Document 6wMgynEe3mqVYjXjdMQYo6Gvm

FILE NAME Kent KNT DATE 1953 DOC KNT131 DOCUMENT DESCRIPTION Book Excerpt - Recent Advances in Pathology Asbestos Talc and Other Silicates RECENT ADVANCES IN PATHOLOGY SIXTH EDITION By Various Authors Edited by GEOFFREY HADFIELD M.D. F.R.C.P. Sir William Collins Professor of Pathology Royal College of Surgeons of England a eo ae yn sn ime a nerpgymahap With 86 Illustrations a New York 1953 LUDFORD R. J. and BARLOW H. 1945. Cancer Research 5 257 MACCALLUM W. 1903. Bull Johns Hopk Hosp 14 105 PARSONS R. J. and KIDD J. G. 1936. Proc Soc Exp Biol and Med 35 441 PARSONS R. and KIDD J. G. 1943. J. Exp Med 77 233 PASSEY R. D. D--...OCHOWSKIL. REED R. and ASTBURY W. T. 1050 Biochimica et Biophysica Acta 4 391 PORTER K. R. and THOMPSON P. 1948. J. Exp Med 15 PULLINGER D. 1949 Lancet ii 823 PULLINGER D. 1952 Brit J. Cancer 6 69 Research Conference on Cancer A.A.A.S. for Advancement of Science 1945 Washington D.C. Rous P. 1911. J. Exp Med 13 397 Rous P. and KIDD J. G. 1938. J. Exp Med 67 899 Rous P. MURPHY J. B. and TYTLER W. II 1912. J.A.M.A. 58 1840 RUSSELL B. 1910. J. Path Bact 14 344 SELBIE F. R. 946 Brit J. Exp Path 27 143 SHOPE R. E. 1935 Proc Soc Exp Biol und Med 32 830 SMITH W. E. and Rous P. 1945. J. Exp Med 81 621 " A Symposium on Mammary Tumors in Mice 1945. Washington D.C. " Les Ultravirus des Maladies Animales 1943 Paris WOGLOM W. H. 1913. " The Study of Experimental Cancer New York CHAPTER VII THE CAUSATION OF CANCER FURTHER CONSIDERATIONS SOCIAL AND RACIAL FACTORS IN CANCER THE influence of hygiene occupational environment and social status on the incidence of cancer has been the subject of a fas- cinating series of papers by Kennaway and his workers 1947 1948 1949 Cancer of the Lung This disease has increased sixteenfold from 1921 to 1945 in males in England and Wales whereas cancer of the larynx showed little change In attempting to explain this great increase of lung cancer Kennaway came to the conclusion that " although the incidence of lung cancer on those occupations where there is exposure to road dust bearing in mind tarred roads . . " is rather above the general level it seems very questionable whether the recent increase in this disease among the general population can be attributed to the tarring of roads For scores of years before this increase began coal was being discharged into the atmosphere in the form of soot by the domestic fire in quantities vastly greater than any that could now be derived from roads Tarring of roads has undoubtedly increased the amount of dust derived from tar in the air but this increase appears negligible in comparison with the amount of soot already present < Cotton spinners show an especially small liability to cancer of the lung although they inhale air sprayed with an oil which produces cancer of the skin " The high mortality from cancer of the lung in towns Stock the low mortality in agricultural occupations and the absence of social gradient Stevenson are compatible with an ^tiological factor in the air such as coal smoke Kennaway 1947a is led to conclude that " coal smoke does not account well for any recent increase in cancer of the lung One must look therefore for some other factors to explain the increase if there is a real increase in cancer of the lung in recent years Many such factors have been suggested e.g. influenza tobacco popular drugs tarred roads exhaust gases and other emanations including lead ethyl motor vehicles 143 222 DISEASES OF THE LUNG ASBESTOS TALO AND OTHER SILICATES 223 Pneumoconiosis due to Silicates of serpentine the chemical equivalent of asbestos the dust is inert Fibrous Silicates Asbestos Talc The question as to The association of carcinoma with asbestosis has been mentioned whether silicates are toxic when inhaled has been very much above but more details may be given here An analysis of 235 debated since Jones 1933 put forward the view that sericite a cases of asbestosis is given in the 1947 report of the British Chief potassium aluminium silicate is the cause of much industrial Inspector of Factories Cancer of the lung or pleura occurred in silicosis Of recent years however his view has received very 31 13.2 per cent average age 52.1 years These figures were little support Certain silicates are noxious and the chief of these is the group of fibrous mineral silicates known as asbestos contrasted with the much lower incidence of cancer of the lung in 6,884 cases of silicosis of whom 1-32 per cent had carcinoma There are two views regarding the mode of development of average age 59-4 years A high incidence of tuberculosis was asbestosis According to the one the action of the dust is also associated with asbestosis and the Inspector of Factories chemical; the other view supposes that the asbestos fibres act found 72 instances in 130 cases of asbestosis mechanically Experiments carried out at the Saranac labora- Talc Numerous cases of pneumoconiosis due to tale hydrated tories Trudeau Annual Report 1948 do not support the chemical magnesium silicate have been described in different parts of the theory since aluminium hydroxide which neutralizes the toxic world and the first of this type in Britain proved by autopsy action of quartz does not prevent asbestosis Moreover asbestos was reported in 1949 McLaughlin et al Throughout the lungs iz fibres shorter than 20 were found to be relatively innocuous there were grey nodules which had coalesced in some places 3 i whereas if the action were chemical an increase in potency would especially in the lower lobes Microscopically the nodules showed E ij have been expected with reduction in particle size below 5...as whorling but this had not the typical appearance of silicosis in the case of silica A comparison of the effect of asbestos fibres Within the nodules were fibre structures up to 40...in length 15...long with those 2.5... long King et al 1946 showed that arranged singly and clumps Some were very similar to asbestos rabbits receiving the long fibres developed a nodular reticulin bodies and the appearances suggested that tale pneumoconiosis formation comparable with experimental silicotic nodules ; and asbestosis are similar diseases and that the former may be animals receiving the short fibres developed a diffuse interstitial caused only by the fibrous varieties of tale Asbestos is more reticulin formation The localization of the asbestos lesions actively fibrogenic than tale and this might be due to the higher appeared to depend on the size of the fibres with long fibres proportion of fibres in asbestos In New York State disabling too big for removal by phagocytes the reaction resulted in the pneumoconiosis occurred in 14.5 per cent of the workers in the formation of connective tissue within the alveoli with shorter tale mining and milling industry Siegal et al 1943 The dust fibres capable of being taken into the alveolar walls there was contained fine straight needle fibres The tale fibrosis was diffuse interstitial fibrosis These workers suggest that if the associated with an increased susceptibility to tuberculosis fibres were shorter than 2.5...they would be completely removed Glass Wool Glass in the form of fine fibres is being used in from the alveolar walls and fail to produce fibrosis Johnstone increasing quantities for heat insulation and during its preparation 1948 concluded from clinical investigation that workers exposed and use the atmosphere may shimmer as a result of floating fibres to high concentrations of extremely fine asbestos dust did not No harm appears to result however from exposure to this dust suffer from asbestosis The Saranac workers conclude that since the fibres do not remain suspended in appreciable concen- asbestosis is caused by mechanical irritation from the asbestos tration owing to the high electrostatic charge on them Gardner fibres during the movements of respiration and that this 1942 considers that the material has not the properties required peculiarity is related to the flexibility of the fibres not possessed to produce fibrosis by other foreign bodies The view that movement of the lungs is a factor is supported by the absence of reaction to asbestos in fibrous Silicates Fuller's Earth ; Mica Fuller's earth composed mainly of a silicate of aluminium is found in organs other than the lung Gardner 1938 Wyers 1949 points Surrey where it is quarried dried and crushed Middleton 1940 out that if the fibrous character is absent as in the case has given an account of the radiological and pathological changes empriantg nF