Document Gm8ZDo3vZ7knM3zGg1Eze7VnN

ga5ag5CS^^7B^ais^gsg^s S4 . - BRITISH JOURNAL OF INDUSTRIAL MEDICINE Table 4 the increase in mortality attributed to lung'canoer CAUSES OF DEATH AMONG MALE ASBESTOS WORKERS COMPARED WITH MORTALITY EXPERIENCE OF ALL MEN IN ENGLAND AND WALES over the past 30 years is certainly due to improvements in diagnosis and in therapy (.Doll, 1933). Even, however, if it were postulated that the whole Cftust of Doth No. of Deaths j Tru of SicnJffCaiYOc Expected of Difference on ] between Ho. i England Observed Observed wtowd$ and Expected Rate*. (VnLxbTP) of the recorded increase between 1931 and 1951 was spurious and that the real mortality from the disease throughout was that ascribed to It in 1951, the expected number or deaths is increased to only H and the observed excess is stilt grossly significant! Lim; oncer*: vilh oentioa of nbotoiit.. without dealtoo of osbcafiotU Other respiratory <Hm (todud- :inf pulrnocuuy tubcrculosty sod card'tovascuhx dbeaic* with mention of asbestos ... vitboul znetxfon of ubotowt it 0 14 } <0000001 0-8 } <0001 7-6 For the actual number or lung cancer cases to be so little in excess of the expected as to be reasonably attributable to chance, it would be necessary for the expected cases to be 6-2, that is 3*6 times the number estimated on 1951 rates. In other words, it would be necessary to postulate that in 1951 (and throughout Ncoplutos other than fuss cancer All other djKWf.. ,, 4 2-3 }Ol 4-1 the previous 20 years) there was 5.6 times as much cancer of the lung as was recognized in 1931, AUouset .. ,, 1S4 <0000001 which would mean that the condition would have * lodudloi oee cam with puIowAary-tvbe/cylcnu. tlndudm# i*o out (benign stricture of oesophagus sad scpt>cacnua) in which astotosis was oresent hut was not thought to have been a oontribeiofy cause ofdeath. to have been present and capable of detection in over 20% of all men at death. Moreover, even if this were so, it would still not account for the fact that all the- cases of lung cancer were found in an increased {rabrfeEty JrpTM lun cancer, other association with asbestosis., , frespiratoryIdiseasesrand cardiovascular diseases, in It is, therefore/cOncludedThat the fourth explan association irith'asbestosis, but that their mortality ation is the most reasonable one and that the dsSBtos from other discasesWas dose to that expected. workers who had worked for 20 or more yeanmthe Four .explanations-of tbs findings are possible : ".scheduled areas " suffered a notably, highermsk (1) that all the men who had died of lungcancer were from lung cancer-than the rest or the population- recorded because of interest in the condition, but To test if the risk' lias altered since the 1931 that some of the records of other men dying of other regulations were introduced, it is not only necessary diseases or still alive were omitted, with consequent to make allowance for duration of employment underestimation of the expected number of deaths; before the end of 1932, but also to allow for the men's (2) that lung cancer was incorrectly and excessively ages and for the total durations or their employment diagnosed among the asbestos workers; P) that in the " scheduled areas ", since the men employed lung cancer was insufficiently diagnosed among the in the earlier periods can also have been employed general population of England and Wales; or (4) longer and lived to be older. On the other hand, that the asbestos workers studied suffered an excess there is no need to consider the changing incidence mortality from lung cancer. of lung cancer in the total population of England and Jt certainly cannot be claimed that the records or Wales since the nori-industrial risk has been shown the Personnel Office were necessarily complete, but to be small in comparison with the industrial one. they were believed to be complete and no deficiency The data required forcomparingthe risks among men on this score would account for.the .total excess of employed Tor under 10 years, for 10 to 14 years, and deaths unless it were so gross that more thari half the for IS years and over in the prc-1933 conditions arc defined population had been omitted. Moreover, the shown in Table 5. The ages shown' are the ages at number or deaths due to conditions unrelated to death of the men who have died and the ages in mid- asbestosis was dose to the estimated number and this 1953 for the men who arc still alive. The expected is unlikely to have happened unless the population numbers or men in each pre-1933 employment group had been estimated approximately correctly and the found to have asbestosis or asbestosis and lung deaths from all causes fully reported. cancer are estimated by multiplying the numbers in All the 11. deaths attributed to lung cancer were - each age, total employment, and pre-1933 employ- confirmed by necropsy-andbustblogical examination ment subgroup by the proportions of men with so that the excess number cannot be attributed to asbestosis or with asbestosis and lung cancer in the incorrect diagnosis among the group of asbestos same age and total employment group for all lengths workers. Some of the excess may welt be due to an of pre-1933 employment combined. For example, underestimation of the expected deaths since part of three out of the nine men aged 50 to 54 years who had