Document jBBGdZ6n3ep1ZmBDY7voRKy3p

FILE NAME: Saranac 7th Symposium (SSY) DATE: 1952 DOC#: SSY013 DOCUMENT DESCRIPTION: Transcript of Presentation by Dr. Fletcher with Discussion rsxm rsm Pifis . 207 Ia afraid tiia ti&la f this '&p&T is & ULttla bit vllcsr >ajan tfest* Strictly spjskizsg, Ia gclas to talk about tfc* Spldsssiology isa Great Britain, because ecssa of tba groat lutarisit io tbs epifiest* iologi'ssl feature* of this dlsaas* is our sewntry, is tb difforaco* lx. tb* prevalfeuo of this dlssoso in different ports of th* countzy. So, first of all, for tfccsa of you vho knew os 208 little about the geography of our country a8 I know about yours, Im going to put a map up to show just where the coal fields are in Great Britain. We have, first, here, ie the country. The coal deposits in Great Britain are here in South Wales with little fields neighboring which are very unimporu-nt in size. Then there is a very small field hidden at the moment. Just coming out there, in Kent, saae little fields in the Midlands, a very big field in York- i shire and another one in Lancashire, a big one up in Durham, going out into the sea, another little one in Cumberland going out into the sea here, and other ones in Scotland. And, where our work has been concentrated is in Wales, but we have also investigated the one up here in Lancashire and the one in Cumberland. By and large, the greater part of the coal in Great Britain here is bituminous, hut in Wales -- next slide -- the coal grades are -- here is the coal field in detail, from anthracite over here through semi-bituminous or what we call steam coal out here, with bituminous coal out n t h e west. There is a complete spectrum of coals in South Wale3 from anthracite to bitum inous . j Now, the disease of coal miners pneumoconiosis that - ?m croing to talk about was ver_ fully described, I should j - i 209. ; say pathologically described, over a hundred years ago in ji Scotland, and the disease then appears in British history I to have disappeared* The experts said that there was no Ji such th.ng now in about 1910, as the old miners asthma, I j! the black lung of miners; it had disappeared and that was j. ; attributed to improved working conditions in the mines. | But then, as radiography began to be more widely 1 applied in Great Britain, it was found that miners showed | X-rays that looked very like silicosis and than the path-- j ologists got interested again, and particularly in South I Wales, described the sort of pathological picture that ; Doctor Vcrwala has described to you, and in 1929, miners ij | were acinietad to Workmen's Compensation for the first time j and some official figures as to the prevalence of this con i dition became available* I And here we start actually going through various j legal delays, the first cases certified were in 1931* These j are years along here (indicating on s lide) and the height ' of the column represents numbers of men officially certi-- j j! fiod with the disease in each year from 193- to 1947* There; U I j is a gap there because the legislation changed, and then j , there is *1+8, *1+9, *$0. This is South Wales where about j j lust over a hundred thousand miners work, and this is the . wnole rest of Great Britain where sev^n ty thousand -- six i to seven hundred thousand, I should say, work; seven times 210. the number of men here* as in Wales* These cases after this gap here are not comparable strictly, because the legislation changed slightly and the standard* of diagnosis changed slightly but not very greatly. You see the steady increase throughout the 1930's and then the very abrupt increase through the war. I'm not going into the reasons in detail; it was partly due to the increase of dust during the pro-war years, due to mechani zation, also due to change of legislation during this time, and also due to the fact that during the war, miners could not got ut of the mines except on medical grounds* Wages went up in many industries and many men found pneumoconiosis a way to get lighter but equally ard uous work, and so legislative, social, I think generally, epideir. ^logical reasons for this tremendous increase* I just want to draw your attention to the incroasu of the size of the problem in South Wales* Tnssa workers increasing during this time, over twenty thousand men ware certified with this disease and removed from the industry. In 1914-5* over one in three of the undeq-ground workers of two mines were removed frera the industry for pneumoconiosis* In great contrast to this tremendous prevalence in South yales, by certified figures, we have the very much smaller prevalence in the rest of Great Birtain. The level 211. seems to be easing off in South Wales; it appears to be still rising in the rest of the country. Well, nov, in South Wales itself, there are also quite important changes in the certification prevalence as we look across the country. Over in the anthracite area here, this is a map in which little dots imply coal mines employing more than a hundred men, and these are contour drawings on mines with the same prevalence of certified 1 disease over this period !+0 to ip5. The blacker they are, the worse they are. The black here is over seventy per thousand per annum, and mostly the anthracite, with a tongue out her in the bituminous area, and the surrounding bituminous area were very much lower prevalence. Well, now, the Medical Research Council did a big investigation of this problem in 1938 and with Doctor Hart and Doctor Haslett and a lot of other people, and they con firmed, from survey work, this distribution of the disease in South wales, the higher the rank of coal, the more the disease. They failed to show any direct relationship to any particular component of the coal such as the tree sil ica or the ash. There was a general relationship to the total amount of dust. The disease, they pointed out, was cults distinct from classical silicosis and from their work, this rank c-f coal hypothesis, that high rank coals, anthracite _____________________ ___________________ 212_._ coals are more harmful than the bituminous coals, the soft coals, that came into being and has had wide currency, and that la Although, as I say, there was no direct evidence from their work, for this hypothesis because the anthracite mines were dustier than the steam coal, which, in turn, were dustier than the bituminous* Well, now, to go on, owing to the very grievous situation in South wales, the Hedical Research Council set up a special unit in 19lf5 which I have had the pleasure and honor of being associated with since that time, sad we have done a good deal of work into tne epidemiological side -- tne epidemiological features of this disease* The work has been done by my colleague. Doctor Cochran, and I really feel rather shy coming here and talk ing to you about work he has done. All that I am going to tell you about has been work for which he hat been respon sible and the credit gees to him and his team. The objective of this epidemiological work has j fesen, first, to try and see if we could get any -..plana- j i tion for these epidemiological differences as shown by : i certification figures, end secondly, to see if we could j t guide dust suppression by establishing safe limits of j dustinoss. : Now, the method -- next slide -- has been to study men and their dust exposure* Now, what sor+ of men 213. did we study? The sort of groups that have been used for epidemiological work have been the following: Miners attending hospital. I'm ashamed aj-raost to put that on a slide, but I wouldn't do it except that quite prominent papers have been published on miners attending hospital* and clearly they are -- even a nighly seleoted group, even if the doctor himself doesn't select his patients -- ttiey have been selected for him on a very curious and unpre dictable basis. A lot of papers have been published on applicantaj or receipts for compensation. All the figures I have ahownj . I you so far as we have gone, are based on that sort of popu-j lation, but again many-fold motives effect a man's applica tion for compensation, and it's difficult to use that type of population for active work. You then have more carefully selected populations. The ideal population would be all the men who have ever worked in an industry, whatever they're now doing, but clearly, that's impossible. What we can do is take select-*, ed cases, all the cases in a mine and selected occupations,: ail the underground workers, all the underground workers j and surface workers, because miners tend to go from under- ; ground to surface from time to time, or complete mining | communities. We have adopted, at various times, the pop- ! uiat.l ans three to six. 234* Now, the next important thing is to insure that you get all the population youre after* Here is, just to emphasize this point, the prevalence of disease according to our categories, 0 , 1 , 2 , 3 simple pneumoconiosis, mass ive fibrosis, to a hundred consecutive cases attending the certifying panel at Collier* You see the first two are not represented, miners and ex-miners admitted to our ward, high proportion have exited; ex-miners in a town, this dis tribution; surface workers, and the designed underground population, and you will see that these three all agree fairly well, but the certified cases and the hospital cases show a gross distortion of the distribution of disease, although all these cases come from the same geographical area* These are the collirr'ys we have studied which have been in South Wales, Some of the collierys already hs.ve been studied by the Medical Research Council in 1938* We have re-read the films in our classification and used their figures. We have also, particularly carefully, stud ied some steam coal mines, this group here in South Wales, Steam coal is cur semi-bituminous, and an anthracite mine with very little disease in it. This is anotner stsam coal; nine, and two mines in England with rather low concentre- i tions of dust, two mines in England in Lancashire and Cum berland with very high dust concentrations repute Jly, frcm all we could hear, but very low certified Incidence* We hoped there to get a real contrast between the conditions in bituminous and anthracite mines in South tfale* and the general relationship between dustiness and rank out side South Wales, to get mines which were really dusty but had low rank coals, and those are the two* Kow, this slide is attributed to Doctor Cochran, percentage of the underground-surface populations which he has managed to X-ray in each of t iob e mines are given there, and the only two cases, in this mine here and here, in which he was not fully in charge of the survey, there were early surveys, is the proportion below ninety-eight percent* The important aspect of that is shown in two figures -- next slide. At these two collierys where we didn't get ninety-eight percent of the population, you will] see that the proportion varies with age* The statisticians! i found difficulty in the casual!, young, and in the equally old* The middle-age you get e- ior. If you don't get ninety-five percent you get seventy-five percent; both of these collierys you got over seventy-five percent of the j population, but you've rot a distorted sample* It is es- j ! sential to get a hund_re ' percent po lation. ; The next slide -- and one colliery where he got ; a hundred percent. Doctor Cochran analyzed the amount of : 216. disease in relation to pneumoconiosis, inactive and clin ically significant tuberculosis, on the radiograph and tho first two hundred men came along willingly for examination.: The second two hundred came along after some argument, and the third two hundred had to be frog-marched In, and you will see that people with pneumoconiosis cccie forth readily, the people with tuberculosis lag behind, so if you only get sixty percent, you have missed quite a lot of your disease. You get adversely distorted samples in relation to disease, 4 problem which is quite often omitted in reference to this point, and -ihich is commonly omitted in survey work. Well, now, some results -- next slide. Eero are Just the crude prevalences of these twelve collierys I have shown you, just the sort of thing you get from X-rays of these populations. Here is an anthracite mine, preval ence Category 1, 2, 3* Massive Fibrosis, PHF is short for that, quite a big range of these prevalences; these* two English collierys with the low prevalence end you will see j | that this does, by and large, conform what is shown by cer tification figures, that if we*re interested in auet ex- j j posure, we can,t use this crude prevalence, and the quss-- j __ I tion is what dust exposure should va examine in relation ! . I to this disease, j This slide shows figures from all these popula- ! tions in relation to age, ye.rs spent underground and yea. 3: spent on the coal face, all lumped together, the whole lot, i i and you wii-. see that in relation to age, there is a t&per-j l ing off after the age of forty-five; there is no increase in the prevalence of the disease. This is Category 1. You take underground work, there is a smaller tapering off; whoh you take miners on the coal face, then there is a steady increase with increasing years on the coal face, and it was that argument and various other arguments that led ua to concentrate our attention in relation to dust exposure to the coal, face worker and tc dust at the coal face. And, wnat we have done is this* For our relation ship between dust and disease, technique of field surveys, we have tha unit, an X-ray town and a dust team* The X-ray team takes the X-rays and takes industrial histories* The X-rays tire read by the duplicate reading technique I spoke to you about this morning* The industrial histories are carefully screened and from it we select pure faces workers* They are defined as men who, during the ten years before j ! the survey, have worked on the coal face for more than one | year and worked in no other dust occupation for more than j | one year. We limit cu. .elves to ten rears because cur dust) ' i exposure may occur today, but the d* sease is produced in j the past* We have, therefore, to multiply by a factor pro-| i duced in the dust history in order to make the dust ccapu- j tation relative to the dust we have observed, and we do not1 218 think we can do that over a greater period than ten years, so wa restrict ourselves to pure face workers over ten years# The dust team goes to the coal faces, all the coal faces in the mine using the precipitator, and they take dust measurements in terms of particles, c, c. or more strictly speaking, and I apologize, per millimeter, twenty-five micrcns, and we have now adopted a technique whereby the dust is not taken at fixed positions on the coal face, but is taken at the working places of colliers selected on a random basis, so that the dust measurements do represent the true measure of dust exposure of those men# If the man selected is an absentee, well, no dust is collected that day and naught is contributed to the average, because the man wasn't exposed to dust that day# We introduced that relationship to the actual exposure of the man as closely as ua can# Then, we take the history of the mine as cl-aaly as we can in terms of production, ventilation, all the rest of it, in order to see how relevant this sample here | , | is to the past and introduce a multiplication factor where ! necessary, but at the same time, through the filters, we , take the analysis and we get an index of total, dust dose | ! exoressed in particles per c. c. times years, that is the j _____________ ____________________ _____ 219*_ concentration of dust multiplied by the number of years the, man has been exposed to it, and on the other side, by multi^ plying that by the proportion of free silica in the dust, we got a total of silica dust* Now, then, this technique of relating dust dosage to amount of disease is a standard pharmacological one, but I want to pay tribute to my colloaguo, Hr, Roach, who has done all our dust measurements, for the fact that he point-! ed out this particular method of expression to use, Doctors,, who ought to have known better* Previously we were Just taking an average dust concentration times an average years of ail t .9 men, but ignoring the great differences in the distribution of period of exposure between the different mines* What Mr. Roach suggested, w should do, is to take for each man the amount of time hs had spent on the coal face, multiply that by the number of years and get, for each man, a dust exposure in terms of particle years, then group the man according to different groups of dust expos- j j tire and see the percentage in those groups showing radiolo-j | gicsl change and this is the result in all the pure face < workers at eight of those twelve British pits where we had j the dust information. Pour of them we didn't do dust I samples* Quite a nice sort of steep curve with the only j dip here. j Well, now, we were interested in the difference 220. between the English mines and the Welch mines, so let's see what happens when we separate them. The dip comes right out and we find b autiful smooth curve, and this curve is fitted by less squares to these figures here which is quite different from the English* These six Welch pits are all mutually consistent statistically, and statistically quite different from the English here. Here is the dust dosage, and they do show a quite clear difference in the relationship of radiologi cal abnormality and dust exposure. Kow, then, why this difference? Well, i t 's natural that we should say 'Hurrah* j it ia obvious that this is silicosis, anthraco-sil :osia; y o u 've only got to look at the Amsrican-Buropoan literature to see that, and it is the responsibility of silica, and so we take these five mines, the five not six, and we look to see* The range in ash content, .nothing much in it; the high content is Inone of the English mines; total silica, nothing in it; free silica, this should be 0U. -- I 'm sorry that's a mis print -- and you see again that the English mines fall in the same sort of range as the Welch Mines; calcium; albumen; and the only ririking thing is the volatile matter. These I Welch mines happen to have this range where both the Sag- \ lish mines have the low volatile. We haven't yet managed ! i to study low volatile Welch mines, so we don't know how | 221,_ important this is, but it's the obvious point at the moment. Well, now, let's just look at the free silica dosage against dust. That's in the six Welch pits, and I want you to remember that other slide, that beautiful stoop curve, and the very visible sigmoid adopted from it, arid it's very clear that the silica is not relating to the ab normalities as well as the total dust. liell, now, what ran this mean, this difference between the Welch and the English mines? I think that in looking for the silica difference, we're really barking up the wrong tree altogether, and for this reason* That in talking about active and inactive dusts the other day, I think I suggested to you, or perhaps I didn't, but it's in my written paper, that you might define an inactive dust as one in which there is a lot of dust in the lung in rslati- to the amount of reaction to it, but as an acfcuve dust is one in which there is relatively little dust in the lung in relation to the amount of reaction. Cork - quite a little cork, produced fibrosis. In coal. In Iron, you get a large amount of dust with rela tively little fibrosis, but If this difference between t'is English and Welch mines, wara bo tween the bituminous and the anthracite and the steam -oal minos, If that were due to differences in the fibrogenic proparti-. of these dusts,j we would expect, p a aologically, to find a greater reaction! 222, in relation to the amount of dust in the Welch mines than we find in the English mines# Now, hitherto, the amount of material w e 've got from English mines is relatively scanty, but we have quite a bit and wo don't see any such differ ence# If you look at an English bituminous miner1s lung. Professor Goffe will say, 'I can see no difference in this lung from a Welch mine - miner*s lung, except there seems to be less dust in it'# The amount of reaction in rela tion to the amount of dust is the same, but there does seem to be less dust in it, and that at present is our thinking, that for some reason or other the bituminous coal dust either doesn't get into the lung so easily or having got in, is easy meat to the phagocytes and they just walk straight out with it again, a very difficult hypothesis to test# W e 're trying to dc that with animal experiments, but it's going to be quite an elaborate statistical problems to get proof of that hypothesis, but that's where w e 'ro sitting at the moment. We think there must be sane differ ence of some kind in the retainaoility of these lusts# I can say straightaway that it doesn't lie in the size dis- j tribution of dusts* { I Well, now, that is as far as we have got in re- j lation to these epidemiological differences. There is this difficulty. We can't yet explain it, and at the time, we ; 223.___ have set for the future, a plan to carry out simultaneous dust and radiological surveys at twenty mines scattered throughout the whole of Great Britain, which the coal board are organizing in collaboration with us, and we hope to overcome the inaccuracies of the historical factor in this way, and from follow-up surveys of this kind, to get really good evidence, more precise than we've got at the moment which, associated with and in addition to, animal experi ments, may help us to solve the why's and wherefore's in this difference we have found# Now, what about safe limits? Next slide# Here we have, for the Welch pits, where our working data is muchj more complete, those dose response curves for Category 1, and for Category 2, and moro and Cateogry 3, and here we have the dust dost# These are sigmoid curves, and are, of course, sound distribution curves* That is to say this curve here represents an ordinary - an or dinary normal distribution curve and the fifty percent point is, of course, the most accurate point to take the rel 'ant point on it from, and I have mentioned in my paper that our ratio between our categories is roughly speaking, but only roughly, linear, | I is about half as much dust again, at the fifty percent | ' i point here; two and three, you can see it isn't quits as i * i accurate as it should be, but it's not bad, and this is our j evidence that our categories are related to dust exposure. 1 Now, then whan I putblished this In the Screed, I shell leave out these figures here, and I hope you will forget them, because obtfiously, this is quite a dangerous graph, because you can read up from here, if a man is ex posed to five tnousand particles per c* c., by the by, a thousand,approximately, particles is, I think I 'm right, aren't I, Professor Drinker in saying i t 's approximately twenty-five to thirty million particles per cubic foot? I know you talk about these different things, but perhaps you better leave it untranslated at the moment* Anyway, a man is translatod to a thousand parti- 3 cloa per c. c, which is about the official approved levels! in Great Britain, for five years, fifty percent of the men j will have Category 1 in five years* Ten years, fifty per cent will have Category 2* Do33 it matter? I think w e 'll leave that discussion until Doctor Hugh.-Jones has told you something about the disability* Clearly, from this sort of chart, you can read off what will happen to nan if they're exposed fco these particular conditions for various periods of tino, and ob vious ly, I suppose to some of us, should forget the politi cs . consequences ana just publish ala results and let the workers and the eiaployors fight it out, but I think that I t 's better at the present, to publish that graph without i j the figures on it for the '-ture, so I hope yo u 'll try to j 225. understand why I omit the figures from the publication# It*s also a matter of discretion, because in these figures we have got our historical factor which is a little bit of guess work, and these figures here are only relevant to the particular range of dust concentrations that we have ob served. We have found, for instance, that if you separately analyze years and particles, that for the same -- sorry, that for - yes, the same period of time, twice the exposure produces more than twice the amount of disease# That is to say concentration is more Important than time and the se figurea Just represent an even weight of concentration and time. So much about safe conditions; that is our approach; I recommend it to you as a very valuable method, or express ing this relationship. I now want to turn to discuss what we refer to, confers* ionally, as the two-disease hypothesis which Doc tor VorHsJLd has already raised with you# We find, in simple pneumoconiosis, we call it, these discreet capaci ties throughout the chest, and we find these massive lesions# Are the massive lesions just due to large quantity of dust in the lung or are tu.oy due to the action of some other agent and dust? Doctor Golfe*e view is that tnese lesions are tuberculous, as Doctor Vorwald said. Ke finds tubercle _______________________________ ___ ________ _____________ 226. I I I bacilla in fifty percent of them at poet mortem, but in | the other sixty percent he doesn't find them. He says that the histology looks to him like tuberculosis or the same. Doctor Vorwald won't support him there, and I can't enter into that, but we have got this large number of case* without definite overt evidence of tuberculosis at death. The explanation on the tuberculous hypothesis is that the tuberculosis has died out leaving its scar oehind it, but I don't like that very much, because we progress rapidly right up to d: ith, and that have progressed right up to death, do see cases that i even in those easesj i we have two in which we failod to find any definite evidence of tuberculosis. It Is possible that the tubercle bacillus initiates soma process which then becomes self-propagating. We know that the dust in the lung is mobile, even in these little foca, because a man with simple pneumoconiosis, when he gets bronchitis, will cough up dust in hi3 sputum many years after he leaves the mine, and it may be that once an in fection starts in the lung, the rest of the lung ends to move up in that focus and then starts a propagating pro-- j cess that is due to the dust. That is a possible way of : explaining these progressing lesions after tubercle has | I died cut. ' 1 But we still believe that there is a lot of evi dence for ne tuberculous process and certainly .for them ; 1 being two different disease processes involved and the evi dence we have, I want to just discuss with you now briefly# First, the Europeans say that these massive lesions are due to the action of silica. If so, we would -- sox-ry, will you Just skip the next four slides; t h e y 're just pictures that Doctor Vorwald has already covered on the patr ,logy. I think I can skip that, so come on to the next tables I just put this in in case Doctor Vorwald hadn't covered it# Here we cone to cases that Professor King in . London and Nugalschmidt have done analyses on, on the whole lung in relation to the pathological group, normal, slight simple, marked simple, early coalescant nodulation and naaaive fibrosis, and you will notice there is no difference in these groups in proportion to the amount of free silica anywhere in that table# If these massive lesions were duo to those oases with a lot of silica in them, than we ought to find a high- ar proportion of free silica in those massive cases, than in the aisiple cases and you will see nine, ten, eleven, so we d o n 't think that it's due to silica# How, evidence then,for their being two processes I in the progression of the disease# We have followed cases j over various periods of time, using other p e o p l e 's previous; X-rav3 in thi3 group, and our own X-rays here, and in simple 228. pneumoconiosis, with dust exposure, without dust exposure, and with dust exposure, we had eighty-one cases Category 1 to three without dust exposure. None progressed; two hundred sixty cases with dust exposure and eighteen percent progressed, so in smaller interval, our own X-rays, divid ing no dust exposure, minimal, engine drivers underground, and under oontrol code, none progressed without dust ex posure; 21. -- 2.1 with minimal and 7 percent with dust exposure over this short period. Those are published al ready, so that pneumoconiosis progresses as duch only with dust exposure. Now, you go on to massive fibrosis; there are two features, one the attack of massive fibrosis on simple pneumoconiosis, and secondly the progression of it once it starts. Here again, small groups of cases, on here, forty in each group, but with over five years dust exposure and no duet exposure. This represents the attach, the number of cases attached by massive fibrosis in that period, rather | more in the no dust exposure group than the dust exposure. There is not a significant difference. When you cone to progression again, no difference; significant difference in the amount of progression or the I attack rats of massive fibrosis in relation to dust expos- j tire, so in relation to dust exposure, the two types of ap- ; paaranca, radiological appearance, behave differently. | _________ ________________________...___________ 229. _ Wall, now, the way In which we've tried to fur ther our knowledge of this question is an Ingenious and courageous plan put forward by Doctor Cochran. We can't produce simple pneumoconiosis in animals and we don't think, therefore, we oan really get relevant information about the tuberculous nature of massive fibrosis from ani mal work. Well, than, he said we'll have to use men and he took a complete population of a mining valley, the Littl Rhondda, which is the Rhondda Fach, he took the complete population, thirty thousand and decided he would X-ray them all end he would then discover all the cases of tuber culosis in that valley, open tuberculosis, with the help of the regional hospital board, ha would get those cases into hospitals and have sputum control of the majority - the remainder, rather, and by one-two testing, see whether he could reduce the rate of tuberculous infection or infac tivity in that valley. Ee would then compare the attack its of massive fibrosis in that valley with that pertaining in a neighbor ing valley where no special measures had been taken. j This shows his success in X-raying that valley, j i I do want to pay tribute- to Doctor Cochran for this remark--i ~ j able performance. These are age groups along here, w omen j j here, men here, and this is the proportion of the total < population established by private census at the time of tho i 330 X-ray survey, and the ground is well over one hundred per cent* Where it gets over sixty, where it's difficult to get some of the old men and old women out, the survey was done in winter which is a mistake, because it's difficult to get them out and convince them their X-rays have any relevance to the health of the community, so you just com pare this with the business figures published in this country, where a careful census has been taken according to county, and considerably lower figures, and this inter esting dr p in the young, the men presumably too busy, and the women with too many children to be able to leave and come to the X-ray* But anyway, that remarkable achievement there, I think, shows that he has succeeded in getting nearly all the eases of tuberculosis, except some of these here, on X-ray# Well, now, the results of his experiment won't be available, of course, for five or ten years# But meanwhile, there are some interesting points from the prevalence point of view, which are relevant to our problem# This snows the numbers actually X-rayed, miners, ex-miners and non-miners, the adult females and the school children. The infants in the school areas ware not examined, twenty-one thousand more* j In the course of this survey, Doctor Cochran and j his team have - his team of four, in six months, they had j -- -- T no less than twenty-thousand personal hone visits to poor people in the valley# This rather depressing picture shows the preva lence of pneumoconiosis in the ex-miners and miners in the valley. It shows there is quite a lot of pneumoconiosis, study of simple pneumoconiosis here without fibrosis in which the study of the attack rate and also quit;- a lot of massive fibrosis to study too, enormous population there, and the toted, numbers in this whole -oup are about nine thousand. How, this is quits a complicated onjv I do apolo gise. The first point is that there is a logarithmic scale! and hsra I considered cases of infectious tuberculosis, let's say, with a positive smear on culture, cases of in active tuberculosis, diagnosed on the radiograph as held inactive tuberculosis, and cases diagnosed as clinically active tuberculosis, let's say, cases requiring supervision^ or in the cases where there is pneumoconiosis or massive fibrosis, and we found none in Category 1 in which the shadow looked like pneumoconiosis, but in r, nj cases, on the others, it was awfully difficult to call the thing tuberculosis or massive fibrosis, so we put them here. j j We have in category, infectious cases less than ' one percent, inactive tuberculosis ana clinically signifi- i cant cases. Coming into Category 1, there ._s practically no infectious tuberculosis, and indeed in a survey or theseL all these men and the neighboring valley, this one man is the only case out of four thousand miners in Category 1 pneumoconiosis, we had had a positive sputum on. There is decrease, insignificant decrease in the amount of clinically significant, but a rise in the prevalence of inactive# Might we suppose that a little bit of coal dust in the lung increases the fibrogenic action of tuberculosis so that there is a tendency for a healed active scar and a reduction in the tendency for open tuberculosis, might that explain the facta? We then get a bit more coal dust in the lung. Category 2# Fibrosis is further stimulated. Massive fibr-or is begins to appear. The inactive cases drop off as they're going slowly over there, but now infec tious cases begin to appear when we gat up to Category 3 when it goes right up to sixty percent. Thus., in the case of massive fibrosis, of course, the Category is read on the background and your - it means unreadable, where it's that you simply can't read cimple pneumoconiosis in the background . What's interesting is this reappearance of infectious cases and quite a portion or proportion of about one percent of the cases of massive i fibrosis do develop positive S'-utum so that even though they are ^finitely these highly fibrotic lesions on our tuber- i cular hypothesis, some of them may, for some reason or atheqr and it's aimoet entirely in the age group over forty-five, break down and develop active tuberculosis, spreading tu berculosis It*s perhaps of some Interest that it*s at that age that the mortality of tuberculosis rises in the general population. Perhaps its something to do with resistance. But, now, I can't speculate any further. Hexfc slide _ and I must just point to the future for what is going to happen in this valley. And this is a map of the valley as it was in the first of September, 1950, with all the positive cases marked by pins on the map here. There is all the cases, in or out of hospitals. This is the same date, with the cases who were in hospital removed, and I think that it expresses the inadequacy of our present tu berculosis services, that is the vary small impression that they make on the amount of infectious tuberculosis in a raining community, but the Regional Hospital Board said for this special purpose, they would open particular wards J to which these men could be admitted and that was the posi-j tion the 1st of October, 1951, the 31st of October, 1951, aj year after the survey started. This ~s relatively small, only about thirty-nine out of the original one hundred twenty-two are still in | the valley, four months later only thirty-eight. The others are still in hospital or in their graves and the remainder : 2_Ht here are being carefully visited every month by a health advisor to insure they are really looking after their sputum, not going out to tne pubs, and generally behaving themselves* And what will be fascinating in the future will be to see what effect this has on the none too positive rata in the children, and then what effect it may have on the attack rate in massive fibrosis in those who already have simple pneumoconiosis in that valley, when compared with the neighboring valley in which this special procedure has not been followed, and I hope perhaps at your next Symposium, Doctor Cochran may be able to come himself, Doc tor Vorwald, to tell you what he has found. Well, now, gentlemen, I have spoken chiefly, on - about methods, just - and there is just time to refer to j this chart. This is - I just nave this one. It's a vary J provisional chart, this is the first of one year, but it*s j the mortality in age groups during the first year after thei survey according to X-ray category and here is massive fi brosis, simple pneumoconiosis, Category 1 and 2, and that is the figure for the whole of England and Wales for the j year, j Simple pneumoconiosis is just lined up completely with the normal population, normal male population; massive fibrosis is up, but I don't want to lay too much emphasis j 235. on this. It*a only one year and this particular kick here, which looks so impressive was due to four cases dying and two of them had carcinoma of the lung, so I think there is very possibly a significant difference up there. But our point, I chiefly have spoksn to you about methods and I'm afraid I have given you very few answers. I have, I hope, perhaps convinced you that there is some subtle difference between, at any rate, Welch end - Welch anthracite and steam coal dust and English bituminous dust. No same safe level would be applicable to these two mines. I have touched on this two-disease hypothesis which we regard as very interesting and which we can not solve our problems at the moment, but we believe it to be perhaps more important than the problem of safe dust con ditions and of simple pneumoconiosis. Doctor Hugh-Jones will show you this afternoon that disability in this dis ease is very largely attributable to massive fibrosis. V/e have some preliminary evidence that mortality is related to massive fibrosis. If simple pneumoconiosis is really not i much more than an abnormal raciograph, then it's simple j pneumoconiosis, that's caused by dust and if it is true j that massive fibrosis is due to an additional factor, par- \ haps tuberculosis, maybe that we oughtn't to worry so much j about dust concentrations which cause the imple pneuno- j I coniosis, because the abnormal radiographs with little ' 236. disability and little mortality and what really we ought to do in our country is to remove tuberculous infection from the mining ideas and if from the mining area, why not from the rest of the country. I don't say that is necessarily the answer, but it's toe way we're thinking at the moment. I think that it's going to be exceedingly difficult to lower our dust concentrations in British coal mines, the level of which no man will develop the radiographic abnormalities of simple pneumoconiosis. It may not be necessary to exert that close I - that collossal an effort with all its economic consequences: i if we can protect the population from tuberculous infection* but first we*ve got to prove our point. (ApplRuse). 3Y DOCTOR P R I M E R : Anyone wish to question Doctor Fletcher? BY HR. URBAN; I wonder if Doctor Abbott would like to comment J - Doctor Hammond, would ha like to comment on what he did j alongthis line in Michigan? j BY DOCTOR DRINKER: ; I couldn't hear that. j DY KR. UB3AY: ^ ^^ j Is Doctor Hammond here? ` W W M J1W S^ Well, I haven't been in contact with the iron nl,,es for a long time, Doctor Urban. and I don't know that I have anything to add to what Doctor Fletcher aald In that llo,, but I think It'a - hia experience parallels our own pretty well. As 1 llatened to him, I thougnt that w. war, getting right back tc wnat we her. In Saranac Dak. were taught a good many years ago -- when I say a O ood nnnj year. ago. I mean ten or fifteen - that tuberculoei. waa the important thing, path.?. In thea. casaive " tootle 1ealons. Uo felt up there that every shadow w. aaw In an x-ray at that tin... in our own bailiwick there, would prob-j ably have to be interpreted in the light of being tuber- c^juLovts Now, I think that we're probably getting away from that a little bit, but I a till think that it is par- bape the Important factor, and I know that up there, . vary definitely felt that if we could protect thea. people free | tuberculosis, then we had a much better chance of getting | disability from silicosis in that field. We bad a situ.- tion there which war perhaps somewhat union. In this conn- ; t,, as far a. the problems of prevalence of tuber-ulosi. | uere concerned. W. had some family histories that were. j well, to say the least, they -ere unusual, b u t by Inter- , , ,oun-- people become diseased with tuberculosis,; marris.ce f t-0 r > p a r e n t s a r e it uh aann - D i n eb i n t o t h e n i n e s a n d c o n t r a c t i n g tuberculosis at an early date, sonetimes dying with chair boots on. Those days now seem to have disappeared pretty well since we have better methods of exhaust ventilation in the mines, but those of us who worked in that area, and there are a number here, I think were pretty well convinced that in the majority of cases if we could control that# we could prevent disability from these cases. BY DOCTOR MOTLEY i I*d like to ask Doctor Fletcher, if in the epi demiological study they have made, any correlation with the study of the man? We have occasions to study buddies who were in the war together, in some cases even brothers# and one man may become severely disabled, where one man may show only slight disability# The factors we have thought of is sinus infection, mouth breathing. I know Doctor Schepper, when he visited my laboratory from South Africa, made much of the physical examination they gave the white i-,n there before they permitted them to work in the gold mines. tion and in They gave them a very rigid physical examina correlating dust count, it seems to me there J might be soma co relation with the rapidity with which they! develop changes, and it*s a physical finding and I wondered! * j if they had made any attempt to correlate that. j BY DOCTOR FL Y !' One man being taken and the other left t's like the Bible call, the last Judgment. We have got that too; one has massive fibrosis and the other hasn't. Two men work the same place, one man gets a huge mass of shadow and the other doesn't, one is disabled and the other isn't. You could say one has tuberculosis and the other hasn't. Whether in two men exposed to the same dust conditions, one will develop radiological abnormality and the other will not is a problem we c.-scuas at great length. We have, at the moment, got a group of miners who have worked on dusty coal faces for more than twenty- five years, in whom we can find no radiological abnormality, we hope to trace those up to see what happened and we hope j to chase them into Professor Goffe's department to see if our X-ray is wrong or whether they can cope with disease so efficiently they don't take it, and I personally believe that some men have such competent phagocytes or some thing of that sort that they cope with dust that many others will be susceptible to. Ky colleague works with animals, and he says that one will be exposed to dust and will cope with Jtx and the others may be susceptible, and he says that animals and men are the same in regard to c.-st. Ho may be wrong and I 'm not. In regard to South African experience, examina- J tion, p ophylactics, Dor-tor uoehran has done a great deal I or investigation as to radiological activity and body type. By evidence, he has been able to sort his men into tall, thin, short, squat, and so forth, and there is no relation at all between these anthropological measurements and pneumoconiosis, simple pneumoconiosis; on the other hand, there is a relation between tho tall-thin type and massive fibrosis. Either the tall, thin type are more prevalent to get massive fibrosis and tuberculosis, or when a man gets massive fibrosis and tuberculosis, he becomes thin tad tall# ; BY DOCTOR DRINKERt Doctor Sander? BY DOCTOR SAMPERi ' I*d like to ask, do you have a correlation, or have you made a correlation with emphysema in tha various categories of simple pneumoconiosis, clinically significant; emphysema, radiologically and by lung function studies? BY DOCTOR FLETCHER: As far as lung function studios are concerned, i 1*11 leave that to Doctor Kugh-Jones. As far as radlologi-; cal emphysema, I*m afraid vq *vq been so far disappointed J to read emphysema repeatedly on X-rays, that we have dacid-; ed that a radiological reading of empnysema is worth about j as much as the ink, the Lur: you bother to write it down | with. But we do know our radiological categ'. ios are i 2kl, unrelated to professor Goffe's focal emphysema. All we can say In the very advanced focal emphysema, Professor Goffe has go: two or three cases, one of which published in his paper in the Faculty Radiologist, where there is gross focal emphysema, and the radiograph does show a kind of honey-comb pattern, ao when we see a marked honey-comb pattern in a miner, we think perhaps he has got focal emphysema, and we have got about three X-rays of that kind, and the man has either died or we haven't got them. So I don't thi.k I can say that; all I can say is where massive fibrosis develops in the last stage, there you can sea the big bully and you can be pretty confident# BY DOCTOR SANDER: Did you feej. that your first film on the left. Category 1 has emphysema? BY DOCTOR FLETCHER> I feel it has, but I'm not sure. I'm not defi nitely positive. BY DOCTOR SAKDSR: You feel, logically, there is emphysema* BY DOCTOR F.7BTC HER : I feel there is, but if you haven't done any careful repeat reading of X-rays to classify them as emphy sema and correlate them with th3 physiological findings, but I would only say that where the emphysema is gross, and. I think that one of the3 films fell into that type or category, then I would he jolly cross with the physiolo gist if he didn't find some evidence* BY DOCTOR HATER I Now, ue can discard completely the term antiiracosilicosia here, and to consider this as a form of anthraeosis with infection. If so, it's going to effect our atti tude toward compensation because our laws in New York State compensate the silicotic. Now, would you have us discard that term anthraco-silicosisf BY DOCTOR FLBTCH5R: Weil, if it's going to deprive coal minors of compensation, I would say you must go on calling It sillcosis, but I hope you *11 be putting invar tod c o m a s on each side of the word, because I Just don't think thora is any evidence that the very small silica content, you nay have noticed how very small the silica content of this ccai dust is, I don't think there is any evidence that thiB silica content is responsible for this silicosis, even when Doctor Vorwald points to the diagram and says, hare us have the characteristic response to silica, in the middle of the thing. Well, I am reminded that Doctor Babbles con main tains that reaction to coal dust, with age, collagen may develop and it's common for any scar, so I'm told By trie pathologists, for collagen to develop, and it may be a I 2k3. reaction to aging as much as a reaction to silica, and I just sirrly say that the antnraco-silicosls implies to me that this Is caused by silica, and I don't know anything in the world literature to support that hypothesis. BY DOCTOR HcCORKICK: I would like to ask Doctor Fletcher whether he would care to comment about the range of dust concentra tions that you may find in Britiah mines, and where he has been able to set up any sort of d8fon: 3 marks below which his early pneumoconiosis does not occur* BY DOCTOR FLBTCHSRx The range is vary great indeed, and due to a var iety of reasons, the anthracite mines that have been very dusty In the past for various reasons* First of all, in anthracite mines, there is no danger of coal dut t explosions Therefore, ventilation Is not quite such an urgent safety measure, and in general, anthracite mines have been char acteristically, have had sluggish ventilation in the past* There is much more short-firing anthracite mines and they have been very dusty. B.itumlnous mines : ave to be very vigorously ventilated because of the danger of coal gas and coal dust explosions, and by and large, the dust production! from the tibuainous coal doesn't seem to be so great* At the moment, in Great Britain, there is an official standard of 650 particles for anthracite, 850 At particles par cubic millimeter as approved conditions. Nobody states how long those approved conditions have got to be prevailing. That is to say, if a coal face is ap proved, if the dust concentrations rise for five minutes a^ove that level or the average for a week or what, V* feel that the right figure is the average for a month, and Doctor Righter is busy designing, has already designed a dust sampling instrument which will give an integrated sample for a period of a week and just give you one dust count to do at the and of a period of a week and we think that will be a sound basis, Werl, now, on those figures I pointed to you on the board, men will develop simple pneumoconiosis under those approved conditions. There is no doubt about t. At, i so that the level will have to be lower if our objective isj going to be to provent all radiological abnormality, but massive fibrosis doesn't develop until a man has got at least category 2 in our experience, so that perhaps that's the level we ougat to aim at, and we may not have to drop this too low to achieve that. Certainly in bituminous mines, we may have to bo more strict thar. anthracite and steam coal mines, j There is one other point, I showed you a fall j in the a m o u n t of infectious tuberculosis and clinically sig1nificant tuberculosis with a rise in inactive tuberculosis In category 1. Maybe we ought to give all over coal miners clinically active pneumoconiosis to protect them from tu berculosis. It Is interesting that mortality figures for Great Britain, and I think other countries too. Great Britain quite definitely, have snown a low tuberculous mor tality for coal miners* Now, in Great Britain as a whole, Category 1 ij!! j! pneumoconiosis is very prevalent and there is very little |; 2 or 3* Maybe that is a - its an advantage to a coal i miner to have just a little dust in design, enough to proj tect him from tubarculosis, but not enough to disable him* j BY DOCTOR WARING: Id like to ask Doctor Fletcher if he has made any studies of the conversion of the tuberculous ties In | relation to the development of pulmonary - progressive | pulmonary fibrosis, massive fibrosis? j BY DOCTOR FLB^CHBR: j Unfortunately, we can*t do that, because our mln-j j! j !; rs have such a high disability rata. At the age of fcurtD^n, i! I i! when leaving school In Rhondda Valley where we haa this j ;; j } figure, I think its sixty percent mine coal, but the earli- j; est, at the age of eighteen, which is the earliest we gob ;! a mining population, it's ninety--five parceat, 30 o-n* cnanc^ I of watching that are very slight. We hav- got two miners j in Cate :ry 2 pneumoconiosis, positive, and wo"re watching j 2!t6*_ them like anything, but unfortunately, one got nephritis and died so we have only got one, but in the future in Rhondda Valley, we shall have opportunities for that sort of thing* BY DOCTOR FRIEDMAN t Id like to comment on Doctor Fletchers remark that we could detect some of the difference In the body in the people who have conglomerate lesions In the X-ray and the physical appearance* W e 1re studying about two thousand soft coal miners in Alabama; we lave failed to establish any correlation betwoen body buiii d and the appearance, whether it be a simple type of pneumoconiosis or whether it should be a fibrotic variety* However, we have observed that where there is a coalescent factor and the inf ion becomes overwhelming, in the event he dies in a state of malnutrition, it becomes evident* Kuw, the second point Doctor McCormick raised about the dust levels. I feel, and I think it is true too, that regardless of the safe level of dust in which a man works -- and that is within reasonable limits of safety -- if he works long enough in that environment, he will obtd.n the same type of exposure, let's say, in twenty years in a safa environasnt that a man would obtain in an unsafe en vironment, in a lesser period of time. I don't tnink we smould place too much emphasis 247a over the long range period of time on safe levels of dust, because of the individual exposed long enough toa dust, he will get the same effects over a long period of time which he canin a short period of time in higher concentration. EY DOCTOR BRODKIN: My name is Brodkin and I was going to ask a sirapl question. The incidence of scars is frequent enough. Has anyone made any correlation between the tendency to keloid formation and the extent of fibrosis? You take two Individuals. Each has the same scar over an area; one will develop -- irrespective of any infectious bacteria, one will develop a large haloid, the other one will develop a fine hair-line scar. Has there been any correlation of thatt BY DOCTOR VOHvJALDt Who is he asking that of? BY D-JTOR DRINKER: Were you asking that of anyone in particular? BY DOCTOR BRODKIN: Well, anyone. BY DOCTOR VOHHALDS I have no evidence - I have no evidence to show that, for example, individuals or subjects from the faces who develop keloids very readily, that they respond more readily to the deposition of dust in the lungs with the j 2^8. formation of collagen. I have no evidence, but we do know of course, that collagen does form in the Negroid race and I the Caucasian, people from Japan and elsewhere. Perhaps Doctor Orenstein could tell us somethin g about that. Doc tor Orenstein, Doctor Orenstein, can you comment upon whetner there is, in the Bantu, the colored individual, presumably a greater tendency to dovelop keloids, and if so whether he is more prone to dovelop collagen in the lung due to the deposition of dust, than is one from a race without or not prone to develop keloids, BY BOCTOR ORENSTEIN: j Why, actually, it used to be one of the extra ordinary museum specimens that we had and still have, of our Bantu lungs and spleens and livers with enormous thinga that you used to call tuberculoma, huge daposits, and nowa days you don't see it any more. The specimens are old, I don't know why, I have no explanation. It would be pur poseless to detain you here with trying to explain differ ences between what you see in colliery workers in, say, Wales, to what you see in the workers in Johannesburg, where they work in a high percentage of silica, and his- J torically, it's a very complicated thir.r, so I don't think vou want to take up your time, because 1 can only say this, in the Bantu and in the white nan, the type of pneumocon iosis which is so in the first two and a half decades of | 2h9 this century and the type you have today are as differnet as anything can possibly be, pathologically, microscopically and clinically. BY DOCTOR VCRWALDs Certainly wo know from evidence there 1b a c'"eoie$ difference, as for example, the white rat is much mors j prone to develop collagen in a snorter period of tine than is the guinea pig or the rabbit, to the pulmonary deposi tion offroe crystalline silica, but again, I certainly have no evidence that the colored race responds with more colla- i gen under the same conditions of exposure than does an in- J dividual from the white race. j I Now, perhaps Doctor Fletcher would like to cessment* Fletch, Charles, do you want to say anything about that? BY DOCTOR FLETCHER: I have nothing to say about that; I would hate to be charged with designing experiments on this problem. BY DOCTOR AENEHt Abner, Buffalo, Hew York* Isn't, logically, a keloid the same as a fibrous tissue appearing in the lung following silica and if it is, should the response to y- -rav" therau~ v* b9 the same* ij BY DOCTOR VO?-1*'A L P S ' Well, histologically, the actual architecture of , I the keloid, histological architecture is different than the. ! I --_______ _____________ ___________________ 250. architecture we see in the silicotic nodule, but basically it3 collagen and I assume formed in a different way* I can't comment as to whether the collagen in the lung would be as amenable to change under the influences of X-ray therapy as might be the keloid* BY DOCTOR DRINKER: SI ! All right. Doctor Friedman* II BY DOCTOR FRIEDMAN: j Half of our population in the coal mines in Ala Si bama is colored and the other half is white* We have not i been able to detect any difference at the autopsy table or i in the Roentgenogram on both* Now, on the other hand, we i f have an opportunity to examine one Kc t o who had massive i It\ keloids, but his bon specimen didn't show any inflection i of what his skin showed in keloid formation* There was absolutely no correlation that we could detect in cur p study. You can find just as much fibrous tissue in the white man as you can in the colored man and I say, as Doctor Vorwald pointed out, there may be more of s*n indi vidual difference than thex'e is a difference between the races. We can't detect any racial different in response to the dust* However, only one thing, we should Sf" in con ditioning this statement, is the fact that the colored population in our community live in a little less pheasant j il environment* They don't have quite the economic facility that some of the white people have and the mortality rate j in our colored miners that work underground is greater* BY DOCTOR B03TJER; I wanted to ask Doctor Fletcher if there is any difference in the prevalence rate in the general community in the English mining area which you were showing us, com pared with the Welch mining area? BY DOCTOR FLETCHER; There is an interesting point there* The male population, mortality rate, is very specific, White Haven Borough Council and the Rhondda Urban District Council, here is distinct lines of pneumoconiosis, hsie female r&fcos are almost identical and the children mortality rates aro j almost identical, but it is interesting that the male aor- j t&llty rate in the Rhondda shows a deficiency, particularly j in the age groups. How, if you add in to the age mortality, the male pneumoconiosis mortality which is nearly all pnermoconiosiai massive fibrosis, then there is another argument here fcr supposing that the men dying here of massive fibrosis would have died of tuberculosis if they hadn't had their massive fibrosis. --v-y--DO-C-T-O-R- BSINKER8 i Can you people in the back of the room hear this? | 252. Can you hear the speakers all right, because I nust say I can't hear when they ask me, but it may be a reflection on me. Can you hear the papers all right, you in the back of the room? (General response indicating HYesM ) BY DOCTOR MILLER t I wish Doctor Vorwald would comment on the idea that concentration of exposure w e s more important, the dur ation of exposure was more important than the concentration!. BY DOG TOR FLETCHERt Excuse me, the other way around# BY DOCTOR HILLER: No, I believe Doctor Friedman said that the dur ation of exposure to a noxious dust was more important than the concentration, maybe I misunderstood# EY DOCTOR FRIEDMANS I said that the duration of exposure has to be taken into consideration, it was also a very important factor# BY DOCTOR MILLER: Oh, not the sole factor? EY DOC "OB F B TBDMt..:s No, sir# BY DOCTOR FL ET C H ER ; I might jus' answer that point. i The evidence we 253. have got on that point is simply this, that if you - If you do your time, your response curve here, the miners who have been exposed to more than a thousand particles per c. c. and less than a thousand particles per c. c , we have got time along here and percentage effected here, then the people in the high - that's concentration - show a durve like that; the people in the lower dust concentration a curve like that, so that just for equivalent particle years, you have a smaller response if the actual concentration of dust was level, and that is purely provisional, and is J j not of statistical significance there, but it is a trend J that makes us doubt the applicability of our figures, necessarily, to the whole range of concentrations, BY DOCTOR VOHl<?AhD: I should like to make one consnent end that is with respect to the free crystalline silica content of the lungs. Doctor Fletcher pointed that out and he us*d the low free crystalline silica content of the lung as a basis j for saying that probably free crystalline silica is not a j factor in the reaction of the lung to the deposits of coal ; dust, C orrect, Doctor Fletcher? b v nonTOR FLBTCHgR: ' No, there is no more free silica in massive fi- ' brosis than simple, so the massive fibrosis isn't due to m ore silica in the lungs in the fibrosis cases t'-n in 22fc. simple pneumoconiosis. . BY DOCTOR VORWALDt Well, some of our experience would be different than that, in that we have analyzed some of the massive fibrosis lesions and some without, and we have found higher free crystalline silica substance in the higher massive fibrosis lesions. I might emphasize though that there are those where we have not found that. I would like to say also, with regard to the frae; j crystalline silica in the lung, we have examined many lungs j of normal individuals,9 of individuals who have been exposed;1 I to free crystalline :lica, but without silicosis, and of J individuals exposed to free crystalline silica with silico sis. Now, there is a wide range of values observed in the normal lung versus the lungs of subjects without sill !} cosis, but exposed to froe cry.* -oalline silica, and the j ^ i lungs of subjects with manifest silicosis. There is a wide; range, and this range overlaps, so that except for the ex- j i treraes, the two extremes, we believe that there i3 relative ly little value or one can give a little index to tha amouns c free crystalline silica in the lung as related to the j degree or character end extent of pathology within the lung. There is no correlation. , 1 EY DOCTCY GR5SN5URG; ! __________________________________ -_________________ 25 *._ How about the time factor. Doctor Vorwald, did you taka that into account? BY DOCTOR VOHWAID t Well, I can't specifically give those figures; it's over a long period of tine* In other words, here are fifteen normal lungs which we analyzed and they ail have free crystalline silica, a certain range from a low to - I forget what it was - twelve percent, Mr. Durkan, do you remember those values? m HR. DUP-Il&S: Ho. BY DOCTOR VORWALD: Then we have sixty or seventy-five lungs of in dividuals who have been exposed to silica by reason of their employment, yet without silicosis pathologically, and they have a range of free crystalline silica value which is bread that wsy * Then wo have forty-five or iifty sillcotics, es tablished 8ilico3i3 of Industrial workers, and they do have! i a large range, but this range overlaps so that except for | i the extremes, we can not place any correlation between the j amount of free crystalline silica detected in the lung by j our methods and the degree and character, extent of path- I | ology, silicotic fibrosis in the lung* j BY DOCTOR GRSEH3URG: : >nf oftn boo, W " '1' th" 18 m thV W`y r what Haa , persona s u s c a n H K n ^ , e or av ^ lB lndl'la"l variation toot BY DOCTOR VfiPWAT n . T th a t. Yes, but maybe Doctor Prat-*- ^ P r a tt w ish es ^ comment on BY DOCTOR P n i w . 1 think there la one important thing more that should be added to that Z Z Z & ' p r - was k . ,, content, tnat is that all that work was based on the percent of aiilca ln , , *>* - t or .illca la " 1UBe' W Wva<.tthh tiie amount of silictf^1tn , s a"h 0OTTM i t r5 t* uolna a , lune' but using a simple technique to d e t a i n recant!, In the ^ th amount of silica in the lung, that correlates a great dee! k great deal better with tbe amount in animals asirf , ,, . M U9 nice correlate ^ ** f animai oxPoriments show ^ n * bUt thS amount r disease estimated in SeCtl0nS " ^ ^ <* * ^ c a i,, ^ To quote one example or a case m whlch lung showed fibrosis, another lung showed slrapla Rod , * . sirapia nodular sill. 1 * Xn eacn IwiS the percentage of ,li_ ' but on the basis of total araount Qf ^ ^ ** " " f no gi.m la luEg shoulag ,, brMlj> evon percentage was the same. ' i j .... Obvioosl,, tho dlfrorer.be is ^ ^ ^ ^ ' 232a reaction dilutes the silica which is present, and I think Doctor Fletcher*a figures could be a lot more convincing if they were based on the total amount of silica# BY DOCTOR DRINKER: ' I suggest we better adjourn and continue the discussion this afternoon. this afternoon* The next meeting is at 2:30 -oOo(Adjournment taken from 1:10 to 2:35 P. M , ) [ ! PNEUMOCONIOSIS Ilf COAL KHJERS (Continued) 2:30 to 5:30 .PHj Chairman: O* A* Sander, M* D# Sept*23f 1 Pneumoconiosis in Coal Miners in Alabama Louis Friedman, K* D*. Discussion Pulmonary Function Studies of Coal Miners in Pennsylvania and Vest Virginia Hurley L. Motley, M. D* Pulmonary Function Studies of Coal Miners in V&JL33 Philip Hugh-Jones, M, D* Dis cussion B Y DOCTOR SAhDSR: .Let 's have the meeting come to order, ..a'll carry