Preparing an estimate of the national pattern of exposure to asbestos in cases of malignant mesothelioma JULY 2008
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TABLE OF CONTENTS TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES BACKGROUND OF THE PROJECT TEAM BACKGROUND OF THE PROJECT TEAM ACKNOWLEDGEMENTS GLOSSARY EXECUTIVE SUMMARY ii iv vi viii viii viii ix x 1. INTRODUCTION 1 1.1 Background 1 1.2 Project aims 2 1.3 Outline of the structure of the report 2 2. REVIEW OF AVAILABLE DATA 3 2.1 Introduction 3 2.2 The Australian Mesothelioma Register 3 2.3 The National Cancer Statistics Clearing House 4 2.4 The New South Wales Dust Disease Board Data 4 2.5 The Western Australian Mesothelioma Register 5 2.6 The National Coroners Information System 6 Methods 7 Results 7 Discussion 10 2.7 Other potentially useful data sources 11 Asbestos use 11 Occupation and industry 15 Legal sources 15 2.8 Consideration of the completeness of coverage of the data sources 15 3. FEASIBILITY OF PRODUCING AN ON-GOING DIRECT NATIONAL ESTIMATE OF TRENDS IN EXPOSURE TO ASBESTOS USING AVAILABLE DATA 19 4. ANALYSIS OF TRENDS IN ASBESTOS EXPOSURE IN MESOTHELIOMA CASES RECORDED IN THE WESTERN AUSTRALIA REGISTER 21 4.1 Overall analysis 21 Age and sex 21 Latency 22 Year of diagnosis 23 Source of asbestos exposure 23 Year of first exposure 25 Asbestos exposure patterns and mesothelioma...june 2008 ii
4.2 Changes in case characteristics over time 26 Age and sex 26 Latency 27 Source of exposure 27 5. ANALYSIS OF TRENDS IN ASBESTOS EXPOSURE IN MESOTHELIOMA CASES RECORDED IN THE NEW SOUTH WALES DUST DISEASES BOARD DATABASE 31 5.1 Overall analysis 31 Age and sex 31 Year of diagnosis 32 Latency 33 Source of asbestos exposure 34 Source of asbestos exposure 34 Year of first exposure 38 5.2 Changes in case characteristics over time 39 Age and sex 39 Latency 40 Source of exposure 41 5.3 Analysis using all records 44 Year of first exposure for each job 44 Source of asbestos exposure 45 Changes over time in all jobs 49 6. DISCUSSION 52 6.1 Overview 52 6.2 Future approaches to monitoring malignant mesothelioma in Australia 53 7. SUMMARY 55 Asbestos exposure patterns and mesothelioma...june 2008 iii
LIST OF TABLES Table 2.1 Deaths due to malignant mesothelioma Victoria, 2004 and 2005 AIHW versus NCIS. 8 Table 2.2 Mention of asbestos exposure circumstances in NCIS documents for deaths due to malignant mesothelioma Victoria, 2004. 9 Table 2.3 Asbestos Production Australia. 13 Table 2.4 Asbestos Imports Australia. 13 Table 2.5 Asbestos Apparent Consumption. 14 Table 2.6 Incident cases of malignant mesothelioma reported by the National Cancer Statistics Clearing House. Number. 16 Table 2.7 Incident cases of malignant mesothelioma reported by the NSW Dust Diseases Board, Western Australia Mesothelioma register and Australian Mesothelioma Register. Number. 17 Table 2.8 Incident cases of malignant mesothelioma reported by NSW Dust Diseases Board, Western Australia Mesothelioma register and Australian Mesothelioma Register. Per cent of cases reported by National Cancer Statistics Clearing House. 18 Table 4.1 Age at diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 21 Table 4.2 Latency. Mesothelioma cases in Western Australia, 1960 2004. 22 Table 4.3 Year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 23 Table 4.4 General source of asbestos exposure. Mesothelioma cases in Western Australia, 1960 2004. 23 Table 4.5 Specific source of asbestos exposure. Mesothelioma cases in Western Australia, 1960 2004. 24 Table 4.6 Year of first exposure to asbestos. Mesothelioma cases in Western Australia, 1960 2004. 25 Table 4.7 General source of asbestos exposure by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 27 Table 4.8 Wittenoom versus non-wittenoom (workers and residents) by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 28 Table 4.9 Main individual sources of asbestos exposure by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 29 Table 5.1 Age at diagnosis. Mesothelioma cases in New South Wales, 1962 2004. 31 Table 5.2 Year of diagnosis. Mesothelioma cases in New South Wales, 1962 2004. 32 Asbestos exposure patterns and mesothelioma...june 2008 iv
Table 5.3 Latency. Mesothelioma cases in New South Wales, 1962 2004. 33 Table 5.4 Broad occupation at time of first exposure. Mesothelioma cases in New South Wales, 1962 2004. 34 Table 5.5 Occupation sub-categories at time of first exposure to asbestos. Mesothelioma cases in New South Wales, 1962 2004. 35 Table 5.6 Specific occupation at time of first exposure to asbestos. Mesothelioma cases in New South Wales, 1962 2004. 36 Table 5.7 Industry at time of first exposure. Mesothelioma cases in New South Wales, 1962 2004. 37 Table 5.8 Year of first exposure to asbestos. Mesothelioma cases in New South Wales, 1962 2004. 38 Table 5.9 Main occupation categories during first asbestos exposure by year of diagnosis. Mesothelioma cases in New South Wales, 1960 2004. 41 Table 5.10 Main industry during first asbestos exposure by year of diagnosis. Mesothelioma cases in New South Wales, 1960 2004. 42 Table 5.11 Year of first exposure to asbestos all jobs. Mesothelioma cases in New South Wales, 1962 2004. 44 Table 5.12 Broad occupation at time of first exposure all jobs. Mesothelioma cases in New South Wales, 1962 2004. 45 Table 5.13 Occupation sub-categories at time of first exposure to asbestos all jobs. Mesothelioma cases in New South Wales, 1962 2004. 46 Table 5.14 Specific occupation at time of first exposure to asbestos all jobs. Mesothelioma cases in New South Wales, 1962 2004. 47 Table 5.15 Industry at time of first exposure all jobs. Mesothelioma cases in New South Wales, 1962 2004. 48 Table 5.16 Main occupation categories for all asbestos exposures by year of diagnosis. Mesothelioma cases in New South Wales, 1960 2004. 49 Table 5.17 Main industry for all asbestos exposures by year of diagnosis. Mesothelioma cases in New South Wales, 1960 2004. 50 Asbestos exposure patterns and mesothelioma...june 2008 v
LIST OF FIGURES Figure 2.1 Asbestos Consumption in Australia 1900-1985. 14 Figure 4.1 Age at diagnosis. Mesothelioma cases in Western Australia, 1960 2004 21 Figure 4.2 Latency. Mesothelioma cases in Western Australia, 1960 2004 22 Figure 4.3 Year of first exposure to asbestos. Mesothelioma cases in Western Australia, 1960 2004. 25 Figure 4.4 Gender by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 26 Figure 4.5 Mean age at diagnosis by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 26 Figure 4.6 Mean latency by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 27 Figure 4.7 General source of asbestos exposure by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 28 Figure 4.8 Wittenoom versus non-wittenoom (workers and residents) by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004. 29 Figure 4.9 Main individual sources of asbestos exposure by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004 (Number). 30 Figure 4.10 Main individual sources of asbestos exposure by year of diagnosis. Mesothelioma cases in Western Australia, 1960 2004 (Per cent). 30 Figure 5.1 Age at diagnosis. Mesothelioma cases in New South Wales, 1962 2004 32 Figure 5.2 Latency. Mesothelioma cases in New South Wales, 1960 2004 33 Figure 5.3 Year of first exposure to asbestos. Mesothelioma cases in New South Wales, 1962 2004. 38 Figure 5.4 Gender by year of diagnosis. Mesothelioma cases in New South Wales, 1962 2004. 39 Figure 5.5 Mean age at diagnosis by year of diagnosis. Mesothelioma cases in New South Wales, 1962 2004. 40 Figure 5.6 Mean latency by year of diagnosis. Mesothelioma cases in New South Wales, 1962 2004. 40 Figure 5.7 Main occupation categories during first asbestos exposure by year of diagnosis. Mesothelioma cases in New South Wales, 1970 2004 (Number). 41 Figure 5.8 Main occupation categories during first asbestos exposure by year of diagnosis. Mesothelioma cases in New South Wales, 1970 2004 (Per cent). 42 Asbestos exposure patterns and mesothelioma...june 2008 vi
Figure 5.9 Main industry during first asbestos exposure by year of diagnosis. Mesothelioma cases in New South Wales, 1970 2004 (Number). 43 Figure 5.10 Main industry during first asbestos exposure by year of diagnosis. Mesothelioma cases in New South Wales, 1970 2004 (Per cent). 43 Figure 5.11 Year of first exposure to asbestos all jobs. Mesothelioma cases in New South Wales, 1962 2004. 45 Figure 5.12 Main occupation categories for all asbestos exposures by year of diagnosis. Mesothelioma cases in New South Wales, 1970 2004 (Number). 49 Figure 5.13 Main occupation categories for all asbestos exposures by year of diagnosis. Mesothelioma cases in New South Wales, 1970 2004 (Per cent). 50 Figure 5.14 Main industry for all asbestos exposures by year of diagnosis. Mesothelioma cases in Western Australia, 1970 2004 (Number). 51 Figure 5.15 Main industry for all asbestos exposures by year of diagnosis. Mesothelioma cases in New South Wales, 1970 2004 (Per cent). 51 Asbestos exposure patterns and mesothelioma...june 2008 vii
BACKGROUND OF THE PROJECT TEAM This report was prepared by Dr Tim Driscoll (MBBS BSc(Med) MOHS PhD FAFOM FAFPHM) and Dr Jim Leigh (MBBS MD PhD MA MSc Dip NAAC, BLegS, BSc(Hons), CEng FAFPHM,FAFOEM). Both Dr Driscoll and Dr Leigh are specialists in occupational medicine and public health medicine; were previous heads of the Epidemiology Unit at the National Occupational Health and Safety Commission; and are fellows of the Australasian Faculty of Occupational and Environmental Medicine and the Australasian Faculty of Public Health Medicine. Dr Driscoll is an independent consultant in epidemiology, occupational health and public health. Dr Leigh has been undertaking research and tertiary teaching in occupational respiratory medicine for 43 years and in asbestos related disease for 21 years. ACKNOWLEDGEMENTS The authors would like to thank Ms Brooke May and Ms Julie Hill of the Office of the Australian Safety and Compensation Council for their support during the project. The authors would also like to thank the data custodians who provided access to their data for this project. Asbestos exposure patterns and mesothelioma...june 2008 viii
GLOSSARY ABA AIHW NCIS NCSCH s.d. Australian Blue Asbestos Australian Institute of Health and Welfare National Coroners Information System National Cancer Statistics Clearing House Standard deviation Asbestos exposure patterns and mesothelioma...june 2008 ix
EXECUTIVE SUMMARY The Office of the Australian Safety and Compensation Council of the Australian Government Department of Education, Employment and Workplace Relations commissioned a project to examine trends in asbestos exposure in cases of malignant mesothelioma in Australia. This report presents the findings of the project Four main data sources were available for use the Mesothelioma Register, the National Cancer Statistics Clearing House run by the Australian Institute of Health and Welfare; the New South Wales Dust Diseases Board; and the Western Australia Mesothelioma Register. Victorian data in the National Coroners Information System were also considered as a possible source of useful data. We do not believe it is feasible to use the available data sources to provide an on-going direct national estimate of trends in exposure to asbestos in persons who have been diagnosed with malignant mesothelioma. Furthermore, there do not appear to be other data sources that would potentially be available that would allow such valid direct estimates of on-going national trends to be made. However, the available data sources were considered suitable for use to produce an assessment of how exposures of malignant mesothelioma cases have changed in New South Wales and Western Australia over time in these jurisdictions. The remainder of the project considered this assessment. This analysis showed that many characteristics of the cases were similar in the two data sets, although fundamental differences in the inclusion criteria of the data sets and in the industry profiles of the two States meant that direct comparison of the industry and occupation analyses was difficult. Common findings in the two data sets were the predominance of males; an increase in the age at diagnosis and the latency in more recently diagnosed cases; first asbestos exposures commonly occurring in the 1940s, 1950s and 1960s and rarely after the 1970s; and an increasing involvement of construction-related jobs at the expense of manufacturing jobs (and of mining jobs in Western Australia). It is likely that these trends reflect those in other States and Territories in Australia. Reliable national monitoring of changes in exposure patterns and mesothelioma incidence seems an important activity for Australia, given the high per capita use of asbestos in the past and the increasing number and incidence of cases of malignant mesothelioma. To enable this, a formal system for obtaining detailed information on occupational and onoccupational exposure histories is required. Some possible alternatives to achieve this are briefly discussed. Asbestos exposure patterns and mesothelioma...june 2008 x
1. INTRODUCTION 1.1 BACKGROUND The Office of the Australian Safety and Compensation Council of the Department of Education, Employment and Workplace Relations, and its predecessor the National Occupational Health and Safety Commission, have maintained The Australian Mesothelioma Register (the Register) since its inception in 1986. The Register contains voluntary notifications of mesothelioma provided by a network of medical practitioners. The Register also contains information, where available, on the past exposure to asbestos of patients diagnosed with mesothelioma. In recent years, it has become apparent that the number of new cases notified to the Register is significantly below the number of new cases notified to the State and Territory cancer registries, to which notification is mandatory. In addition, quality information on the circumstances of past exposure to asbestos is scarcely provided. As a result, the Register is no longer an adequate source of information. Incident cases of malignant mesothelioma are notified to cancer registries and thence to the Australian Institute of Health and Welfare (AIHW) in the National cancer Statistics Clearing House (NCSCH). The AIHW can therefore provide on-going information on the number and rate of cases of malignant mesothelioma in Australia. However, the AIHW data collection does not contain any information that provides an insight into the asbestos exposure of these people diagnosed with malignant mesothelioma. There are two other data collections that do provide some information on asbestos exposure of people with malignant mesothelioma the New South Wales Dust Diseases Board and the Western Australia Mesothelioma Register. Some limited information is also available from the National Coroners Information System (NCIS) on some Victorian mesothelioma cases. The intention of the overall project was to explore the possibility of combining the information from these data sources in some way to provide an on-going direct national estimate of trends in the asbestos exposure experience of persons diagnosed with malignant mesothelioma. Alternatively, if such national extrapolation is not feasible, the New South Wales and Western Australia data were to be used to provide information on how asbestos exposures of cases have changed over time in these jurisdictions. The project was commissioned by the Office of the Australian Safety and Compensation Council to examine these issues. This report covers both aspects of the project. Asbestos exposure patterns and mesothelioma...june 2008 1
1.2 PROJECT AIMS This report aims to provide: - a consideration of the feasibility of providing an on-going direct national estimate of the asbestos exposure patterns of persons in Australia diagnosed with malignant mesothelioma; and - an analysis of data on cases of malignant mesothelioma from the Western Australian Mesothelioma Register and the New South Wales Dust Diseases Board data set. 1.3 OUTLINE OF THE STRUCTURE OF THE REPORT This report has seven chapters. The Introduction provides background regarding the project. The assessment of the data sources is provided in Chapter 2. Chapter 3 provides the assessment of the feasibility of using the data sources as required to produce an on-going direct national estimate. Chapter 4 presents the results of the analysis of Western Australian data. Chapter 5 presents the results of the analysis of New South Wales data. Chapter 6 presents an overview and a discussion of future approaches to monitoring malignant mesothelioma in Australia. Chapter 7 presents a brief summary of the report. Asbestos exposure patterns and mesothelioma...june 2008 2
2. REVIEW OF AVAILABLE DATA 2.1 INTRODUCTION Four main data sources were available for use in this project the Mesothelioma Register, the National Cancer Statistics Clearing House run by the Australian Institute of Health and Welfare; the New South Wales Dust Diseases Board; and the Western Australia Mesothelioma Register. Victorian cases in the National Coroners Information System were also thought to possibly provide some useful information and were also analysed. The main strengths and weaknesses of the data sources are considered here. 2.2 THE AUSTRALIAN MESOTHELIOMA REGISTER The Australian Mesothelioma Register began operation in 1986. The data collected by the Register was provided primarily by pathologists, treating doctors, hospital records departments and other disease registries. Cross-checking of data occurred with State and Territory cancer registries up to 1998, and from approximately this time notifications are believed to have become increasingly incomplete because of concerns by the data holders about restrictions placed upon them by privacy legislation. The Australian Mesothelioma Register included all cases from the Dust Diseases Board and the Western Australia Mesothelioma Register. Information on exposure came from a brief questionnaire completed by the notifier, often after talking to the patient or to a relative of the patient. When fully operational, missing information was followed up until all potential avenues of information were exhausted. Once the impact of changes in privacy legislation occurred, the capacity to follow up information became increasingly limited, to the stage where follow-up was essentially not possible. Information provided in the Register includes record number, surname, first names, sex, address, state, postcode, date of birth, month and year of diagnosis, age at diagnosis, primary site of the tumour, date of death, cause of death, place of death, up to three occupations (text and coded information), up to three industries (text and coded information), whether there had been exposure to asbestos and, if so, how long such exposure had occurred and whether it was related to work. The data are reasonably complete up to 1998, but thereafter the completeness, like the coverage, appears to fall. Asbestos exposure patterns and mesothelioma...june 2008 3
2.3 THE NATIONAL CANCER STATISTICS CLEARING HOUSE The National Cancer Statistics Clearing House provides data on all incident cases of malignant mesothelioma in Australia, and all deaths from malignant mesothelioma in Australia. Data are available from 1982 to 2004 inclusive and will be available on an ongoing basis. Information is available separately by gender and State or Territory of residence at the time of the diagnosis in individual reports produced by the State cancer registries. No information is available on the circumstances of exposure or the occupation and/or industry of the affected persons. No information was provided for this project on the age at diagnosis of the affected persons, although this may be available through a specific request from the AIHW. Detailed information is not freely available publicly but may be provided upon request if appropriate. The comprehensive information used in this report was confidential and specifically provided for use in this project The NCSCH should contain all cases of malignant mesothelioma diagnosed in any one year in Australia, regardless of whether exposure was deemed to be related to occupation. However, there is no way of determining whether any relevant exposure did or did not occur in relation to employment. 2.4 THE NEW SOUTH WALES DUST DISEASE BOARD DATA The New South Wales Dust Diseases Board collects data on successful claims for compensation by persons who have developed occupational lung disease as a result of exposure to some form of mineral dust. It excludes Commonwealth employees and only covers occupational exposures that occurred in New South Wales. This includes cases of malignant mesothelioma. Only persons who are believed to have been exposed to the mineral dust through the course of their own employment are included in the Dust Diseases Board Data. In terms of malignant mesothelioma, the data set provides information on the diagnosis (that is, the site of the mesothelioma); the sex and date of birth of the affected person; the date of diagnosis, year of diagnosis and the age of the person at diagnosis; the occupation and industry of the person for all jobs in which asbestos exposure was deemed to have occurred, and the year the person was first exposed in each of these jobs. The available data file comprised all cases of malignant mesothelioma diagnosed between 1962 and 2004 inclusive and for which a successful claim was made. The quality of the data appeared good, with few missing values. The occupation and industry data were not coded, but the descriptions of each category allowed them to be Asbestos exposure patterns and mesothelioma...june 2008 4
coded to at least the two digit level in the Australian New Zealand Standard Classification of Occupations (ANZSCO) and to the fourth digit of the Australian and New Zealand Standard Industrial Classification (ANZSIC). This coding was undertaken by the authors for this project. There were 1,986 cases, with more than one occupation involving asbestos exposure recorded for many of these. 2.5 THE WESTERN AUSTRALIAN MESOTHELIOMA REGISTER The Western Australia Mesothelioma Register collects information on all cases of mesothelioma diagnosed in persons living in Western Australia. There is no requirement that the exposure be connected to the affected person s occupation. The data set provides information on the sex and age at diagnosis of the affected person (the age in the supplied data was recorded in five-year age groups); a very brief description of the circumstances of the asbestos exposure apparently responsible for the development of the malignant mesothelioma; and the year of first exposure to asbestos. There are also codes that identify particular exposure circumstances, such as exposure at Wittenoom. The available data file comprised all 1,261 cases of malignant mesothelioma reported to the Western Australia Mesothelioma Register between 1960 and 2004 inclusive. The quality of the data appears good, with few missing values. There are no separate occupation and industry codes, but the brief descriptions embody one or both of these, and sometimes include a specific employer (e.g. Westrail) or a specific place (e.g. Wittenoom). There are also categories in the brief descriptions for persons known not to have been exposed to asbestos and persons whose exposure history is not known. The coded field included in the data provides exactly the same information as that provided by the brief text descriptions, as there is a one-to-one correspondence between different codes and different descriptions. The occupation and industry data are not coded. The available information would allow some of the persons to be coded to either occupation and/or industry, but the information is much less comprehensive than that provided by the New South Wales Dust Diseases Board data. (Note that very detailed exposure information was collected for many of the cases until fairly recently, but this information was not available for the current analysis). A detailed analysis of the Western Australia Mesothelioma Register data on cases up to the end of 2003 was recently published 1. 1 Mesothelioma in Western Australia, 1960 to 2003: Data from the W.A. Mesothelioma Register. In: Department of Health. Cancer incidence in Western Australia: Incidence and mortality 2003 and Mesothelioma 1960-2003. Statistical Series number 74. Department of Health: Perth, 2005. Asbestos exposure patterns and mesothelioma...june 2008 5
2.6 THE NATIONAL CORONERS INFORMATION SYSTEM Coroners investigate certain deaths in Australia. Much of the main information collected by coroners on persons who have died since the middle of 2001 is available via the National Coroners Information System. The NCIS is a national system of information and supporting infrastructure designed to provide prompt access to national coronial data to support the work of Coroners and others interested in the prevention of injury and disease. Once a person has died of malignant mesothelioma, their case could be reported to, and recorded in, the NCIS because if work-related exposure to asbestos, whether directly or indirectly, was believed to have contributed to the death, this may fall under the terms of the coroners ambit of investigating certain deaths due to external factors. When coroners do investigate a case of any sort, they have the ability to gather very detailed information, and this commonly occurs. Therefore, detailed information on the exposure circumstances would be likely to be available for those cases of malignant mesothelioma that were investigated by a coroner. However, coroners systems across Australia do not, as a rule, view such deaths as appropriate for consideration by the coroner. There have been some exceptions to this by specific coroners in specific jurisdictions, but this has been the exception rather than the rule. Therefore, the number of cases of malignant mesothelioma reported to coroners, investigated by coroners and therefore recorded in the NCIS is likely to be a gross underestimate of the true number of such cases, and the extent of under-reporting is likely to change over time in an unpredictable manner. In addition, the cases that are reported are likely to be a biased sample of all cases of malignant mesothelioma cases, so the exposure circumstances could not be held to be representative of the total even in a qualitative sense. Notwithstanding these concerns, approaches to this problem provide an insight as to whether the coronial system could, in certain circumstances, provide useful information to monitor trends in asbestos exposure. From 1 st January 2004, it has been compulsory in Victoria to report to the coroner all deaths due to malignant mesothelioma. This is possible because The Victorian Coroners Act 1985 (Section 3) requires deaths occurring directly or indirectly from accident or injury or [that] appears to have been unnatural to be reported to the Coroner. In the case of asbestos the term accident or injury relates to the initial exposure to the fibres which are lodged in the lungs and eventually over a considerable time leads to the fatal disease. Unnatural relates to the man-made Asbestos exposure patterns and mesothelioma...june 2008 6
nature of the product creating the hazard 2. Once a death is reported to a coroner, the coroner can then investigate these deaths as deemed appropriate and bring to bear all the resources and powers that can be applied to other coronial cases. This project considered aspects of the completeness of such reporting. Methods Using the web interface, the NCIS web site was searched for all cases of mesothelioma that had Victorian case numbers. This was essentially the same as identifying all Victorian deaths from mesothelioma, with the proviso that it included a few deaths of Victorian residents who died outside of Victoria whilst temporarily interstate. This search was done twice once returning coded variables and once returning the text documents relevant to the case (the post mortem, police report and Coroner s Finding). This information was used in several ways. The number of cases in each year was compared to the number of cases expected on the basis of the AIHW deaths data, which provides the accepted accurate data on the number deaths from various causes in Australia. The AIHW data are based on registered deaths. In addition, the text documents for all 2004 cases were inspected individually for evidence that exposure to asbestos was mentioned and, if so, to what extent a comprehensive exposure history was provided in the records. Results Coverage For the two years for which data were available from both the NCIS and the AIHW, the number of NCIS case files with malignant mesothelioma recorded somewhere in the cause of death was about 87% of the corresponding number of deaths in the AIHW. The percentages were less in 2004 and higher (in fact, over 100%) in 2005. The overall under-reporting suggests that not all cases were reported to the coroner, and the improvement in coverage between the 2004 and 2005 is probably primarily due to better reporting in 2005 than 2004 (as reporting authorities and coroners would have been more used to the change that occurred at the beginning of 2004). The coverage levels above 100% in 2005 probably reflect several factors. One factor is variation in the place of death, as the AIHW State or Territory of death probably reflects the jurisdiction in which the death occurred, rather than the usual jurisdiction of residence, whereas the NCIS jurisdiction may include persons who usually live in the jurisdiction but who died elsewhere. This was certainly the case with at least a few deaths included in the Victorian data. A second factor, which may explain the overreporting in 2005, is delays in reporting cases to the coroner, so that some deaths that actually occurred in 2004 were reported in 2005, although an analysis of a sample of 2 From a Finding by Victorian State Coroner (Graeme Johnstone) in 2004 in the investigation of case 2286/04. Asbestos exposure patterns and mesothelioma...june 2008 7
2005 cases reported early in 2005 did not identify any 2004 deaths. Finally, this analysis included all people with malignant mesothelioma, regardless of what their final cause of death was recorded as. There were some cases where the person had malignant mesothelioma but died of another cause (e.g. of a head injury following a fall). These persons may not have been included in the list of malignant mesothelioma deaths provided by the AIHW (Table 2.1). Table 2.1 Deaths due to malignant mesothelioma Victoria, 2004 and 2005 AIHW versus NCIS. Year AIHW male AIHW female AIHW total 2004 107 20 127 2005 92 18 110 Total 199 38 237 VIC male VIC female VIC total 2004 74 11 85 2005 100 22 122 Total 174 33 207 Comparison 1 male (%) Comparison female 1 (%) Comparison total 1 (%) 2004 69.2 55.0 66.9 2005 108.7 122.2 110.9 Total 87.4 86.8 87.3 1: NCIS deaths as a percentage of the relevant recorded AIHW deaths. Information on asbestos exposures Information was potentially available from three documents on the NCIS the autopsy report, the police report and the Coroner s Finding. For the 2004 cases, the autopsy report was missing for 13% of cases, the police report was missing for 38% of cases and the Finding was missing for 4% of cases. Useful information on asbestos exposure history was available from the autopsy for 25% of cases, from the police report for 37% of cases and from the Finding in 72% of cases. A minor mention of asbestos, or of the presence of asbestos-related changes in the lung, was made in 12%, 5% and 2% of the documents, respectively (Table 2.2). The quality of the information on asbestos exposure that was considered useful varied considerably between documents. Commonly there was one line of information (e.g. It is believed the deceased was exposed to asbestos whilst working in a factory (from steam pipes) about forty years ago. ). This was the case for most of the autopsy reports and police reports that mentioned the asbestos exposure history, with a minority providing a little more detail. The Finding commonly provided more detailed information, with typically several sentences providing a reasonable summary of the exposure history. Asbestos exposure patterns and mesothelioma...june 2008 8
In three of the 85 cases, a very detailed Finding was made, with a complete occupational and other exposure history and consideration of the broader problem of asbestos exposure highlighted by the individual case. The exposure history appears to have nearly always been provided by a relative of the deceased, but there were some instances in which an occupational hygienist provided a complete history. In addition, reference was sometimes made to court proceedings that had been settled or were underway, and some of the information in the Finding may have come from documents associated with these legal actions. Table 2.2 Mention of asbestos exposure circumstances in NCIS documents for deaths due to malignant mesothelioma Victoria, 2004. Autopsy report (%) Police report (%) Coroner s Finding (%) Male (n = 74) Missing 1 13.5 39.2 1.4 Good information 2 24.3 35.1 71.6 Mention 3 12.2 5.4 2.7 No mention 4 50.0 20.3 24.3 Total 100.0 100.0 100.0 Female (n = 11) Missing 9 27 18 Good information 27 46 72 Mention 9 0 0 No mention 55 27 9 Total 100 100 100 Total (n = 85) Missing 12.9 37.6 3.5 Good information 24.7 36.5 71.8 Mention 11.8 4.7 2.4 No mention 50.6 21.2 22.4 Total 100.0 100.0 100.0 1: The report was not available on the NCIS. 1: The report contained some specific information on asbestos exposure circumstances. 3: The report contained passing reference to asbestos. 1: The report did not mention asbestos. Asbestos exposure patterns and mesothelioma...june 2008 9