Exposures estimates of the Wittenoom mining workforce and town residents - Implications associated with risk estimation for persons exposed to asbestiform riebeckite

Our plain-English summary of Exposures estimates of the Wittenoom mining workforce and town residents - Implications associated with risk estimation for persons exposed to asbestiform riebeckite, by A.J. Rogers (Toxicology and Applied Pharmacology, 2018).

The study

• Author: A.J. Rogers
• Journal: Toxicology and Applied Pharmacology
• Published: 2018;361:168-170
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The mining of crocidolite at Wittenoom from 1943 to 1966 is infamous due to the adverse health outcomes in the mining and milling workforce and the non-mining residents and families. Proportional latency risk analysis provided estimates that 6% of the mine workforce along with 1.9% of women and 1.1% of children residents who were environmentally exposed, have or will die from mesothelioma. The absence of environmental exposure data relevant to the period restricts the extrapolation of these historical risk outcomes being applied to the low level exposures from natural contaminant crocidolite and other amphibole fibres experienced in contemporary mining practices in the Pilbara region.

Copyright © 2018. Published by Elsevier Inc.

In plain English

This short article by a single author was a commentary that reviewed historical dust measurements from the Wittenoom crocidolite mine, mill and town in Western Australia, where mining ran from 1943 to 1966. It was not a new study of disease. Mines Inspectorate konimeter surveys recorded average particle counts of 155 to 685 ppcc underground (n = 605) and 200 to 1000+ ppcc for fibre treatment and bagging in the mill (n = 207). The only direct airborne fibre survey, in 1966, recorded 270 fibres/cc longer than 5 micrometres for mill plant operators and 20 for miners. No airborne monitoring was done in residential areas before the mine closed, and the author reported that later town surveys from 1973 to 1978 had deficiencies. The author judged there was not enough information to calculate workers' cumulative fibre doses. The author also argued that the exposure "guestimates" used in earlier risk studies most likely produced a lower risk coefficient for crocidolite. In current Pilbara iron ore mining, the cited measurements were under 5% of a shift-adjusted standard of 0.07 fibres/cc for equipment operators and blast crew, and 10% for drill operators. The author concluded that the lack of exposure data from the mining period limits applying Wittenoom's historical risks to today's low-level exposures.

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: Commentary / narrative review of historical and contemporary dust monitoring data and of exposure estimates used in earlier studies
• Who was studied: The mining and milling workforce and town residents of Wittenoom, Hamersley Ranges, Western Australia (crocidolite mining 1943 to 1966), plus workers in contemporary Pilbara iron ore mining
• Exposure: Crocidolite (asbestiform riebeckite) dust from mining, crushing, milling and bagging; tailings (1% crocidolite) used in residential areas; naturally occurring crocidolite and other amphibole fibres in contemporary mining
• Main results:
  • Inspectorate konimeter surveys (particle counts, not fibre counts) for workplaces: underground n = 605, range of averages 155 to 685 ppcc; primary picking and crushing n = 107, range of averages 120 to 510 ppcc; fibre treatment and bagging in the mill n = 207, range 200 to 1000+ ppcc
  • In the 1966 survey by Major, fibre counts (fibres longer than 5 micrometres per cc) were 270 for mill plant operators, 80 to 100 for bagging operators, 10 to 20 for crusher and picking belt workers, and 20 for miners
  • The author judged that there was insufficient exposure information to estimate fibre exposures or cumulative dose for Wittenoom workers in a scientific manner
  • The author argued that dose-response studies by Hodgson and Darnton and by Berman and Crump relied on exposure guestimates rather than measurements for Wittenoom workers, which most likely produced a lower risk coefficient for crocidolite
  • For town residents, no airborne monitoring was done in residential areas before the mine closed in late 1966. In 1973, mean concentrations were 0.4 f/ml when grading roadsides and driving around town and 0.05 f/ml at relatively undisturbed town sites
  • Residents wearing personal samplers in 1978 had exposures of 0.01 fibres/cc or less, up to 0.2 f/cc for those actively disturbing residual tailings
  • In a cited contemporary Pilbara iron ore mine study, exposures of heavy mobile equipment operators and the blast crew were under 5% of the 12-hour shift-adjusted standard of 0.07 fibres/cc, and those of drill operators were 10% of it
• The authors' conclusion: The author concluded that exposure assessment at Wittenoom was very limited, that exposure profiles cannot be determined, and that the absence of exposure data from the period limits applying the historical risk outcomes to low-level exposures in contemporary mining
• Limitations the authors state:
  • The author noted technical deficiencies in the historical dust sampling and a wide spread of values that made trends difficult to resolve
  • The author stated that the residential surveys from 1973 onward had deficiencies, were unrepresentative and used inappropriate techniques
  • The author noted that counting small numbers of fibres among host rock particles adds statistical uncertainty to contemporary measurements

Topics

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

Medical terms in this study, explained in our Lexicon: Wittenoom, Asbestiform, Riebeckite, Crocidolite, Latency, Mesothelioma, Environmental Exposure, Amphibole Group.

Related studies

• Environmental pleural plaques in residents of a Quebec chrysotile mining town — A. Churg, L. DePaoli (1988)
• Determining satisfaction with access and financial aspects of care for persons exposed to Libby amphibole asbestos: rural and national environmental policy implications — C.A. Winters, W. Hill, et al. (2011)
• Sputum asbestos bodies and radiographic changes in residents of Wittenoom, Western Australia — A.W. Musk, J.E. Baker, et al. (1983)
• Risk assessment due to environmental exposures to fibrous particulates associated with taconite ore — R. Wilson, E.E. McConnell, et al. (2008)
• 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)

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