Document 6RJbKd2Y3ddo4G9vvn46eo9aE

Section III. Human Exposure to An sextos: Industki.u. Poeri..*-'-"''-- ASBESTOSIS.IN GREAT BRITAIN J.'C. McVittie Ministry of Pensions and National Insurance, London, England Our knowledge of asbestosis dates from a post-mortem examination car ried out at the Charing: Cross Hospital, London, 64 years ago. The findings of that post-mortem examination were given by Montague Murray1 in evi dence before a Departmental Committee on Compensation for Industrial Diseases is 1906, He gave a good description of the morbid anatomy of pulmonary asbestosis and he produced photographs taken from specimens showing spicules of asbestos in the lungs of his young patient who died after 10 years exposure to cardroom dust. Eighteen years were to elapse before another post-mortem examination again directed attention to the possibility that silicates may cause extensive pulmonary fibrosis. In the interval interest was concentrated on what was regarded as the more im portant and widespread risk associated with dusts containing free silica. The second case was reported by Cooke* in 1924. the first to appear in Eng lish medical literature. His case is frequently associated with the dis covery of "curious bodies" but what Cooke demonstrated in the lungs of a young tuberculous female textile worker were actual particles of asbestos fibers and dust, and he always insisted that proof of the diagnosis did no? include the presence of "curious bodies." Then suddenly, between 1927 and 1931. a whole new literature relating to asbestos appeared in Britain. The clinical picture of pulmonary asbes tosis was described by Oliver.2 and the clinical and X-ray findings by Seiler,4 Burton Wood.1 and Ellman.6 Stuart McDonald* described the his tology of pulmonary asbestosis, and referred to certain highly character istic yellowish brown bodies abundant in all sections. He advanced thr hypothesis that the bodies were portions of asbestos fibers in the process of alteration. Stewart' described how the characteristic bodies could !** detected immediately by making a lung "squeeze." Unfortunately he drscribed them as "asbestosis" bodies. Later Roodhouse Gloye:' suggest***! that "asbestos" bodies would be a better name. In the new literature thr report by Merewether and Price** in 1930 was outstanding. The report gave their conclusions and recommendations following an extensive inves tigation of workers and of conditions on the manufacturing side of th** asbestos industry and was important on a number of counts. On the meo* cal side the investigation established the occupational cause of asbest.wd** Merewether found that one in four of the sample of 363 workers examine*! had evidence of pulmonary fibrosis attributable to asbestos dust and h* calculated that on the sample, one in eight of all workers in the indtistr would be found to have evidence of fibrosis. It was made dear that t^f 128 McVittie: Asbestosis in Great Britain 129 principal safeguard against the ill effects of asbestos dust in the lungs was (0 be found in improved ventilation and dust suppression, and a number of recommendations were made. * The results-of the report were also important. Under section 79 of the factory and Workshops Act 1901 the Secretary of State issued a certificate te the effect that "the manipulation of asbestos and the manufacture and rvpair of articles composed wholly- or partly of asbestos and processes in cidental thereto are dangerous."-The section in the Workmen's Compen sation Act of 1925, which provided for the application of that Act to work men suffering- from silicosis was extended to certain processes involving exposure to asbestos dost," and in 1931 asbestosis became a eompensatable disease. Compensation cover was fairly wide and the eompensatable dis rate was defined as "fibrosis of the lungs due to asbestos dust or that disease accompanied by tuberculosis." Medical Boards of specially qualified medical practitioners were appointed to make the medical examinations and give the medical certificates, initial and periodical examinations of workers ia certain scheduled processes in the industry were instituted, and the standard of physique required on initial examination was prescribed.13 Special regulations which defined asbestos as "any fibrous silicate," lay down specific instructions as to exhaust ventilation, the prevention of .dust gaining access to the atmosphere of workrooms, the damping of fioors and benches, the cleanliness of floors and plants, the storage of asbestos, and the employment of young persons. The regulations'3 came into force with general application on March 1, 1932. Case finding in Great Britain then has arisen mainly in two ways -- from the statutory periodical examinations carried out in certain high-risk oc cupations is the industry, and from examinations following applications for compensation under the Workmen's Compensation Acts and claims for disablement and death benefit under the Industrial Injuries Act,14 which superseded the Workmen's Compensation Act of 1948. Under the Industrial Injuries Act the words silicosis and asbestosis *ere dropped and the comprehensive term pneumoconiosis was introduced. Pneumoconiosis was defined in the Aet as "fibrosis of the lungs due to silica dust, asbestos dust or other dust...." The Act provided that the effects of tuberculosis (pulmonary) in a person suffering from pneumo coniosis were to be treated as the effects of the pneumoconiosis. Cover was provided for all the main occupations in the industry: (a) the working or handling of asbestos or any admixture of asbestos; (b) the manufacture or repair of asbestos textiles or other articles con taining or composed of asbestos; (c) the cleaning of any machinery or plant used in any of the foregoing operations and of any chambers, fixtures and appliances for the collection, of asbestos dust; 130 Annals New York Academy of Sciences ' (d> substantial exposure to the dust arising from any of the forego operations. ' The diagnosis and disablement questions arista? on claims for disab ment benefit under the Industrial Injuries Act are decided by the Pne mcconiosis Medical Panels of the Ministry of Pensions and Nation* Insurance. The Panels also advise Insurance Officers bn death claims. Post mortem examinations are carried out in the vast majority of cases and the lungs are always examined by two members of the Panel; thus in a number of cases not seen in life the diagnosis of asbestosis has been made post-mortem. A number of cases have also been found following examina tions under a special benefit scheme for older workers who were rime-barred for compensation under the Workmen's Compensation Acts. The Panels also carry out the periodical medical examinations at the prescribed interval of two years. These different kinds of examination provide the only source of information about the prevalence of asbestosis in the country as a whole. Between 1931 and December. 1363,748 cases of asbestosis were diagnosed in life under the Workmen's Compensation Act and Industrial Injuries Act. TaKX 1 shows the number of cases diagnosed each year under the In dustrial Injuries Act. It shows that the number of new cases is increasing. The average of 45 for the last five years suggests that the incidence rate may be at least five per thousand exposed. Four of the Ministry's Pneumoconiosis Medical Panels account for the - Tasuj i Number or New Cases or Asbestosis Duettoseo jk Left under the Industrial Injuries act, 1948 1950 (9 months) 1951 1952 1953 1954 . 1955 1956 ' 1957 1956 1959 ' 1960 * 1961 1962 ( 1963 Total - 17* 17 15 23 31 48 31 S6 27 37 29 43 52 67 494 ' Detailed statistics of cases under the Industrial Injuries Act were not maintained until April 19S0. McVittie: Asbestosis in Great Britain Table 2 "* New Cases or Asaesroaia 1253-63 Analyzed re Principal Occupation* 131 Principal occupation ~ Grand total No. % Opening, disintegrating fpgtrlflHwy loggers 41 16.6 ) 72 Sprayers ' Mattress makers Others- 13 > 41.0 5( . j 12 Weaving 16 | 21.3 Carding, spinning, etc? ffah pip _ 37 20 ` 8.1 Brake Hmwg 4 1.5 Miscellaneous 27 ' 11.0 Total 247 ''At four Panels--London, Manchester, Newcastle, Sheffield. majority (S3 per cent) of asbestcsis cases. They are also the Panels mainly concerned with periodical medical examinations. In the nine-rear period 1253-2963 these Panels diagnosed 247 fresh cases of asbestosia including 34 female workers. They have been grouped according to the processes in which each was mainly employed and with similar processes grouped to gether. Tasls 2 shows the cases analyzed by principal occupation. It shows that the insulating section of the industry gave rise to 41 per cent of the totaL The occupations of opening etc, carding and spinning, and the miscellane- **4 group which includes maintenance men were important causes of eahestosis. _ Tabu 3 shows whether diagnosis was the result of initial or periodical lamination, or the result of a claim, Weil over half the cases resulted from direct claims, and the majority of these (60 per cent) were from the "listing section of the industry. 132 Annals New York Academy of Sciences * Table 3 New Cases or Asnssrosts Diacnoseo 1933 -1963 Principal occupation Opening, disintegrating Insulating Loggers Sprayers Mattress makers Others Weaving Carding, spinning, etc. Slab and pipe making Brake lining Miscellaneous Tool Diagnosis resulted from Initial or periodical exam. Claim to benefit 24 17 3 69 - 13 5 .T5 13 3 29 8 8 12 22 13 14 104 143 1 33 20 4 27 247 At four Panels--London, Manchester, Newcastle, Sheffield. - Table 4 shows the cases analyzed by principal occupation and date of entry into the industry* The year 1933 was chosen because it was considered that by that date the regulations regarding ventilation and dust control were effective. It is recognized, however, that there were enormous dif ficulties in this regard during the war years. The majority (66 per centJ of the group entered the industry in 1933 or after. Table 3 shows the average exposure and the range of exposure in the principal occupations. The figures of average exposures in opening, and disintegrating and weaving are an improvement on Merewether's figures for these occupations in 1930, but there is ae room for complacency. Since 1933 the disease has been produced over short exposures. In practically very principal occupation asbestosis has developed following exposures of under 10 years. It is still developing. McVittie; Asbestosis in Great Britain -- ... Table 4 New Cases or Assestosis Dtacnosed 12$3 -1963* Ji.XAX.rztz> by Date or Entry into Industry 123 principal occupation Opening, disintegrating Inflating Loggers Sprayers Mattress makers Others Weaving Carding, spinning etc. - Slab and pipe making Brake lining Miscellaneous . Total Entered iadnstgy before 1933 Eatered Industry ` 1933 or after 3 38 Total 41 41 1 2 3 6 Ilf 3 3 10 82 {22% 31 12 3 9 10 2? XT 1 IT 165 (67%) 72 . 13 5 12 16 37 20 4 27 247 (100%) At lour panels--London, Manchester, Newcastle, Sheffield. Tabus 6 shows an analysis by some of the principal occupations and date f entry into the industry after 1950 -- well after war conditions applied. Two of the insulating workers who entered in 1956 had only four years TpnHure. The sprayer who entered in 1953 had seven years exposure. The worker who entered carding and spinning in 1952 had five and one half exposure. One of the sprayers who entered in 1951 and had nine years tsposure has since died and ashestosis was confirmed at post-mortem. Scrutiny of the material suggests that age at entry into the industry not a factor in the development of ashestosis. At periodic and other nominations the facts about duration of exposure and dates of exposure **0 be elicited, but these examinations have not so far provided the means rrlatinf working conditions as measured by dust counts, to development f the disease. The tables, and the knowledge of the processes involved in i. r- . K H i 134 Annals New York Academy of Sciences * Table 5 -- New Cases of Assestosis Dugnosq 1955 -1963* {Workers Who Entered the Industry in 1933 or After) Principal occupation Opening, disintegrating Average exposure In years 14 Range oi exposure in years 4-20 Laggers Sprayers Mattress makers Others Weaving Carding, spinning, etc. Slab and pipe malting Brake lining Miscellaneous 28 8.3 11 13 . 15 18 18 14 18 ' 8-44 3-12 5-22 . 9-27' $-23 6-2T 5-30 12-18 4-26 At icur-Banels--London, Manchester, Newcastle, Sheffield. the principal occupations suggest that development of the disease was re lated to dustiness of the job. Scrutiny of the working histories suggests that "range" of exposure depended on. for Instance, whether raw material was freely handled, whether laggers and their laborers made mattresses on the site and broke down old asbestos lagging, and whether high speed cutting and sawing were carried- out in the sectional departments. Dieiffruxtic Criteria ' Diagnosis was made on adequate exposure to asbestos dust plus two positive findings from the following --- presence of basal rales, finger club bing. radiological appearances and pulmonary function studies. Experience has shown that in some occupations recent exposure of three to four years is adequate, and this may be related to type of asbestos. Generally speaking, however, something like eight yean exposure is re quired. On the other hand, very short past exposures 20 years ago are also adequate. - McVittie: Asbestosis in Great Britain Tablx 6 New Cases or Asbestosis Diagnosed 1955 -1963* Analyzes r Principal Occupation and Date -- or Exrxr into the Industry atter 1950 135 Tear worker entered industry principal occupation___ =ir "1952 1953- 1954 1955 1956 Total Opening, dlsinte^jntiisf i- - 1 1 ' 3 InsuhUing Sprayers ___ ] .Ir'l -JT-- - 1 Mattress makers__1 >T, - --- 1 4 2 Weaving Carding, spinning, etc. - 1 i1 - -' i "3 H -- -- - 1 2 5 CTah and pipe saklfig 2 ' - - *- - - 2 Total .7 4 --7 -w- - i 4 18 *At four Panels--London*; Manchester, Newcastle, Sheffield. ' Characteristic persistent.crackling rales at the bases were very commonly present. Flayer clubbingrthoogh-not-so-oominon as basal rales, was noted in 35 per cent of the total. This finding, however, was subject to inter and intra observer error. . ... . " " '* ----- - The radiological appearances were very variable. A large number of films showed the changes characteristic of interstitial fibrosis or of pleural thickening, or both. A honeycomb appearance just above the diaphragm. * "ground glass'* appearance made up of linear markings and small discrete opacities in the lower lobes, obliteration of the costo phrenic angle, shaggy heart shadow, and thickening of the Interlobar septae were common find ings. Calcified plaques were also fairly common and were seen mainly in the films of insulation workers. The Pneumoconiosis Medical Panels con sider that bilateral calcified pleural plaques are almost diagnostic of as- bestosis. The absolute symmetry in many eases and the slow progression can hardly be explained except on the basis of occupation. The Pneumoconiosis Medical Panels had found that workers with as- Wstosis had little tendency to asthma and other forms of airways obstruc tion but that they did not do a stepping test weft. The pathology of ubestosis -- the small firm lung that stands up on the table, that cuts with * dean edge, that shows parenchymal fibrosis without significant pleural 136 Annals New York Academy of Sciences thickening, or shows marked pleural thickening without or with very slight macroscopic parenchymal fibrosis but with extensive microscopic fibrosis suggested that a useful diagnostic aid and a much better assessment of disablement would be provided by using multiple tests. Since I860 the Panels have referred asbestos workers to special centers for full investi gation of lung function. The tests have shown a highly characteristic and consistent combination of changes, e.g. small inspiratory capacity, M.B.C. well maintained for lung volume, high F..V.ftV.C., reduced diffusing capacity, and loss of compliance. These are specific to a small group of diseases, of which asbestosis is one. The disablement at the date of diagnosis was assessed as slight in 140 eases, moderate in 81. and severe in 2S. Two cases were complicated by active tuberculosis at the date of diagnosis, two by pleural tumor and two by carcinoma of the lung. Follow Up Of this series of 247 cases 59 have died. The average age at death from all causes was 57 years. One death was not reported to the Pneumoconiosis Medical Panel and in one other case there was no post-mortem examination. The causes of^eath in the remaining 57 were as follows: . ' Asbestosis (cor pulmonale) Asbestosis + acute pulmonary infection Cancer of lung * Mesothelioma of pleura Mesothelioma of peritoneum Other cancers Coronary artery disease Other cardiovascular conditions Acute intestinal obstruction Acute mtninzitis Mesenteric thrombosis 8 9 21] >40 per cent 2J 1 3 5 5. ` 1" 1 1 la three cases the diagnosis of asbestosis was not confirmed post-mortem. In one with a history of 12-years exposure to dust in coal mines and an adequate exposure to asbestos dust, the slight radiological changes were due to coal miners' pneumoconiosis. In two coses the diagnosis of asbestosis during life was based mainly on a low diffusing capacity. Post-mortem examination showed oniy gross emphysema. Excluding these cases the average age at death of those who died from asbestosis was 57. The average age at death of those who died from cancer of the lung or pleura was 55 and the avenge age of those who died from other causes was 50. These findings are similar to those in I3S consecutive post-mortems on asbestos workers in the area on the London PaneL The average age at death from --McVittie: Asbestosis in Great Britain 137 ^11 causes is the London group of 106 males was S? and of 32 females 58. The average age at death of the males who died of asbestosis or asbestosis *tius infection was 56 and of females 59. The average age at death of males fco died from lung cancer was 57 and of females 59. Under the National Insurance (Industrial Injuries) (Prescribed Dts- rtses) Regulations, sequelae of prescribed diseases are treated as prescribed diseases. The Pneumoconiosis Medical Panels accept lung cancer as a se* quel* of asbestosis. In view of the abnormally high prevalence of lung ctnetn associated with asbestosis the risk of including lung cancers due U> other causes has been accepted and this attitude seems not unreasonable; la the 21 cases who died of lung cancer in the 1953/S3 series the average interval between first exposure and death from cancer was 27 years. There was only one in which the period was less than 15 years. This worker entered the Industry at the age of 59 and was exposed to asbestos dust for six years. There was very slight asbestosis pcst-mortem. Was this an in* dustrial cancer? We would appreciate the views of the Conference on this problem. " la addition to the figures of death from lung cancer, four of the survivors in the series are at ^reseat permanently incapacitated by asbestosis and pleural effusion. In two, lung cancer has been diagnosed, and in the other two mesothelioma of pleura is suspected. Seven other survivors are per manently incapacitated by asbestosis and "bronchitis." and one is per manently Incapacitated by asbestosis and tuberculosis. Scrutiny of the benefit history sheets (giving certified cause of incapacity) of the other survivors, shows that asbestotics are frequently incapacitated for long periods by "bronchitis" and "chest infection." However, a small number have reached retiring age without severe disablement and 27 have had no recorded chest illness since 1955. Initial and Periodical Examinations Against this background of the effects of asbestos dust the role of initial and periodical medical examinations of workers must be considered, Our Pneumoconiosis Medical Panels consider that these examinations of as bestos workers are the most worth while of all. No doubt the workers are happier when they see that they are being kept under observation by the Panel doctors. Reguiar visits to factories afford Panel doctors opportunities to meet factory doctors and to study the processes at first hand. Asbestosis is the most difficult of the pneumoconioses to diagnose and periodical exam inations provide experience in film reading and in the clinical aspects of the disease. In this regard the initial X-ray and lung function teats carried out when the worker enters the industry can be used as controls. May these examinations, however, give rise in the industry to a false sense of security n the idea that the doctors have everything under control? What evidence 133 Annals New York Academy of Sciences is there that periodical examinations have prevented the development o: asbestosis and its sequelae? As regards initial examinations the Pneu moconiosia Medical Panels have to decide whether new entrants are suitable for employment in the industry. The question that should be asked i* whether the employment is suitable for the worker? In our experienct very appreciable improvements in working conditions have been made ii some sections of the industry by some employers. What some can do. other can do. Let us remember the answer and the warning given by Merewethc 30 years ago. When asked whether two years exposure was sufficient t cause asbestosis in a young girl, he replied. "Yes, if she lives long enough.' References L Murray, H. Montague. 1907. Report of the Departmental Committee c Compensation for Industrial Diseases. Minutes of Evidence, Appendict and index. : 127. 2. Cooke, W. E. 1924. Brit. Med. J. 2:14?. . 3. Oliver, T. 1927. J. Indus. Hyg. : 9. 4. SSLQt, H. E. 1928. Brit. Med. J. 2:982. 5. Burton Wooo, W, 192S. Tubercle. 10:353. . 6. ElL3Ian,P. 1930. Proe. Roy. Soc. Med. .. 7. McDonald, Stuart. 1927. Brit. Med. J. 2: 1025. 8. Stewart, M. J. 1930. J. Path. Bacteriol 33:84S. 9. GloyNE, S. ROODHOUSE. 1929. Tuberele. 10:404. 10. MntEWmiSR, E. R. A. & C. W. Price. 1930. Effects of Asbestos Dust <* Lungs and Dust Suppression in the Asbestos Industry. H. M. Stationer Office. London, England. 1L WORKMEN'S Compensation (Silicosis and Asbestosis) ACT. 1930. 12. Silicosis and Asbestosis (Medical Arrangements) Scheme. 1931 13. Asbestos Industry Regulations. 1931