Additional Australia Mesothelioma Data
Mesothelioma data collection in Western Australia
The W.A. Mesothelioma Register
The W.A. Mesothelioma Register had its beginnings in a number of case lists maintained in various Branches of the Department of Public Health. The register maintained in the Occupational Health, Clean Air and Noise Abatement Branch was the first in Australia. The Register as it is currently known was commenced in June 1976 after amalgamation of the two main sources. At that time, moves towards a national mesothelioma surveillance program highlighted the need for a case review committee in each State, and the first meeting of the W.A. Mesothelioma Register Committee was held in December 1978.The information collected for each case increased over time, from simple descriptive summary data through various questionnaires administered by persons at the Medical Centre, the Department of Occupational Health, Safety and Welfare of Western Australia (DOHSWA - now Worksafe Western Australia) and the Department of Health (WA). In 1986, responsibility for mesothelioma data collection and the Register was transferred to the Western Australian Cancer Registry.
Notification and recording of malignant mesothelioma cases
In Western Australia, reporting of cancer cases by pathologists is mandatory, and governed by the Health (Notification of Cancer) Regulations 1981 (see Appendix 2E). Many cases are notified by pathologists, but some first come to the Register's attention via death certificates, and some via treating physicians.Mesothelioma Register Committee
The Mesothelioma Register Committee meets periodically to consider collected information about probable mesothelioma cases, with a view to determining whether they should be confirmed as a WA case on the Mesothelioma Register, excluded as non-mesothelioma or non-WA resident, or given "suspected" status when a definitive decision cannot be made and no more information is ever likely to be found. Current members of the Committee include a pathologist, a respiratory physician, an occupational health physician, an epidemiologist, the Register's research officer, and the Principal Medical Officer of the Western Australian Cancer Registry.Types of cases recorded on the Register
The Mesothelioma Register contains information on persons who were, at some time, considered likely to have malignant mesothelioma. A Confirmation Status field on the Register records the outcome of the case review process at any time, and the workload associated with the investigation of many cases that are not eventually confirmed, is considerable. The confirmation status flags shown in the following table determine the handling of cases; only Confirmed cases contribute towards incidence statistics. "Suspected" and "Excluded" cases remain on the Register only for efficiency, in case of new information such as that from a death certificate, which might otherwise lead to duplication of previous investigative work.Mesothelioma Register Confirmation Status codes
Status | Meaning |
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Confirmed |
Confirmed to have malignant mesothelioma diagnosed while resident in Western Australia. Subsequent change of status of these cases is unusual. |
Suspected | Cases for which available evidence cannot support either confirmation or exclusion, and for which no further information is likely to become available. |
Non-mesothelioma | Cases have been determined after review to have had a more appropriate diagnosis for their condition, which in most cases has been a lung carcinoma. |
Unpresented | Cases in the early stages of the case review process, for whom review is planned and for whom data collection is proceeding. |
Excluded | Cases with mesothelioma, diagnosed while resident elsewhere than in Western Australia. |
Pending | Cases have been reviewed, decision unclear, and better information is being sought. Most are eventually confirmed. |
The Mesothelioma Register Committee's work continues to include the resolution of old cases with a "probable" status which have come to its attention in recent years. Consequently, the number of cases confirmed in any one year may be greater than the number of cases diagnosed in that year. For example, in 1993 84 Western Australian malignant mesothelioma cases were confirmed compared to 69 cases diagnosed. More recent figures in the following table show variation in workload from year to years, with 2002 being a particularly busy year in terms of earlier-diagnosed cases that were reviewed and confirmed.
Mesothelioma cases confirmed and cases diagnosed by year, 1999-2004
Between 1995 and early 2004, while the number of Confirmed cases on the Register more than doubled, the "Suspected" cases increased by only 25%, and "Non-mesothelioma" numbers increased by a factor of 3.5 - indicating not only more suspicions being reported, but also a higher success rate in resolving the diagnosis, often with newer pathology techniques.
Status of cases on the WA Mesothelioma Register, 1995 and 2005
Significant asbestos exposure
The Register database records an assessment of each case's likely source of asbestos exposure leading to their mesothelioma, as determined by the Mesothelioma Register Committee. (Inherent in this process is a generally-accepted a priori assumption that mesothelioma is caused by asbestos exposure until shown otherwise.)These assessments take into account information from all available sources, including duration of various employment and residential situations, and intensity of asbestos exposure. The codes assigned are, in principle, independent of each person's "main" lifetime occupation. In this sense, these assessments differ from some earlier hierarchical case-classification schemes, in which relative duration or intensity of exposure was not taken into account.
"Significant" exposure codes and categories used in the WA Mesothelioma Register
Code | Asbestos exposure history |
U | Unknown exposure: This includes persons with inadequate history from which to assess the likely risk from their residence or occupational exposures. |
N | No exposure to asbestos: Persons with a history which appears sufficient to eliminate contact with known sources of possible asbestos exposure. |
R1 | Wittenoom resident, not employed: Residents of Wittenoom who had residential exposure rather than occupational exposure. |
R2 | Wittenoom visitor: Non-occupational exposure while temporarily in Wittenoom. |
R3 | Non-Wittenoom resident, family contact with asbestos: Persons with contact with asbestos through other family members, e.g. contaminated clothing. |
R4 | DIY handyman exposure: This includes those thought to have been exposed during home repair or renovation work. |
R5 | Other residential exposure: Exposure by virtue of place of residence, not related to nature of employment. |
W1 | Asbestos mining company employees, Wittenoom: Exposure as an employee of the company operating the asbestos mine at Wittenoom, whether directly involved in mining operations or not. |
W2 | Non-mining company employees at Wittenoom: Exposure while employed in Wittenoom, including contractors at the asbestos mine. |
W3a | Western Australian railway workers: Exposure during railway work, including workshop exposure during repair and maintenance of brakes and insulation materials. |
W3b | Non-WA railway workers: Railways-related exposure outside Western Australia. |
W4 | Asbestos cement manufacture: Exposure during the mixing, moulding and trimming of asbestos cement products. |
W5 | Wharf workers, Point Samson: Exposure during asbestos storage and loading operations at the primary sea terminal for asbestos transport from the mines at Wittenoom. |
W6 | Wharf workers, Fremantle: Asbestos exposure during unloading and general asbestos handling at Fremantle, the main international sea port in Western Australia. |
W7 | Wharf workers, other or unspecified: Exposure during asbestos handling at unspecified locations. |
W8/18 | Asbestos insulation & lagging manufacturers/users: Exposure during manufacture and application of asbestos-containing insulation coatings, including spray-on mixtures. |
W9 | Asbestos transport and loading, non-wharf workers: Includes persons employed in road transport of asbestos, mainly in North-West Western Australia. |
W10 | Building, construction and supply workers: Users and handlers of asbestos as an end-use product for the building trade. |
W11 | Armed forces: Exposure to asbestos, usually as an insulation and fireproofing coating, common especially in naval ships. |
W12 | Plumbers: Exposure to asbestos as used for pipe insulation and gaskets. |
W13 | Asbestos mining workers, other: Exposure to asbestos in asbestos mining situations other than the mine at Wittenoom. |
W14 | Non-asbestos mining workers: Mine workers in gold mines and others where asbestos found as a contaminant rather than as the mineral of economic interest. |
W15 | Other occupational exposure: Thought to have asbestos exposure in occupational settings not included in other categories in this list. |
W16 | Automotive or other brake material exposure: Brake lining exposure in manufacturers or repairers, including maintenance work on mining machinery. |
W17 | Pipe fitters: Pipe-lagging and gasket exposure. |
W19 | Boiler makers, cleaners and welders: Asbestos lagging and insulation exposure during manufacturing or maintenance procedures. |
W20 | Shipbuilding industry: Use of asbestos for heat and sound insulation. |
W21 | Power station workers: Contact with asbestos insulation. |
W22 | Electricians and electrical fitters: Contact with asbestos insulation. |
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Significant asbestos exposure groupings: occupational vs nonoccupational and raw vs processed asbestos exposure
Code | Meaning | ||
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W1 | Work – asbestos mining company employees, Wittenoom | ||
WR | Work – raw asbestos | ||
WP | Work – processed asbestos (end-use) | ||
WQ | Work – other/unknown | ||
RR | Residential exposure – raw asbestos | ||
RP | Residential exposure- processed asbestos | ||
RQ | Residential exposure – other/unknown | ||
N | |||
U | Unknown asbestos exposure | ||
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Significant asbestos exposure: activity-based groupings
Code | Meaning |
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W | Asbestos mining & milling |
B | Building construction & supply |
I | Insulation / lagging work |
M | Asbestos cement manufacture |
T | Asbestos transport |
O | Other |
N | |
U | Unknown asbestos exposure |
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Mesothelioma, Western Australia: incidence and mortality, males, 1960 - 2003
Mesothelioma, Western Australia: incidence and mortality, females, 1960 - 2003
Mean and median age at diagnosis of mesothelioma, Western Australia 1960-2003, for males and females
Mesothelioma, Western Australia, 1960-2003: age at diagnosis
Mean and median "lead time" between first asbestos exposure and mesothelioma diagnosis
Presumed source of significant asbestos exposure
Commercial asbestos mining was in progress at Wittenoom from 1943 to 1966, and most cases in earlier years of the period shown were associated with this exposure source. In more recent years however, exposure due to other occupations has contributed more to the total number of cases diagnosed each year, in particular the building and construction industry.The non-occupational exposure categories include people who were exposed through handyman-type work at home or who were exposed to asbestos as residents of Wittenoom. The latter make up the biggest group within the non-occupational category. For a minority of confirmed cases (73 out of a total of 1174), review of a full occupational and residential history suggested that there has been no exposure to asbestos. For a significant number of cases (122 of 1174, or 10%), there is insufficient information to determine type of exposure, but none was reported.
The most common individual significant asbestos exposure category over the 1960-2003 period remains that relating to ABA (Australian Blue Asbestos) employment at Wittenoom, with 204 male and 10 female cases attributed. The building construction/supply industry exposure category was the next most common code, followed by "No known asbestos exposure".
Significant asbestos exposure categories and confirmed mesothelioma cases, Western Australia, 1960 - 2003
For the most recent ten years (1994-2003), the most common specific exposure categories are shown in Figures 22 and 23. Among 569 mesothelioma cases occurring in males, those associated with the building and construction industry (20%) now outnumber those directly related to asbestos-related work at Wittenoom (15%). Cases without known asbestos exposure comprised 8% of all cases, and 3% of cases were thought to have had no asbestos exposure.
Among the 81 female cases in the 10 year period, the Unknown exposure (25%) and No exposure cases (22%) were the most common categories. Among females, the four most common specific asbestos exposure categories were all non-occupational: residential exposure in Wittenoom (14%), non-occupational building/handyman exposure (9%), "other" residential exposure, and "family contact" exposure such as washing an asbestos-worker's clothes.
Mesothelioma, Western Australia, males 1994-2003 (569 cases): Most common significant asbestos exposure categories
Mesothelioma, Western Australia, females 1994-2003 (81 cases): Most common significant asbestos exposure categories
Over the entire period 1960-2003, 869 mesothelioma cases (74 % of the total) were thought to have been due to occupational asbestos exposure. Non-occupational (mostly residential) exposure accounted for 9% of cases, 6% were thought not to have had any asbestos exposure, and 10% of cases lacked sufficient information for a determination. At this level of grouping, there have been no consistent trends over the time periods examined. However, the number of cases associated with asbestos exposures while working for the mining company at Wittenoom, has decreased from 32% in 1960-87 to 11 – 12% since 1998.
The main changes shown in the following are a decline in the number of cases with exposures thought to be related to raw or unprocessed asbestos, from 51% in 1960-1987, to 24% in 2001-2003 - with a corresponding increase in cases thought to be associated with "end uses" of asbestos products.
Significant asbestos exposure, Western Australian mesothelioma cases, 1960-2003: occupational vs nonoccupational and raw vs processed asbestos exposure
Mesothelioma, Western Australia, 1984-2003: trends in significant asbestos exposure type
