Document RjzaXoo0RzM1YmYXML6KO104X

*tm* an, 1 ixelsm Occupational and Environmental Medicine 1995;52:775-777 775 >^en in tht dary to |not all lack of - degree of create the sconsideranical inforie subjects scepticism, that those have been urveiilance es cany all le cause of at Boquist necrosis in 'oxylamine xperimennot clear, alent inorhave urine c/1, mainly is widely minerals. crust are arsenic is intent by ) arsenic rkers and use of #l glass arsenic iukaemia, na and as indred ftg ometimes :nic/l, for. alt of the c. These e considnudies to ions of a Chen S-Y. i prevalence :485-9l. mlund SO. crent study Med 197". ; analysis ol ;Vuf/ ClllkVf ,f freedom- ?. Aifteru'jv ). I beta ccH ice treated acid C>vlc jhh cnfcnd .n, 1981. MRC Environmental Epidemiology Unit, University of Southampton, Southampton Genera! Hospital, Southampton SQ16 6YD 0 Coggon H Inskip P Winter B Pannett Correspondence to: Dr David Coggon, MRC Environmental Epidemiology Cnit, University of Southampton, Southampton fierwral Hospital, Southampton SO 16 6YD. Avcrptcd 28 June 1995 Differences in occupational mortality from pleural cancer, peritoneal cancer, and asbestosis David Coggon, Hazel Inskip, Paul Winter, Brian Pannert Abstract Objective--To assess whether the increased risk of disease related to asbestos in occupations from the con struction and engineering industries applies equally to pleural cancer, peri toneal cancer, and asbestosis. Methods--Analysis was based on deaths among men aged 20-74 in England and Wales during 1979-80 and 1982-90. (n = 1656 096). Information about cause of death and the last full time occupation of decedents was derived from death certifi cates. Proportional mortality ratios (PMRs) by occupation were calculated for each of pleural cancer, peritoneal cancer, and asbestosis. Results--Altogether, 2848 deaths were attributed to cancer of the pleura, 362 to cancer of the peritoneum, and 281 to asbestosis. When occupations were ranked according to PMRs from these diseases, striking differences were found. The category of construction workers which included laggers had the highest mortality from peritoneal cancer (PMR 990, 64 deaths), but a PMR of only 160 (77 deaths) for pleural cancer. In contrast, several occupations with much higher mortality from pleural tumours had no excess of peritoneal cancer. PMRs for asbestosis related more closely to those for peritoneal than pleural cancer. Conclusions--These findings suggest that the exposure-response relations for dis eases related to asbestos are not all linear, and that risks of pleural mesothelioma may be underestimated by simple extrap olation from observations in cohorts with heavy exposure. (Occup Environ Med 1995;52:775-777) One starting point is to identify the occupa tions associated with excess mortality from diseases related to asbestos. During the 1980s, a large proportion of male deaths from mesothelioma in England and Wales were related to work in the construction and engi neering industries.' It is unclear whether the increased risk in these jobs applies to mesothe lioma of the pleura, peritoneum, or both. We have analysed data from the same period that indicate important differences in the relative frequency of pleural and peritoneal mesothe lioma by occupation, and which may have implications for control strategy. Method Our analysis was based on all deaths among men aged 20-74 in England and Wales in 1979--80 and 1982-90. Data for 1981 were unreliable because of industrial action in that year by registrars of deaths. Information about the age, underlying cause of death, and most recent full rime occupation of decedents was obtained from death certificates. Causes of death were coded to the ninth revision of the international classification of diseases (ICD9), and occupations were coded initially to the Office of Population Censuses and Surveys (OPCS) 1980 classification of occupations^ The occupational units defined in the OPCS classification were then aggregated into 194 larger job groups.' For each job group we calculated propor tional mortality ratios (PMRs) for cancer of the pleura (ICD-9 = 163), cancer of the peri toneum (ICD-9 = 158-8 and 158-9), and asbestosis (ICD-9 = 501), with five-year age specific proportions in all occupations com bined as the standard. Confidence intervals (CIs) for PMRs were based on the Poisson distribution. Keywords: asbestos; mortality; mesothelioma Occupational exposure to asbestos is a major cause of mortality from asbestosis, mesothe lioma, and bronchial carcinoma. In Britain, legal controls on exposure to asbestos were first introduced in 1933, and since then have been progressively tightened. Recent analysis indicates that mortality from mesothelioma is rising in men at most ages, and suggests that overall rates will continue to increase through to the next century.' It is important to estab lish whether this trend results from inadequate enforcement of statutory exposure limits, or whether the limits themselves are not suffi ciently stringent. Results Over the 11 year period of study 1 656 096 deaths were recorded in men with adequately described occupations, including 2848 from cancer of the pleura, 362 from cancer of the peritoneum, and 281 from asbestosis. The table lists the job groups with significantly (P < 0-05) raised PMRs for at least one of these diseases. The ranking of PMRs for cancers of the pleura and peritoneum was quite different. For example, construction workers no, where classified (nec), a group whict -- laggers, had the highest mortality ftoneal cancer (PMR 990, 64 deaths HWBUI0011427 ^ Job. tsilh significantly (P < Q-05) raised mortalityfront cancer of the pleura, cancer of the peritoneum, or asbesiosis Job group Metal plate workers Vehicle body builders Plumbers and gas Suers Upholsterers Carpenters Electricians Electrical plant operators Chemical engineers and scientists Welders Managers in construction Boiler operators Electrical engineers (so described) Production httets Plasterers Sheet metal workers Builders and handymen Professional engineers nec Construction workers nec Architects and surveyors Dockers and goods porters Chemical workers Preparatory fibre processors Smiths and forgemes Machine tool operators Occupational units* from qU causes 124-3, 126 2 129-3, 131-1 124-1, 125 101-4, 103 104-1, 105 1 120-2, 121-2 120-3, 121-4 024-2, 028-1 5867 2256 16941 2763 27425 20517 268! 2712 124-6, 128 035-1,035-2 159-9, 161-1 121-3 12467 7404 6212 7930 114*4, ||7 52566 139-3, 140-3 5198 124-2, 126-1 7961 139-5, 140-5, 140-6 22433 025, 026-1,026-2, 028-2, 17780 028-3, 028-4,028-6 139-12, 143 1,143-2, 26886 146-2 031-1, 031-2,031-3 7463 156-2,156-3,157-2, 157-3 13603 088, 089, 159-2, 160-2 15480 086-1, 087-1 862 108-3, 109-3 2770 111 4, 112 4 50854 Cancer ofpteu Deaths PMR (95% Cl) 73 709 556-892 24 649 416-968 134 450 377-533 16 366 209-594 167 362 309-421 127 349 291-415 14 301 365-506 13 274 146-468 56 247 32 240 24 240 31 227 186-320 164-340 153-357 154-323 192 208 180-240 18 207 122-327 25 186 120-274 65 166 128-212 53 162 321-212 77 160 126-200 21 160 99-245 36 156 109-216 39 144 103-198 2 139 17-501 6 133 49-289 116 132 109-158 Cancer ofperiic Deaths PMR (95% Cl) l 78 2-432 4 877 239-2246 11 283 141-506 0 0 0-688 6 102 37-221 4 83 23-212 0 0 0-643 0 0 0-597 1 33 1-186 6 349 128-759 2 171 21-616 1 58 1-325 12 103 53-179 3 265 55-773 4 235 64-602 5 98 32-229 2 46 6-168 64 990 762-1265 ! 58 1-324 7 242 97-500 5 146 47-341 0 0 0-2049 3 561 116-1639 15 136 76-224 Asbestosis Deaths PMR (95% C!) 3 292 5 ^ 1302 13 457 00 9 196 l 29 I 212 00 60-854 423-3039 243-782 0-802 90-372 1-164 5-1180 0-813 3 142 29-415 1 77 2-429 4 366 100-937 1 74 2-410 17 189 110-303 0 0 0-431 4 300 82-768 0 0 0-98 0 0 0-120 71 1592 1243-2009 0 0 0-297 4 no 46-435 5 169 61-441 2 1316 159-4753 0 0 0-765 n 126 63-226 *As defined in die OFCS 1980 classification of occupations, nec = not elsewhere classified. \~ PAIR of only 160 (77 deaths) for pleural can cer. In contrast, several of the occupations with the highest mortality from cancer of the pleura--metal plate workers (PMR 709, 73 deaths), upholsterers (PMR 366, 16 deaths), carpenters (PMR 362, 167 deaths) and electri cians (PAIR 349, 127 deaths)--had no excess of peritoneal cancer. Mortality from asbestosis was more closely related to that from peritoneal than pleural cancer, with the highest PMR again in con struction workers nec (PAIR 1592, 71 deaths). The Spearman rank correlation coefficient across the 24 job groups in the table was 0-43 for asbestosis with cancer of the peritoneum and 0-15 for asbestosis with cancer of the pleura. Discussion In this analysis we restricted attention to the three causes of death that are related most specifically to asbestos. Asbestos also causes bronchial carcinoma, but the effect is less dis cernible in analyses of occupational mortality because the relative risk is smaller and because associations are confounded by differences in smoking and exposure to other lung carcino gens in the workplace. The analysis was limited by inaccuracies that are known to occur in information obtained from death certificates. Not all deaths ascribed to cancers of the pleura or peritoneum are mesotheliomas, and some mesothelioma deaths are classified as cancers of other or unspecified sites.* Also, some deaths may be incorrecdy attributed to asbestosis on the basis of pleural thickening or plaques, when no fibrosis is present. Moreover, data were only available on the most recent full time job of decedents, and some subjects will have been exposed to asbestos in earlier employment about which we had no information. In general, however. the effect of such errors should be to attenuate occupational associations, and they would not be expected to have a differential effect on the ranking of occupations by mortality from dif ferent diseases related to asbestos. The use of periodic medical examinations or an unusually high rate of necropsies in certain occupations might boost the detection of peritonea) more than pleural tumours, but it would not explain such large discrepancies in the relative fre quencies of these diseases as were found. Nor would it account for the high frequency of deaths from asbestosis in some occupations with relatively low mortality from pleural cancer. Another limitation was the use of propor tional mortality rather than true death rates. Although PMRs may have been somewhat depressed or inflated by differences in the overall death rates of job groups, the effect should be similar for each of the three diseases examined, and again would not explain the contrasting ranking of jobs by PMR. The occupations with significantly raised PMRs in our analysis were largely the same as those found previously to have high mortality from mesothelioma overall.1 All entail poten tial exposure to asbestos although in some cases the exposure is related to work in specific industries rather than a general feature of the occupation. For example, the excess mortality among welders occurred mainly in centres of shipbuilding.5 Many of the high risk occupa tions are in the construction industry where exposure has occurred from the use of asbestos in lagging and other building materi als. The high PAIR for cancer of the pleura in carpenters compared with many other build ing trades may be related to work with asbestos board. Notable for an absence of sig nificant risk are motor mechanics, (PMR 46, 12 deaths from pleural cancer; PAIR 88, three deaths from peritoneal cancer; PAIR 80, two deaths from asbestosis) about whom concerns HWBUI0011428 ** ftztr.itn 50-854 !3-3039 13-782 0-802 >0-372 1-164 5-1180 0-813 19-415 2-429 >0-937 2-410 10-303 0-431 12-768 0-98 0-120 13-2009 0-297 16-435 >1-441 59-4753 0-765 >3-226 tenuate uld not : on the om dif: use of msually ive fretd. Nor sncy of .pations pleural proporh rates, tiewhat in the i effect h'seases ain the raised :ame as ortality potent some specific ` of the ortality sires of ccupa- where JSC of materieura in Differences in occupational mortalityfrom pleural cancer, peritoneal cancer, and asbestoses 777 have been raised because of the presence of pleural cancer is lower and diluted to a level asbestos in brake linings. It seems that this below that in occupations such as carpenters exposure has no important effect on mortality where a larger proportion of men are exposed, from mesothelioma or asbestosis, perhaps but at a lower level! because the asbestos fibres are modified by This hypothesis is consistent with findings heat. on the ratio of pleural to peritoneal mesothe The difference in the ranking of occupa liomas in cohort studies of asbestos workers, tions by mortality from pleural and peritoneal where peritoneal tumours have tended to be cancer and asbestosis is striking and cannot relatively more common in cohorts with longer realistically be ascribed to chance. Nor is it and heavier exposures,67 although with occa likely to be explained simply by differences in sional exceptions.8 It also accords with the 1 the types of asbestos to which occupations are finding of higher fibre contents in the lungs of exposed. Crocidolite and amosite are more patients dying from peritoneal compared with 1 potent causes of mesothelioma than pleural cancer.* It is an indication for caution chrysorile,5 and ail of the occupations with when extrapolating risk estimates for mesothe I ' high PMRs from peritoneal cancer could have lioma at low exposures to crocidolite and involved exposure to crocidolite. But welders, amosite from observations in cohorts with | who had a higher PMR than construction heavy exposure. In particular, the risks of workers nec from pleural cancer, are also likely pleural mesothelioma may be underestimated ; to have had exposure to crocidolite (especially if a linear exposure-response is assumed. This those employed in shipbuilding), and yet had a should be taken into account when control deficit of peritoneal cancers. limits are reviewed. A more plausible explanation is that the exposure-response relations for mesothelioma and asbestosis are non-linear, with the risk of pleural mesothelioma increasing relatively We ihartfc the Office of Population Censuses and Surveys for providing us wish the mortality data, and Dr Corrado Magnani for his helpful comments on the findings. The analysis was sup ported by a grant from the Health and Safety Executive. more steeply at low exposures but less steeply at high exposures. Where an occupation entails low exposure to asbestos, excess pleural cancer occurs but there is little effect on peritoneal cancer or asbestosis. With high exposures, the risk of pleural cancer is increased further, but that of peritoneal cancer and asbestosis goes up much more and becomes dominant. Also, the effect on occupational mortality is diluted according to the proportion of men in the job group who are exposed. For example, con struction workers nec include not only laggers with very high exposure to asbestos, but also other occupations such as floor layers with minimal exposure. As a consequence, the PMRs of the group are reduced for diseases related to asbestos. In the case of peritoneal cancer and asbestosis, the risk in laggets is so high that the PMR of the job group as a whole remains highest in the ranking. The PMR for 1 Peio J, Hodgson )T, Matthews FE Jones JR. Continuing increase in mesothelioma mortality in Britain. Lancet 1995;345:535-9. 2 Office of Population Censuses and Surveys. Classification of occupations 1980. London: HMSO, 1980. 3 Office of Population Censuses and Surveys/Health and Safety Executive. Occupational Health Decennial Supplement. London: HMSO, 1995. 4 Newhouse ML, Berry G Wagner JC. Mortality of factory workers in East London. 1933-80. Br J 7d Med 1985;42:4-11. 5 Acheson ED, Gardner MJ. Asbestos: the control limit for asbestos. London: HMSO, 1983. 6 SclikofflJ, Hammond EC, ChurgJ. Mortality experiences of asbestos insulation workers 1943-68. In: Shapiro HA, ed. Pnewnocenwm: proceedings of the international confer ence, Johannesburg. Capetown: OUP, 1969:180-6. 7 Browse K, Smkher Wj. Asbestos^related mesothelioma: factors discriminating between pleural and peritoneal sites. BrJ Ind Med 1983;40:145-52. 8 Armstrong BK Musk AW, Baker JE, Hunt JM, Newali CC Henzell HR, a al. Epidemiology of malignant mesothelioma in Western Australia. Med J Amt 1984; 141:86-8. 9 Wagner JC, Newhousc ML, Corrin B, Rossiter CER, Griffiths DM. Correlation between fibre content of the lung and disease in East London asbestos factory work ersrBrJIndMed 1988;45:305-8. i iR 46, three 0, two ncems HWBUI0011429