Document ZLjaZXdJN2B2pJZQMg17vpjZ

FILE NAME Brakes BRK DATE 1963 Jan 19 DOC BRK018 DOCUMENT DESCRIPTION Journal Article - Asbestos as a Modern Urban Hazard rr a a Aten oon bamalStele ad id j | \ a 1963 S.A. TYDSKRIF VIR GENEESKUNDE 77 uf : ASBESTOS AS A MODERN URBAN HAZARD JG THOMSON Department of Pathology O. C. KASCHULA and R. R. MACDONALD . Pathology Medical School School University of Cape Town aminity report by one of us has been We We asse ation between mesthelioma mesthelioma of published pleura or ritore m and a limited pulmonary asbestosis confined 1 V cm or so of the lower lobes in people e had wo? story of occupational or industria exposure 1 resto It was stressed that these cases had no clinical digial evidence of asbestosis and that the limited asbest s was usually lungs were examined missed at autopsy Even if pueroscopically the local stosis would again be missed unless sections were en hom the bases of the lower lobes The association regarded as an aetiologica one in that there was in asbestosis of carcinogenic concentration effective The plura or on the peritoneum which is no more few millimetres uchi of any size are distant present over the diaphragm No in this thin strip of basal nly ronchioles without glands onchal carcinoma the more usual and consequently result in classical MATERIALS AND METHODS 1 From each lung a smear 25 25 cm microscope slide was made on a x inch 75 by usually consisting mainly of blood and quite thick This was mounted with balsam or dried balsam flooded with xylol and coverglass substitute under a large Initially the smears were made from.apex to base of lung but the majority were from the bases of the lower lobes only The yellow asbestos bodies seen with the power of the were readily and confirmed by the 4 mm miocbjreocstciovpee 1Co6unm tim ngobfjoercto in ve e slide only was done by power fields and in those re- corded as negative 300 power fields were examined we saw a small black carbon Rarely particle with a yellow coating usually circular in form and readily distinguished from the true asbestos body and nothing was seen in these smears giving any real resemblance to a genuine asbestos body Smears were taken from consecutive Groote Schuur Hospital Cape Town autopsies from the years and over to a total of 500 of whiocnh s6u0 bjectwsereagemdale1s5 RESULTS custrial asbestosis is not to be expected husic bres in the lung or some of them are con- alien asbestos bodies by the deposition of yellow Jes en and iron producing an easily recognized ite characteristic structure But before this happens no mest of the very thin and sharp asbestos tend to move down towards the bases owing to movements and grty grty Once the fibre has become cota 1 dy is unlikely to move further It is too t o be transported by lymphatics and its sharp points ow blunted by the p orein globules enorously enorously increased world consumption of as from 200,000 tons in 1934 to 2,400,000 tons in is used o obvious as floor in a ones tiles wide variety of industrial products such as asbestos roofing roof tiles pipe insulation and electrical insula- o less obvious ones of plasik materials where shestos cement etc It is sed to all is possible for anufacturing selling and using these products to - asbestos fibres although their occupat ons 1 not labelled or recognized as ones in are in which os a hazard to be We anticipated do not know percentage of the world. consumption consumption of asbestos * factories other than those labelled asbestos but suspect that it is becoming more and more cant The method used to demonstrate these asbestos bodies is subject to certain variables the most important of which is the extent to which pulmonary oedema is present When is marked enough fluid from a small number c air vesicles is sufficient to cover the shde and a of basal pulmonary congestion will ha e a simsielvaerrebudteglreeses marked effect None of the lungs thus examined was from medicolegal autopsies many of these were for dying suddenly and few lungs in this series were wiptehoopulte some pulmonary oedema and congestion The amount of Jung thus examined for asbestos bodies was the positive findings should be assessed in thattriflligihntg aWned suspect that the percentage of lungs showing these asoestos bodies could be brought to much higher figures if larger samples of lung juice were examined Even so the per- centage positive is surprisingly high and we can regard our suspicions that inhalation of asbestos is a hazard of modern urban life as having been confirmed Over quarter of the lungs of 500 consecutive autopsies on subjects of 15 years and over showed asbestos bodies by the method used 26.4 -- 132 cases - a uch higher figure than anticipated when the investigation was started We expected a higher incidence in the male and this was found 30 but the proportion of females whose Jungs were positive was also strikingly high 0 Table ) wther it is possible that the inhalation of a relatively number of asbestos fibres over a long period several indued a lifetime may result in a focal con- at the lung bases in people who have no ational risk from asbestos murely because asbestos arly asud in towns * the air and citie- and is a likely con- ware able to find any figures in the literature re quency of asbest . bodies in the lungs in routine o> end in 1960 an nvestigation was started to see DATE * of asbestos was in feed an urban hazard and 1.115 establish same same sort of standard with any change i: the future frequency Further differences were evident in the three racial groups in Cape Town from 16 in the Whites to in the Africans with the Coloureds 58 occupying an inter- nediate position with 23.7 of autoosies positive for aspestos bodies In males only 306 cases these racial differences in frequency were more evident Whites 7-9 Coloureds 292 and Africans 61-7 In both sexes and in all three racial groups there is the anticipated use in frequency with age Table II .rom one ranging positive in the under to approximately 30 in those over 65 group <4 J) years of age one surprising feature is a lower frequency in the 45 year age group present in both sexes as shown in t 1 2 Date 1/1/85 1/1/85 by AAC Ne . he a A chat 3 asi) = : > . oe . . . t . 76.18 76.18 A. MEDICAL JOURNAL 19 January ? TABLE 1. THE FREQUENCY OF ASBESTOS BODIES IN BASAL LUNG SMEARS IN THE THREF RACIAL GROUPS Cases examined Cases positive Male 140 17.9 25 Whites 12 224 16.5"37 Male 106 29.2 31 Colouredy Female 84 16.7 14 Africans All races Cases examined Cases positive Male 60 61.7 37 Female 26 50 13 Total 86 58.1 50 Male 306 30 93 Female 194 20.0 39 Total 190 23.79 45 Total 500 26.4 26.4 ( Age groups years 15-24 . Positive < . Negative 252-5-34 3254-34 Positive Negative 35-44 ' Positive ... i Negative 54 Positive { _ Negative 55-64 r Positive ' Negative ' Positive * Over 65 Negative TABLE 11. THE FREQUENCY OF * ASBESTOS BODIES IN BASAL LUNG SMEARS IN AGE GROUPS Male %0 100 4 28.6 2 71.4 5 22.2 2 77.8 7 9.1 3 90 30 19.4 7 80 29 21-6 11 78.4 40 Whites Female %0 100 2 33.3 2 0 100 6 11.1% 1 88.9 8 16 4 84 21 13.%9 5 86.1 31 Total %0 100 6 30 % 4 6920 6920 9 39 2 86-7 13 9.5 14 90.5 38 18.0 11 82.0 50 20.8 16 79.2 71 Male %0 100 7 13-3 2 86.7 .3 38.2 8 61.8 13 20.0 $ 80.0 20 36.8 7 63-20 12 47.4 9 52 % 10 Coloureds Coloureds Female '0 100 5 12.5 1 87.5 7 9.5 2 90 Total # % 100 12 %( 87.0 10 6-7 1 93 29.4 5 39 12 70 12 -7 124 27.8 5 : 378 114114 72.20 13 ~. 23 Age groups years 15-24 25-34 Posiuve < Negative : ' Positive 1 1 Negative <Positive 35-44 s i Negative { Positive 45-54 | Negative F Positive 55--64 55--64 { . Negative f Positive Over 65 _ Negative | Male 25.0 1 75.0 3 50 4 50 4 43.8 7 56.2 9 78.6 11 21.4 3 77 10 23.00 3 80.0 4 200 1 Africans Female %0 100 1 33.3 1 Total 20.0 1 80.0" 4 45 ... 15...1 66.7 2 60 3 40.0 2 28.6 2 71.4 5 57.2 4 42.8 3 100 3 %0 54 6 47 6 10 52.4 11 61.9 13 38 8 70 % 14 30.0 6 87.5 7 12.5 1 Male 6.7 1 93 14 26.6 8 73.4 22 37-1 17 62.9 29 26.4 19 73-6 53 35 24 64.7 44 32.0 24 68.0 51 All Faces Female Total 0 ...1 100" 8 95-6 22 23 4 25.6 12 76 744 35 15 6" 5 28-2 22- 84.4 27 - 12.9 4 87.1 27 26.5 13 22-4 23 77 80 31 73.5% 36 22%.18 3 77 44 68 % 80 28.0 % 37 72.0 19 Januarie 1963 A. TYDSKRIF VIR GENEESKUNDE 79 % 100 . 100 % 4 ___ AFRICANS 50 (meee i . 50 4 MALES we te FEMALES COLOUREDS WHITES 15-24 25 34 35 44 45 54 55 64 65 YEARS 15 24 25 34 35 44 45-54 55 64 65 YEARS Fig 1. Fig 2. Percentage of cases Percentage of cases positive positive for for asbestos asbestos bodies in bodies in age groups all races age groups males only In males only 306 cases this is striking in Whites and Coloureds but in Africans the drop appears one decade earlier Fig 2 and is based on smaller numbers The appearances suggest that there are two curves that of the young which if extrapolated would reach 100 by the age of 60 and that of those two decades older who were less exposed to the inhalation of asbestos fibres in their youth and avoided the undue exposure from 45 years onwards Otherwise we woul have to presume that after the am of 35 a significant number of formed asbestos hodie lose their encrustation of protein and iron and return aouk oo the state of asbestos fibres in ot be seen or recognized in which form they smears Another possi the y just as difficult to establish or to refute is that older age groups there is a less marked or slower response to the presence of asbestos fibres and a smaller proportion of those inhaled is converted into asbestos odie Th + can be little doubt that those under the age of 15 e had better opportunities of inhaling asbestos hrshan hrshan the older age groups in their first 35 years owing to the increased and nfore widespread use of asbestos The world consumption of asbestos 35 years ago was less than eighth of what it is today and the houses and public buildings in Cape Town generally contained relatively little asbestos The city has since more than doubled in size and population and the new buildings public and private contain much larger quantities of asbestos in various forms In addition much of the in- ustry using asbestos in this area is of new growth or recent development as it is ur almost every part of the sternized world in conformity with the marked increase in world consumption of asbestos in the last 30 years It is not difficult to suggest reasons why those of 45 years and older at death did not inhale as many fibres as did those in the younger age groups in the same period of time A higher proportion of these older people would not be employed in occupations involving hard physical work as is required in the manufacture handling or use of many containing products more would be ir administrative posts and some would be retired What are the possible means by which asbestos inhaled to produce the asbestos bodies Firstly those employed in asbestos factories or in South fibres are we have Africa at least as pointed out recently by Wagner et al those who work in asbestos mines or who live in the vicinity of the mines have or where the asbestos from the mires is treated or handled This is of necessity a restricted group Secondly we have those who may be exposed to asbestos fibres in factories no designated asbestos factories where asbestos is used These constitute a surprisingly large and increasing group such as cement works asbestos cement and all the factor where asbestos is used in the manufacture of asbestos roofing tile millboard friction materials such is brake linings ceiling boards insulation and packing for pipes and boilers for electrical insulation and the many other ways in which asbestos is employed as an addition to all sorts of plastic materials A much larger group of people who deal with or handle such materials degrees ranging from may be similarly exposed to the occupational exposure of varying builders and builders labourers to the handyman in his home workshop For example a garage worker would not ordinarily be regarded as a candidate for asbestosis of any degree yet Brugsch and Bavley reported recently pulmonary asbestosis in a garage worker employed in spraying underbody coating containing 50 of asbestos We suspect that the number of people in modern urban community who are thus theoreti- cally or practically hable to inhale asbestos fibres is a very TABLE 1. THE CONCENTRATION OF ASBESTOS BODHS IN BASAL LUNG SMEARS , 4 1 Asbestos body in 31-300 L.P.Fs. a i Asbestos body in 10 30 L.P.Fs. a . * Asbestos body in 2-9 L.P.Fs. . . * More than 1 asbestos body per L.P.Fs. .. Male ee 16 oe 4 .. 4 . j Whites Female 2 1 0 Total 25 6 5 1 Male 21 4 3 3 Coloureds Coloureds Female 10 1 3 0 Total 31 way way way : . I Asbestos body in 31-300 L.P.Fs. 1 Asbestos body in 10-30 L.P.Fs. ? Asbestos body in 2-9 L.P.Fs. . Were than 1 asbestos body per 2 L P.Fs .. Africans Male 21 9 5 2 Female 11 2 0 U L.P.Fs. -- power fields Total 32 11 ... 2 . Male 58 17 12 6 All races Female 30 S 4 0 Total 88 22 16 6 80 S.A. MEDICAL JOURNAL 19 January 1963 percentage significant of the population but cannot even put forward a guess as to what the figure is Lastly we have those with employments not obviously associated with asbestos These constitute presumably the largest group of all yet the results of this investigation clearly indicate that they also inhale asbestos fibres To try and place our positive cases into these three groups would appear an impossible task since details of occupation are meagre and in any case many of the Coloureds and Africans have had varied occupations and only the last is noted But in Cape Town the occupations of the three racial groups are restricted to a greater extent than in most cities There are virtually no labourers who are White and the occupations of the African males have a relatively narrow range those of African females are narrower still A crude assessment of the relative number of asbestos bodies is given in Table III It should be stressed that these are quantitative only to the bases of the lungs and not to the lungs as a whole In the great majority over 80 of the positive cases the bodies were scanty one body in 10-300 power fields In 22 cases 4.4 of those examined and % of the males the asbestos bodies were numerous from more than one per power field to 1 in 9 power fields These are likely to be cases in which industrial or occupational exposure to asbestos has been present and if that inference is correct it is disturbing that 1 in 17 of the population of Cape Town of 15 be thus affected The admissions males of the hospital years and over should to the Groote Schuur Hospital are fully representative of all ethnic groups in Cape Town but not perhaps of all social groups in the Whites In Cape Town African females are rarely employed except as domestic servants and as expected none are found in the group with abundant asbestos bodies Only 4 were females while 18 were males a finding again in favour of occupational exposure as the explanation Unfortunately tissue for microscopical examination was not taken a precise as a routine from the bases of the lungs and correlation between the presence of asbestos bodies in all and a limited cases sections basal from asbestosis is not the lungs were possible available But for study and 3 examples of ordinary classical asbestosis were found 1 mild and 2 of moderate severity In only 1 of these was a history of exposure to asbestos obtained one year's employment in an asbestos factory 15 years before his death from lobar pneumonia and that was obtained from relatives as a result of persistent enquiry In 2 further cases sections had been taken from the lung bases and both showed a limited basal asbestosis with bilateral basal pleural thickening but the lungs elsewhere were free from fibrosis and showed very scanty asbestos bodies Of the remaining 17 cases in this group we do not know how many would have shown this basal asbestosis had sections from the lung examination All bases been one can say available for is that in the histological sections of lung taken at autopsy from areas other than the bases asbestos bodies usually scanty were demonstrated i 9 but in none was there fibrosis or pulmonary asbestosis The fact that lung smears from these 17 cases showed asbestos bodies to be as numerous as in the smears from 3 cases of classical asbestosis and 2 of basal asdestosis leads us to suspect that most would have shown the basal asbestosis had sections been taken from the lung bases We find it difficult to believe that the majority of those with abundant asbestos bodies worked in asbestos factories though no investigation of their occupations during their lifetime was undertaken Only 1 was a builder and no other of the occupations given indicated clearly the possibility of exposure to asbestos We presume that most of them at some time and had contact products in some or other came into the second group with asbestos or containing of the varied occupations already | mentioned - conclusion that is significant er sigh It they were not so exposed occupationally the findings are even more significant and even more disturbing though it should be emphasized that only in the 2 cases of classical asbestosis of moderate severity pulmonary * disability was present and in none of the others were the pulmonary lesions in any way responsible for death But perhaps the most significant finding is the large proportion of cases in which fewer asbestos bodies were demonstrated 11 in 4 of all the remaining autopsies In most of these the bodies were scanty but quite character- istic and we wish to stress that there are no grounds fer regarding these as asbestos bodies merely because their presence may be regarded as difficult to explair We do not think that there is any difficulty in explaining their presence and indeed would go so far as to y tha their absence would be the more remarkable finding in the average urban dweller of adult age in westernized communities In recent years the term asbestos 1 My bas been altered by some to asbestosis body an un tunate and unwarranted change because the great majority of Jungs which show asbestos bodies have no pulmonary asbestosis at all as these findings clearly demonstrate The varying frequencies in the three racial grors grors and the the for two sexes give some indication of the means by which asbestos fibres are inhaled The overall positive figures the sexes are 30 male to 20 female If we exclude those with abundant asbestos bodies as being the resul of occupational exposure the resulting figures show little variation between the sexes in Whites and Africans White males 14.8 White females 13 African males 57 African females 50 but the difference in the Coloureds is increased Coloured males 25 ,, Coloured females 3.6 We find almost identical figures for the Whites male and and this female and the female Coloureds - 14.8 , 13.3 13.6 respectively Are we justified in presuming that is the environmental base in Cape Town no resulting from occupation but determined entirely by asbestos fibres in the air The numbers on which these figures are based are not large but together are significantly lower than the other 3 groups with higher fre quencies P = < 001 And what are the explanations of the much higher rates in Coloured males and Africans of both sexes Occupations with possible exposure to asbestos such as building may account for both the male groups but not for the African females Their environment largely restricted to native locations is the only explanation left to us , we assume as is likely that most of those with scanty aspestos bodies did not develop them as a result of their employment we are left with the home and the air of . ~~ . an 13 Januarie 1963 S.A. S.A. TYDSKRIF VIR GENEESKUNDE 81 The city as the only possible sources for the asbestos ron Poor In the modern home there is no lack of theoretical ssibilities Asbestos roofing or roof tiles ceilings and oor tiles are common enough and the last at least must * subjected to wear and liberation of asbestos fibres insulated central heating pipes so common in the northern hemisphere are virtually absent in Cape Town names but the insulating pad in domestic irons almost universal and usually is made in a soft friable and readily disintegrating form But under ordinary conmans it would seem unlikely that many asbestos fibres inhaled in the average home The air of the street ems a more probable source The average motor vehicle cars out 3 or 4 sets of brake linings in its lifetime and 2 consist mainly of asbestos which is ground to dust - the linings wear This alone would involve in most . es the discharge of tons of asbestos dust in the streets ery year The disintegration by natural weathering of + containing products from car underbody coating asbestos cement roofing must again result in asbestos res getting in the air of towns and cities ut perhaps the most important factor is that asbestos ally indestructible It resists heat alkalis acids and : means by which materials are altered chemically or cally and mechanical disintegration merely results " : ion of finer fibres more liable to be inhaled A ngerous when inhaled than larger fibres assesses the hazard of inhaling asbestos exists today as a trifling matter or as a gnificant one it must become greater with sats The half of strontium 90 is 28 years but fe fe of the asbestos fibre is an infinity of years + 000 tons of asbestos used cach year are added Tons ' Tons of tons used in oportion becomes previous years and even available as an con- rt was the actual amount will increase as more . - mulates on the surface of the earth The weathering and disintegration of some asbestosng products is likely to be very slow but many oe elatively new and may not be as lasting as rected We can only guess what proportion of borne hests fibres is rendered innocuous by dispersal or reew sed by fresh or salt water but whatever the proportion 4likely to be one that is more or less fixed and we .a mer think that the total amount of borne asbestos e in cities will do other than increase We do not know of any published figures from other * of the world with which our findings can be comsword but the high frequency of asbestos bodies in routine Papstes is not confined to Cape Town One of us ed a similar investigation in 1961 in Miami Florida ( and even higher positive figures are being obtained most to be expected since proportionately more a wnt cy is of recent growth with a high asbestos art of the buildings and the United States accounts ... ... ug...ly over a third of the world's consumption of crestas de would suspect that even higher figures would " mained in Los Angeles i ts all 100 easy to go to extremes in discussing these ings They could be dismissed as a pathological ty of no practical signific supported by the fact that in only 3 of the 132 cases positive for asbestos bodies was there associated pulmonary fibrosis and disability and in none was there associated mesothelioma of pleura or peritoneum But 5 such cases were seen in the same autopsy service in the previous 3 years and going to the other extreme a lurid picture could be painted of what conditions might be in 30 years time when the accumulation of so much asbestos in towns would lead to much higher concentrations of asbestos fibres in the air The results of long inhalations of these fibres might be almost universal basal asbestosis in adults and a frequency of mesothelioma of pleura or peritoneum higher than that of bronchial carcinoma today It could be added that even if the hazard were then appreciated and all mining and utilization of asbestos ceased there might be no significant reduction of the air contamination owing to the indestructibility of the asbestos already mined and used and its inevitable weathering and disintegration with time The present findings clearly demonstrate that asbestos fibres are being inhaled by urban dwellers but not in amounts sufficient to produce pulmonary lesions or disability In % of hospital autopsies in males aged 15 years and over a high basal concentration of asbestos bodies is demonstrated suggesting that industrial exposure to asbestos is more widespread than expected I would seem almost inevitable that in the future the urban dweller will be exposed to a higher concentration of asbestos fibres We do not anticipate that this will lead to an increase in classical pulmonary asbestosis but more cases of basal asbestosis would seem almost inevitable Indeed even if there is no significant increa- in the amount of asbestos fibres in the an the younger urban dweller will have a lifetime's exposure available for concentration at the lung bases unlike most of those of over 50 years of age today who in their earlier years had little opportunity of inhaling asbestos fibres If we are correct in regarding basal asbestosis as the main aetiological factor in mesothelioma of pleura or peritoneum an increase in this tumour would also follow This possibility is the main justification for the title of this paper SUMMARY ; In smears from lung bases from 500 consecutive autopsies in subjects of 15 years or over asbestos bodies were found in 30 of the males and 20 of the females In most cases this would appear to be the result of tamination of the urban atmosphere and the bodies scanty and not associated with pulmonary changes In 6 of the males the bodies were numerous and conwere were presumably of occupational origin An increase in the amount of urban air contamination would seem inevitable in view of the increasing consumption and diversity of uses of asbestos and of its virtual indestruc- tibility The tendency for asbestos fibres to concentrate in the bases of the lower lobes of the lungs produces a cumulative effect and an increase in the frequency of basal asbestosis is probable This basal asbestosis does not result in pulmonary disease or disability but appears to be of actiological significance in mesothelioma of pleura or peritoneum An increase in this tumour is Forecast and this is suggested as the mut ground for regarding asbestos as an urban hazard REFERENCES 1 Thomson J G 1962 S.Air Med J 36 759 2 Wagner TC TC Sleggs C A. and Marchand P 1960 Med 17 26 3. Brugsch 1 and Barley H 1961 New Enel J Med BritJ Industr , 265. 379