestosis and indicates that asbestosis deaths are not expected to decrease sharply in the next 10-15 years.

In plain English

This ecological time-series study asked whether past US asbestos use tracked later deaths from asbestosis. The authors used national asbestos consumption per person (1900 to 2006) as a stand-in for exposure. They compared it with death-certificate records listing asbestosis as an underlying or contributing cause among US residents aged 15 and older from 1968 to 2004. Consumption peaked at 4.7 kg per person per year in 1951 and was 0.0075 kg per person per year in 2006. There were 25 564 asbestosis deaths, 96.2% of them in males. Yearly deaths rose from 68 in 1968 to 1493 in 2000 and stayed stable through 2004. The best-fitting model linked deaths to consumption 48 and 43 years earlier. It predicted 29 667 deaths (95% CI 19 629 to 39 705) during 2005 to 2027, an average of 1290 per year. The authors concluded there was a clear association and that asbestosis deaths are not expected to decrease sharply in the next 10 to 15 years. They noted that consumption may not reflect individuals' exposure, that fiber type was not modelled, and that predictions are tenuous.

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: Ecological (population-level) time-series study using a generalised additive statistical model; asbestos consumption served as a surrogate for exposure
• Who was studied: Asbestosis deaths recorded on US death certificates (as underlying or contributing cause) among US residents aged 15 years and older, all states combined, 1968 to 2004: 25 564 deaths
• Exposure: National apparent asbestos consumption per person in the USA, 1900 to 2006, from US Geological Survey data. It was used as a surrogate for exposure and was not broken down by fiber type.
• Main results:
  • US asbestos consumption per person peaked at 4.7 kg/person/year in 1951, then declined
  • US asbestos consumption in 2006 was 0.0075 kg/person/year
  • There were 25 564 asbestosis deaths recorded in 1968 to 2004
  • Of the 25 564 asbestosis deaths, 8488 (33%) had asbestosis recorded as the underlying cause of death
  • Of the 25 564 decedents, 96.2% were male and 93.5% were white
  • Annual US asbestosis deaths rose from 68 in 1968 to a peak of 1493 in 2000 and remained stable through 2004
  • The best-fitting model (adjusted R2 = 99.7%) for 1968 to 2004 asbestosis deaths used consumption per person 48 years earlier and the log of consumption per person 43 years earlier
  • The model predicted a total of 29 667 US asbestosis deaths (95% CI 19 629 to 39 705) during 2005 to 2027
  • The predicted deaths during 2005 to 2027 average 1290 per year
• The authors' conclusion: The authors concluded that there is a clear association between asbestos consumption and asbestosis deaths as reported on death certificates. They also concluded that asbestosis deaths are not expected to decrease sharply in the next 10 to 15 years.
• Limitations the authors state:
  • It is an ecological study, so asbestos consumption may not reflect each individual's actual exposure
  • Number of people exposed, level and duration of exposure, and type of asbestos are not on death certificates and were not included in the model
  • Lower exposure levels after the 1970s, shorter exposure durations and fewer amphibole imports after the 1980s mean the predictions may overestimate mortality
  • Other factors may lead to underestimated predictions, such as exposure during demolition and maintenance of past asbestos installations, which is not captured in consumption figures
  • Mortality data are subject to errors in diagnosis, recording and coding
  • Changes between ICD code versions may matter. The ICD-10 code covers pneumoconiosis due to asbestos and other mineral fibers, which may have increased recorded cases.
  • Future predictions are tenuous and may be biased by unobserved covariates
  • Predictions after 2027 use consumption values outside the range used to fit the model and are shown only for illustration

Topics

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

Medical terms in this study, explained in our Lexicon: Pneumoconiosis.

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