Document aBqnKjpw2rX6pLeRNnjrbEXDe

Ann. occup. Hyg., Vol. 46, Supplement 1, pp. 160-165, 2002 2002 British Occupational Hygiene Society Published by Oxford University Press DOI: 10.1093/annhyg/mef669 Malignant Mesothelioma in Australia, 1945-2000 JAMES LEIGH1*, PATRICIA DAVIDSON1, LEIGH HENDRIE2 and DALE BERRY2 1Centre for Occupational and Environmental Health, Department of Public Health and Community Medicine, University of Sydney, Sydney, NSW; 2National Occupational Health and Safety Commission, Sydney, NSW, Australia Australia has maintained a national malignant mesothelioma register since 1980. The register includes all cases in Australia. Currently 450-600 cases are notified annually in a population of 20 million. Australia has had 6329 cases of mesothelioma in the period 1 January 1945 31 December 2000. A further 680 cases have been notified in the period 1 January 2001-31 December 2001. Annual incidence rates for Australia per million population >20 yr (1998) were male, 59.8; female, 10.9; total, 35.4. Incidence rates have been continually increasing in males and females and are the highest reported national rates in the world. While Western Australia has the highest rate (1998, 52.8), most cases arise from the two most populous eastern states, New South Wales and Victoria. In 88% (male 90%, female 61%) of cases a history of asbestos exposure was obtained. Exposures occurred in a wide variety of occupational and environ mental circumstances. In 81 % of cases with no history of exposure, TEM lung asbestos fibre counts >200000 fibres >2 pm length/g dry lung were obtained, suggesting unrecognized exposure. Australia's high incidence of mesothelioma is related to high past asbestos use, of all fibre types, in a wide variety of occupational and environmental settings. The number of cases in total is expected to be about 18000 by 2020, with about 11000 yet to appear. Keywords: malignant mesothelioma; incidence; Australia; asbestos exposure; future predictions INTRODUCTION Asbestos was mined in Australia for over one hundred years and Australia was the world's highest user per capita of asbestos in the 1950s. Given the ecological relationship between per capita asbestos consumption and mesothelioma incidence (Takahashi et al., 1999), it is no surprise that in the last 20 yr of the 20th century Australia has had the world's highest reported incidence of malignant mesothelioma. Australia has one of the world's most complete national surveillance systems for mesothelioma and this has been in operation since 1980. It is the purpose of this paper to describe the history of asbestos use and the incidence of mesothelioma in Australia as a whole, rather than concentrating on the well-known Wittenoom crocidolite mining operation and town ship in Western Australia (Musk et al., 1992). The *Author to whom correspondence should be addressed. Centre for Occupational and Environmental Health, Department of Thoracic Medicine, Concord Hospital 2139, NSW, Australia. Tel: 61-2-9767-7338; fax: 61-2-9767-7605; e-mail: jleigh@bigpond.com paper updates and enhances previous reports (Leigh et al., 1991, 1997, 1998; Leigh, 1994). MATERIALS AND METHODS Australian Mesothelioma Surveillance Program (Ferguson et al., 1987) The Program began on 1 January 1980 after preliminary work from 1977. Formal voluntary noti fication of cases was actively sought from a network of respiratory physicians, pathologists, general and thoracic surgeons, medical superintendants, medical records administrators, state and territory departments of occupational health, cancer registries, compensa tion authorities or any other source. Notifications from other than the diagnosing physician were confirmed with him/her. After gaining the appropriate consents a full occupational and environmental history was obtained for each case, either from the patient or next of kin. The history taking was non-directive but included specific questions on asbestos exposure at the end. These histories were coded by two occupa tional hygienists, who naturally could not be blinded to case status. They also discussed cases together and 160 162 J. Leigh et al. Fig. 3. Time trend of annual incidence rate (per million population >20 yr) of mesothelioma in Australia by sex, 1982-1998. utes only 15% of the total cases. Wittenoom contrib utes only 5% of the Australian cases yet is certainly the most publicized and best known internationally. Most of the cases come from the two most populous and industrialized states, New South Wales and Victoria. In 93.2% of all Program cases the mesothelioma was pleural in site, 6.5% peritoneal and only 0.3% of cases in other sites. Among men 94.3% were pleural, 5.3% peritoneal; among women 86.3% were pleural, 13.7% peritoneal. These proportions have been generally maintained in Register cases although the female peritoneal proportion has dropped to 10.4%. The most common occupational exposures were repair and maintenance of asbestos materials (18%), shipbuilding (11%), asbestos cement production (7%), asbestos cement use (7%), railways (6%), Wittenoom crocidolite mining/milling (6%), insula tion manufacture/installation (4%), wharf labouring (3%), power stations (3%), boilermaking (2%), paraoccupational hobby and environmental (15%). When the earlier cases classed as `no history of exposure' were reviewed it was found that 57 of the 203 so classified actually had a history of some exposure recorded. Thus only 19% had no known history. Moreover, of this `no known history' group, 81% had 164 J. Leigh et al. et al., 1991 ). Three percent of cases had exposures of less than 3 months. According to history assessment of the first exposure of the first 530 cases by the two hygienists, most cases (55%) had mixed amphibolechrysotile exposure, 13% amphibole only, 7% amphibole, plus possible chrysotile, 6% chrysotile, with possible amphibole, and 4% chrysotile only, with 15% unknown fibre type (Grimwood, 1988). Mean latency from first exposure to presumptive diagnosis was 37.4 yr (Ferguson et al., 1987). The range of latencies was 4-75 yr. In the cases reported since 1 January 1986, when less detail of history of exposure was sought, 89.9% of males responding to the questionnaire and 61.2% of females gave a history of asbestos exposure (overall 86.4%) (non-response 22% males, 30% females). The pattern of exposure history is changing, and more product, domestic, environmental and paraoccupational exposure is apparent, compared to the older traditional industries. Exposure occurred in a wide range of occupations and industries and nonoccupational settings. Some common exposure histories were: repair and maintenance of asbestos materials (13%), shipbuilding (3%), asbestos cement production (4%), railways (3%), powerstations (3%), boilermaking (3%), Wittenoom (5%), wharf labour (2%), para-occupational, hobby, environmental (4%), carpenter (4%), builder (6%), navy (3%), plumber (2%), brake linings (2%), multiple (12%). Risk in particular occupational groups Approximate lifetime risks in occupational groups exposed 30-50 yr ago were obtained as follows: Lifetime risk (%) = (70 x number of mesothelioma cases notified 1986-2000 x 100)/(population in occupation category in Australia x 15) Table 2 shows the results for the major identifiable occupational groups. Population denominator data was estimated from census data, Australian Bureau of Statistics (ABS) data, cohort data for Wittenoom, defence data for the navy and union data for waterside workers. As the range of latencies was 4-75 yr, the relevant occupa tional group population sizes were estimated as the mean of the 1933 and 1997 value, except for Wittenoom, navy and waterside workers, where industry, defence and union data was used. CONCLUSION The high and increasing incidence of meso thelioma in Australia is due to high asbestos use in the past, combined with poor hygiene practice, rela tively high amphibole use in asbestos cement products, slow recognition of chrysotile mesotheliomagenicity and excessive focus on Wittenoom Table 2. Mesothelioma risks in occupational groups Occupation Lifetime risk of mesothelioma (%) Wittenoom mine or mill worker 16.6 Power station worker 11.8 Railway labourer 6.4 Navy/merchant navy 5.1 Wittenoom town 3.1 Carpenter/joiner 2.4 Waterside worker 2.1 Plasterer 2.0 Boilermaker/welder 1.9 Bricklayer 1.8 Plumber 1.7 Painter/decorator 1.2 Electrical fitter, mechanic, electrician 0.7 Vehicle mechanic 0.7 All Australian men 039 All Australian women 0.07 to the exclusion of other more common exposures. There was also a reluctance to recognize the causal significance of low occupational and non-occupational exposures. The expected total number of mesothelioma cases in Australia from 1945 to 2020 is estimated to be about 18 000, based on models by Berry (1991) and de Klerk et al. (1989) for Wittenoom, extrapolated to Australia as whole (assuming Wittenoom contributes 5% of cases), and direct extrapolation from the best fit to the empirical incidence curve, constrained to have a maximum value at 2010, following a 40 yr latency from the time of maximum exposure (1970) (Fig. 4). This will create a heavy clinical and compen sation load. Cases will arise from a large variety of occupations and workforces and environmental and para-occupational circumstances. Although classic cohorts related to insulation work and crocidolite mining will have the highest risks, occupations such as carpenters, builders, plumbers and electricians, because of numbers employed, will generate similar case loads. With asbestos-related lung cancer estimated to occur at a ratio of 2:1 to mesothelioma (Barroetavena et al., 1996) the expected future case load of asbestos-related cancer can be expected to be of the order of 30 000-40 000 by 2020. These predictions are consistent on a population and asbestos use adjusted basis with those made for Europe (Peto et al., 1999), Scandinavia, USA, Japan (Takahashi et al., 1999) and New Zealand (Kjellstrom and Smartt, 2000). The various Australian state and federal government preventive, clinical and compensatory authorities are now developing a national strategy for dealing with this problem. Malignant mesothelioma in Australia, 1945-2000 165 REFERENCES Barroetavena MC, Teschke K, Bates DV. (1996) Unrecognised asbestos-induced disease. Am J Ind Med; 29: 183-5. Berry G. (1991) Prediction of mesothelioma, lung cancer, and asbestosis in former Wittenoom asbestos workers. Br J Ind Med; 48: 793-802. de Klerk NH, Armstrong BK, Musk AW, Hobbs MST. (1989) Prediction of future cases of asbestos-related disease among former miners and millers of crocidolite in Western Australia. Med J Aust; 151: 616-20. Ferguson DA, Berry G, Jelihovsky T et al. (1987) The Australian Mesothelioma Surveillance Program 1979-1985. Med J Aust; 147: 166-72. Grimwood A. (1988) Mesothelioma and asbestos in Australia. MPH Treatise, University of Sydney. Hillerdal G. (1999) Mesothelioma: cases associated with nonoccupational and low dose exposures. Occup Environ Med; 56: 505-13. Kjellstrom T, Smartt P. (2000) Increased mesothelioma inci dence in New Zealand: the asbestos-cancer epidemic has started. NZ Med J; 113: 485-90. Leigh J. (1994) The Australian Mesothelioma Program 1979 1994. In Peters GA, Peters BJ, editors. The current status of the asbestos public health problem. Volume 9: Sourcebook on asbestos diseases. New Hampshire: Butterworth. pp. 1 74. Leigh J, Corvalan CF, Grimwood A, Berry G, Ferguson DA, Thompson R. (1991) The incidence of malignant mesotheli oma in Australia 1982-1988. Am J Ind Med; 20: 643-55. Leigh J, Davidson P, Hull B. (1997) Malignant mesothelioma in Australia 1945-1995. Proc Inhaled Particles VIII. Ann Occup Hyg; 41 (suppl. 1): 161-7. Leigh J, Davidson P, Hull B. (1998) Malignant mesothelioma in Australia (1945-1997). Excerpta Medica Suppl. 53. Adv Prev Occup Resp Dis; 299-302. Musk AW, Dolin PJ, Armstrong BK, Ford JM, de Klerk NH, Hobbs MST. (1989) The incidence of malignant meso thelioma in Australia 1947-1980. Med J Aust; 150: 242-6. Musk AW, Dewar J, Shilkin KB, Whitaker D. (1991) Miliary spread of malignant mesothelioma without a clinically iden tifiable pleural tumour. Aust NZ J Med; 21: 460-2. Musk AW, de Klerk NH, Eccles JL, Hobbs MST, Armstrong BK, Layman L, McNulty JC. (1992) Wittenoom, Western Australia: a modern industrial disaster. Am J Ind Med; 21: 735-47. NOHSC. (1989-2001) National Occupational Health and Safety Commission (National Institute of Occupational Health and Safety). Australian Mesothelioma Register Report. The Incidence of Mesothelioma in Australia. Annual Report Series. New South Wales Cancer Council. (2000) Cancer in New South Wales. Incidence and Mortality 1997. Peto J, Decarli A, La Vecchia C et al. (1999) The European mesothelioma epidemic. Br J Cancer; 79: 566-672. Takahashi K, Huuskonen MS, Tossavainen A, Higashi T, Okubo T, Rantanen J. (1999) Ecological relationship between mesothelioma incidence/mortality and asbestos consumption in ten Western countries and Japan. J Occup Health; 41: 8-11.