Document 6bXb9QY0eo9NGm5gKLZaNBqRg

Urn J. imimtr. \M.. 1*71. M, 211-216. PLAINTIFF'S EXHIBIT DOW-1420 insulation workers in Belfast1.1. Comparison of a random sample with a control population WILLIAM F. M. WALLACE and JEAN H. M. LANGLANDS Department of Phywotogy, Madicd Biology Contra, Lisburn Road, Belfast and Respiratory Investigation Unit BeNaat City Hospital, Lisburn Road, Belfast 7W 17-17* k 2- > < WaiMS, W. r. M. Mri LaedtaMb, J. H. M. (I97IL Bril. /. ImJusir. Mtd., 2t, 211-216. IsmMm setters is Mhet 1. CMVartae f s rasSasi Maple wfck s cartrot population. A sample of 50 man was chosen at random from the population of asbestos insulators in Betfaal and matched with a control series of men of similar occupational group with respect jo apa, heipht, and smoking habit. HpnMcantly men of the insulators eomptained of cough and sputum itnJ hud haw! rules on rumination. Cubbing was assessed by means of measurements of the hyponychiu! angle of both index fingers. These angles were significantly greater in the group of insulators. Twenty-one insulators had x-rays which showed pleural calcification with or without pulmonary fibrosis; one control x-ray showed pulmonary fibrosis. The insulators had no evidence of airways obstruction but static lung volume was reduced and their arterial oxygen tension was lower than that of (he controls and their alveolar-arterial oxygen gradient was greaser. There is a considerable body of evidence that exposure to asbestos may lead to symptoms and signs of lung disease (Mere#ether, I93J-4; Wyerx, IW; Williams and Hugh-Jones. 1960b; Leathart. I960; Bader, Bader, Tierstcin, and SdikofT, (965; Hunt, 1965; Thomson, Felrtr, and Smithcr, '965). However, other factors to which asbestos vorkers are exposed - cigarette smoking and atmospheric pollution - have been shown to play an 'mportant pan in impairing lung function. Fo' example, lletcher. Elmes, Fairbaim, and Vood (1959) surveyed London postmen and fot'.id that about one-third of them eomptained rT mild exertional dyspnoea and between one-third and one-half gave j history of cough and sputum for at least three months m the year. Thus it is likely that some o( the disability found in asbestos workers is unrelated to exposure to asbestos. 'Thu mvrMigUKxi * cimed oul id (hr Department of Thmpcvtict. Imuituie of Clmtetl Sctmcr. Crtmrenof Road. Belfast 12. In order to avoid overestimating the harmful effects of asbestos, comparison with a control population is desirable and the controls should be matched as far as possible with the asbestos workers, not only for such factors as age and height, but also for environment and smoking habit. The use only of controls who denied all respiratory symptoms would be quite unsatisfactory. In the present survey wo have investigated in detail 50 men selected at random a population of insulation workers and have compared them with a control series who were closely matched for age. height, smoking habits, and general occupational group but who had minimal exposure to asbestos. Method* SoiacUoa ef workers The names and addreMcs of all men working as insulators in Northern Ireland were obtained from their union (membership of which is a condition for employment). The names were arranged alphabetically and numbered. <S) O O KO C/1 212 WUktm F. M. Wathrt tmlJnm H. M. Umkmh tn PO Mactkm wa mads wing random number laMex. Mm In TaMt 9. Because not all tha control x-nyx wm who lived outside i redlw of about 20 milt* from the IUWn film*, no attempt wat mada to use tha I.L.O. centre of Bethel em excluded. Tht home of mch mm selected wm visited end m appointment emnped, Thom who MM lo tttmd wm revisited tnd a further affort chmdficailon which wm utad in examining tha x-rev* of the aiHlr* group of Insulation workers (Langtands, Wallaca, and Mmpaon, 1971). wm mada lo ancounaa attendance. In order to examine Tha uw of the 100mm fllme wm not ideal but It wm JO inaulctorv 3.' mm wm talaciad. Of Iha ihraa who felt that to taka a further chett x-ciy of mm who had wm Mlactad but not esamlnad, ona had suffered iam recently had an x-ry which wat considered normal chest Injury due lo a Ml et work and two refined to could not baJuMiOatl. atiand. Thus tha JO mm aumlnad raiumantad *4". of thou talaciad. Biaplralary hawtlau MaM Forced caplratory volume In ona aacond (FKVM) and farced vital capacity fFVO wm recorded on a Foulton tiaensler-lype spirometer Firstly, tha nama* of severel mm whose data of birth wm within a year f thtti of iha Imulalor to ha malchad wm obulnad from Hut of Hatftu Corporation em ployees. Thaaa mm wm thm Interviewed In turn until ona wm found who malchad tha Imulalor In hat|ht to within Jin <7-6 cm) and In amoklng haMt fMadlcal Research Council, I WO). Tha mm Mlactad wm thm asked If they would taka part In Iha turvay, tha purpose of which wm explained to them; only two refused and had to ha nptoud. Forty-one of Iha eontroh worked In iha local tranaport mainlananoa dapanmmt, ala In iha ana dapartmam (not In tha fat worfca Itaalf), ona wm a plumher, and two wm Hudant laboratory tachaidana. It wm Wt that them mm had a vary similar workini and Uvlna environment to tha Intuition apart from etpoaure to athrum. (MtiKerrow, McDermott, and Qllson, IWO). Peak flow rata (PF'PO wm measured on a Wright peak flow mater (Wright and McKerrow, 1959), In thaw tests, (ha mean of the lau three of five attempts was recorded. Arterial oxygen and carbon dioxide tensions (Poj and Pro,) and pH ware estimated by Astrun appnratus on Mood ohtainad by puncture of the warmed ear lobe (Langlandt end Wallace, IWJ). Expired elr was collected In a Thsot spirometer over a period of 2 minutes after washout and was analysed for oxygen wing a Servomex oxygen anaiyxar arid for carbon dioxide using a modified Haldane appamiue (Campbell, 19601. Alveolar Po, wax calculated using the formula given by Comroe and hht colleagues (1962) at page J3J, tubuHuilng oxygen fur carbon dioxide, m they suggest. Subdivisions of total lung capacity and transfer facton (Tl) for carbon monoxide In air and in oxygen wm measured wing the equipment described by Meade Tha following invattlaailont wm undartakm: and hie colleagues (1965). From the results, the diffusing capacity of tha pulmonary membrane (Dm) and pul* I Watary aad rtlalial waatlaatiia Tht Madleal Raatarch monary capillary Mood volume (Vc) wm calculated by Council lant nspintory queetlonnain (I WO) wm utad. computer, using formulae given by Cotes (1965). Single Rhonchl and ralti wm sought and nles, If prctmi. wm breath alveolar volume was used lo calculate Tl. The graded 1 if confined to the axilla, and 2 if present die* tranafer constant for permoaMllty coefficient) Kl was where. Blood pressure wat meatured and the heart oMaincd by dividing Tl by the single breath alveolar inculcated. volume. ----------- Impresslont were madcof thtdisuloncanda half phalanges of the two index fingers of each man and, from these, casts of tha digits were made. Clubbing was asaeieed by measuring the hyponychfal angle on each cast. The methods wad wm those described by Regan, Tagg, and Thomson (1967). An early morning specimen of sputum was examined for asbestos bodice by counting under - 240 magnificat)on the number of bodies in an area of I cm1 In two specimens, one unstained and one stained with methyl green and pyroninc to show the crflular content. The sputum ms positive for asbestos bodies If one or more definite bodies were seen In either specimen. ------1 x-ray A postcro-amerior film eras taken In full inspiration. It was Immediately checked for quality by radiologist and, if necessary, repealed. Control subjects who had been x-rayed (muse radiography) in the previous sis months did not have a further x-ray. In this way there wm Jl tothnm films and 19 standard chest x-rays for the 50 contrail. FHrm wm read by two experts In chest x-rays and classified under the headings given Rndti Exgcoare to edieefne The duration of exposure lo asbestos of the in sulators varied from 4 to 4t yean (mean S.D. 161 7 S yean). Details are given in Table I. Of the control subjects, 12 said they occasionally cut asbestos sheeting at their work and one had previously worked as an Insulator for three yean. TABLE I Exposure or Insulation Workers to Axaciruii Ytnrt of rxpoiorr 0-9 10-19 20-29 *>.w 40-49 Total No, of mm 5 32 tl 1 1 50 Adaq Meat with amok xubjo taller aimilb heigh contr< advar Ptm Meaa I Mtaas Naa sn Fx-emo Smoker 0-U, Smoker (15-2Smoker (25+ Thm i control sputum for cou dyspno of irtsu' sympto. in the i Twice a of eithe culosix t level (P wax me and in < different CkdM Measure index fir for omit the suhjt base of made ar torted. 4'gi . r. ' et< .' it-. * t o. 1 PV I.K 1JS* 1 N . t i..,-i..ndv .' k ' n-i' <1 mix n who haj kk'.'.l tti.tmy) `.M.iit.fv volume , SMMUtt (f VO "XI 7V Kl *,< bih ilvtolj ImuwoJiom workers in Brljust 2)3 Mon differences between insulators and corurotx wnh reaped in apt, height. turface area. and smoking habit an shown in Table 2. The cnotroi subjects wen on average 04 year* older and 2 cm taller than the insulator*. Smoking habit* were umilar. From prediction formulae baud on ape and height for lung function lasts (Cotei. IMS) the controls would be expected to have a flight advantage in tceti related to lung volume. TABLE 2 Physical CNaaacniumca and Smohino Hauts Mean see lyr) Meaa heigM (cm) Mean sums* ire* (in') NMiMkifl Ex ewehers Imeheri - gnds 1 0-U rip./4ay Metw-pMel <13-24 gtgsMay) ImcSars - grade 3 <2Si e**-/der 3P-4 tee in i) * f 13 10 ChpiS tHjeeeact 3*1 tTI IN II 12 -0-4 -2 -OO.l 2 -3 -1 12 1 41 TABLE 3 Symptom* *vd Skins os Cheat DtvfAxr Clunealfeature lm**latoe\ Cuafruh P1 D^fmooi* mild (grade 2) mofv Mrvcrc l grades ,'S> combined 16 13 1 71 2* 16 0-10- P>0 03 Cough" - grade 1 grade 2 combined 9 to 2* 8 yy 14 -.04)1 Spulum* - ;ade 1 grede 2 combined i.i IV 24 to 37 2> -0-01 Previous chest ill- bronchitis pneumonia pleurisy tuberculosis last three combined Rekis grade 1 grade 2 combined 13 7 K i 16 it l 12 3 J 0 * 0-20>?> 0-10 * 0 1 -0'02 Thau are shown In Table 1. More ineulaton than control* complained of dyspnoea, cough, and sputum; the difference was statistically significant for cough and sputum (P < 0*01) and almost so for dyipnoee (P < (HO). In addition, the proportion of insulators with more than the mildest grade of symptoms was much higher. There was no difference in the incidence or previous attacks of bronchitis. Twice as many insulators as controls gave a history of either previous pneumonia or pleurisy or tuber culosis but the difference did not reach a significant level (P < 0-20). In the case of rales the difference was marked; they were noted in nine insulators and in only one control (P < 002). There was no difference in the incidence of rhonchi. Rhonchi A2 ` 'P wsi obtained by using Btllewicz (196*) paired test. The grading is that recommended m the Instructions for the uw of the Medical Research Council questionnaire (1960). asbestos bodies were teen in nine cases. No asbestos bodies were seen in 27 control sputa examined. Radiological findings These ara summarized ir. Table 5. Only one control TABLE 4 Dabbing Measurements of the hyponychiaJ angle of both index fingers are summarized in Table 4. The reason for omitting measurement on some digits was that the subject pressed the end of his finger against the bau of the container in which the impression was made and the subsequent cast was therefore dis torted. The insulators had a significantly pester angle in both left and right index fingers, indicating a shift from the normal towards the dubbed range. Hyponychial Ancles or Insulators and Controls Compared Left index finger / P Right index iSnger / hxulatuen (Jefrees) Controls {Jeffers) into : 1-263 in-: jlO-sm 2-885 <04)1 :u 6 1 1-260 IM-4 j I-C6I 2-6.13 -*04)2 Lift into finjer 44 pair*; right mJcx Angrr 45 pjm; mc*nt Sputum from 42 insulaton was examined and r rtandurd error*. ST0095353 214 WiUiem F. M. WtUact md Jem H. M. iMXgtamh TABLE 5 Ramolooicm. FINIMNC4 X-eay gmdt ) Normal 2 ftmiMy ihoormal 3 Pleural cakifcatien only 4 Abnormal - 7 early aabniaeia 5 `Fibrow' - T atypical Btbntoim A Attotom Total IWilOlfl Cmmh 12 17 3j 7T t0 a0 51 90 so 50 Combtaing grades 3 lo 4, P 0-001 (Billewici d444) paired jr*al). Papuan toma of the control x-rays vert 100mm Alms, the I.L.O. rlasaiBnlioo was not used. had definite abnormality. His x-ray suggested the presence of diffuse flbroari not typical of asbestosis. He pve no history of exposure to asbestos or other dims and no explanation for the abnormal .r-ray was found. In marked contrast, 21 of the 50 insulators had definitely abnormal x-rays. Of these, 14 showed definite x-ray evidence of fibrosis and one showed pleural calcification only. The fact that 31 of the 50 control x-rays were 100mm Aims could have biased the comparison since these films were clearly from a supposedly norma, population. It is, however, felt that any bias from this source couid account for only a very small part of the marked difference ,, ..-tween the two groups in the incidence of ca.fi.Tiic abnormal.!-/ recorded jointly by :wo experienced observers of chest x-rays. lumg fmciiut tests A comparison of the mean results for controls and 'f* insulators is given in Table 6. The predicted dif- "H fercnocs shown are calculated from formulae given O by Cotes 11965), apart from the K.i (.V.cGrath and O Thomson, 1959) and Dm _.'.d Vc (Hamer, 1962). in the tests of static lung volumes the insulators fjj had smaller volumes than the controls in all cases, q For residual volume (ivV) and total lung capacity - -- (TLCJ differences were statislicaily significant and _ greater than predicted. In the tests of dynamic iung ** volumes, however, the insulators and controls showed no significant differences. The insulators' FEV,VFVC% was slightly loss than the controls arid their mean PFR was the same as that of the controls, although their predicted value was slight:;/ less, fn tests which, provide ar. indication of the efficiency of the iungs with respect to gas exchange the insulators had poorer results. For arterial Pc, and aivcolar-artcna! oxygen difference (A-aPo,) Trtt Static but* Tatums icn.i ERVd.l VC(I) RV d.l TLVd.) Ovnomti (wkj vafamei FEV,,d.) FVCd.l FEV.wFVC \ PFR (l./mm) Trtts related ta fn riffctff Mmuia voiuma d .) Vo/Vt Tl (ml/minnwnHg) XI (ml/mia/mmHg l ) Dm (ml/nuA'mfliHf) Vc (mil (mm) Pn, (mm) Pm, Iraaa) taaahtors 2-74 I -43 417 l-SS 5-71 TABLE 6 Lung Function Tests Coatrob i j Oiffertace ] Wflw(i'.i') i 2-7* -0-04 ,'0-t 1; 1-57 -0*14 (0-10) 4-36 -0-19(0-13) 1-78 -0-23 W1> 6*16 -0-45 '0-17) 1 l P j Predicted differeace i j due to one and keurhP j 0*70. P '-0-60 | O-20-P-.O-iO j 0-20 ? -0-i0 1 * 0 05 j * 001 -0*i0 -0-07 -- 0- i 9 3-05 4 22 72-4 442 4 3 20 4 35 73-6 492-5 -0-iJ -- 0-i J (0-13) -:-2 0-9) -0-1 (16-4) 0-20 -P'-O-iO 0-30 -P -0 2: 0-60 ? *0-50 100 ? *0*90 -0-07 -010 C2 -SI 73 319 20-0 445 33* 4) 0 24-0 45 6 35 3 105 0-SI fO-53) 0-20 *P -C IO 35-4 3-5 (2 !) 0*20 *P >0-10 21-1 -l-l (0-7) 0-20 -P -0-10 4-54 -0-09 (0-12) 0-50 -P -040 34-0 -0-2 0-90 -P -0-X0 44-8 -St 0-10 P -0 03 15-5 *6 (2-7) 93-4 -7-9 12-0l <0*01 1 .0-00i >5-7 0-4 (l-l) 0-70 -P -0-60 -- 0*6 0-02 0-2 0-i 1 'CotmdMSl; McGrath and Thomwn d*>4) (Kilt Hamar i l**j) iPm and Vt-j, the did P < ti-0 In sur which -.v than the The va'i with m asiumpt was repi series wt insulauo lands?/t sample v sample c Pats No. exuni No. not c> ", Examin Age (yr) Height fcir Exposure < Smoking a 0 grade I 2 3 The cc age, heigh they wer controls ! one had This con vedesprea control s' would pn asbestos I Belfast v asbestos 1 at necrop; Thus t controls a of expos j the effect! environnu The ,f H0BW8aiWS\*I -ihgKv^yt wiMUm .awsaamwAtt.'v-a lasulalkm workers m Belfast 255 ST0095355 tii -' ii'uU have 'i v were clearly It i\. however. . ntj awKiint for i i'k ('i) (liifvrencc i.li me of Jvlinite i' cvix-ncnccd . tm vittfoK and he i 'e tivtcvl dif- n* -. i *.c nivcn K \ 'M f . Mlh 4fUl 01..... 1 tu . `*e < lit- ' ' L.IVCV M.tl l\ .v k >rh .. t. 1 Ik I .ifHl 'mu *K him ii . thc difference* were significant If < 0-00! and to a-.tx.-sco-. were a history of cough and spuium P 0-01 respectively). and the presence of rales, increased hyponyehiai In nummary, the insulators had. on average, lung, angles, x-ray signs of pleural calcilkat.on and'or which were vnoller and lev* efficient at fa* exchange pulmonary' lihrovis. a reduction in static lung than the controh hut air (low wav unaffected. volume, a reduced arterial oxygen tension, and an increased alveolar-arterial oxygen difference. These Phnnilna arc the features generally associated with asbestosis. The clinical find.ngs of uyspnoca, cough, sputum, The validity of the prevent comparison of insulators clubbing, and rales have been commented on with matched controls depends on two main jvpcatcdiy (Ol.vcr. 1927; Seiler, 1928: McShane. assumptions - firstly, lhal the sample of insulators 1930; Mercwcthcr. 1933-4; Lynch and Smith. 1935; was representative and, secondly, that the control Lan/a. 1938; Wycrs, 1949; Knox, 1958; Perry. 1963; series was appropriate. As the entire population of Leachart. 1964; Hutchinson, 1965). In the present insulation workers was eventually examined (Lan-;- study, dyspnoea was commoner in the insulators landsrr a/., 1971 > it is possible to compare the present but the differ:' was not quite significant at the sample with the complete population (Table Ty. The conventional level of ? < 0-05. Measurement of the l sample examined appear* to be representative. hyponyehiai angle has been shown by Regan et at. (1967) to he a satisfactory index of clubbing. It is of interest that their mean result for normal fingers i TABLE 7 (1870) was greater than the present results in Pruint Sampu or Insulators Compaxid WITH EntWI POPULATION No. examined No not examined *. Examined Am fyr* Height (cm) Exposure <yr) Snvoktn# tahtt 0 ex *fde 1 2 J Prntnt tampit Entire population JO .1 94 304 169 161 252 20 3 40} 169 16-4 U (26*.) *M\> 5 (10*,) I t (2SV.| 10(20%) 40 (IS*.) 3) 02*;) 50(20%) 10 (32%) 51 (20*.) insulators (184-6. 186-0) which, in lum, were significantly greater than the present results in controls (180-4, 181-1). Diagnosis of asbestosis by x-ray appearances has been shown to be uncertain in the individual case (Williams and Hugh-Jones, 1960a). However, in the present comparison of groups of individuals there was a very clear difference, with only one abnormal x-ray in the control scries and 21 in the exposed series. A reduced arterial oxygen tension and a raised alvecicr-a.lerial oxygen difference have been reported by a number of workers (Wright, 1955; Williams and Hugh-Jones, 1960b; Bjurc, Sdderhoim. and Widimsicy. 1964). Reduced lung volumes without airway obstruction were also found, These arc also consistent with ;..c present study. Without the control group it would have been possible, from the radiological abnormalities, lo The conlrols closely matched the insulators in suspect the presence of asbestosis in the population ape, height, and smoking habit. As skilled tradesmen of insulators. 3ccuusc a control group was used, it they were of similar social class. Some of the was possible to prove that the rudielcjca! abnor ) controls bad occasional contact with asbestos and malities :n this population went usuociaicd with one had worked at an insulator for throe years. symptoms, signs, and abnormalities of lung function. This contact with asbestos probably reflects the It must be pointed out that the average disturbance widespread use of the material. The exclusion of a in lung function compared with the controls was j control subject because of contact with asbestos relatively mild despite the large excess of abnormal would probably not be justified since contact with chest x-rays, in addition there was only a small asbestos has been shown to be very common in excess incidence of dyspnoea. This suggests that * Belfast where Elmes and Wade (1965) found much of the dyspnoea was due to factors other than * asbestos bodies in the lungs of 20 to 25 % of ,-nun asbestos and is in keeping with the conclusion of | at necropsy. Langlands and her colleagues (1971) that smoking : Thus the comparison between insulators anti was associated with a greater impairment of iung s controls appear* valid and should reveal the effects function than was .v-ray abnormality. ; of exposure to insulating asbestos as distinct from the effects of living and working in ar. industrial environment. Cortciaxions v Th* features which were commoner in the in- The present study suggests that :hc flowing * sulaton and may be presumed to be due to expos"*' features arc useful in the diagnosis of asbestosis in Si- 21* ' WtUuim / \t Hyilurr and Jean // ./ ism*loads \ a population an abnormal t hen x-ray, the pretence of touch, sputusn. duhbsn* laarwri by measuring lie hyponyctual angle). and rain, and lung function lent which show a decrease in static volume, a reduced arterial oxygen lewason, and increased alveolar-arterial oxygen difference but no evidence of airways obstruction. Broun abnormalities in these respects may occur fairly commonly m any industrial population and because techniques vary somewhat from laboratory to laboratory, use of a control scries n important. This investigation was uiggratrri and encouraged by Professors O. L. Wade and P. C. Elmo. Assistance in questioning and examining the men was given by Mr. i. Collins. Mrs. M. Simpson, Miss A. Stevenson, and Miss S. Wheeler. Specimens of sputum were examined by Miss D. P. Bell. Chest jr-rays were taken under the supervision of Or. i. O. Y. Cole and read with his assistance and that of Profesaor Elmes. The computer programme was written by Dr, 1. D. Meittt. Employers, trades union and individual men co-operated willingly. One of us (W.F.M.W.) was supported by a Royal Victoria Hospital Research Fellowship and a Research Fellowship from the Chest and Heart Association. We wish to thank Min M. Wilkinson for typing the manuscript Ssder. M F.. Bader, . A.. Ticruein. A. S . and Selikoff. I. ) (1965). Pulmonary function in astmiosis: serial tests in a long-term prospective study. Atm. S. Y. Arad. Sri.. IJ2, 391-405. Bdlewicz. W. / (1964). Matched samples m medical in vestigations. Bril. J. prrr. jor. Mm/.. It, 167-173. 8jurr, }., Sdderhotm. B.. and Widiimky. J. (1964). Cardio pulmonary function studies in workers dealing with asbestos and glasswool. 7Wjr. 19,22-27. Campbell. E I. M (I960). Simptficalioa of Haldane's apparatus for measuring carbon dioxide concentration in respired gases in citascal practice. Brit. met. J.. I, 457-4ya. Comroe. J. H.. Forster. R. E,, Jr,. DuBois. A. ., Briscoe, W. A .andCarlsen. E. (1962). Tkt Lome: Cllnkml Phytiotrnrr and Pulmonary FamtHaa Ttili. 2nd ed. Year Book Medical PuNjshrrs, Chicago. Cotes. J. E. (1965). Laat Faatiiaa- Aursmrat aad ApftiraUoa la Medicine. Blackwell .Vwnlrtc PuMiealiOfia. Os lord. Elam. P. C .sad Wade.O. L. (1965). Betmnasliip bftwera exposure a asbestos end pUmraJ meligeaney m Bdfasi Aam A Y. Arad Sri . UL 5*6-557. nwebef. C. M , FBeea. P. PasrWaf. A. I. and Worn;. C. H. II959). The ugnMreae ef rwpsnnory sympsoim end the dwgnosn of efcrooic branduus in a working population. Brit. mtd. /.. 2. 257-266. Heaer. >1 A i. (1662) The gtfon of age on the rempenenis " <he pvtmofiary diffusing eapeeity. t'tln. Sri . U, 15-93. Hunt. R. <lw65i. Routine Jung func.ion siusitcs on a-o employees in an asbestos processing factory. Ann .V I' A. ad. Mi.. 132, 406-420. Huichinson. i. F. M. (1965). Symposium on asbcsiosis introductory lecture. Sneattle mtd. J.. 29. i2-16. Kaos. J. F. < 1956). The paciunouomoses and tbcsr control asbeslmis in Ihc manufacture of asbestos testiles. J mdutlr. Sonet. IB, 167-179. Unglands. Jean H. M.. and WaUace. W. r M 11965. Small Mood-samples from ear-lobe puncture: a sub stitute for arterial puncture. Lanrrl. 2, 315-317. ------.------ , and Simpson. Marion. J. C. (1971). Insulation workers in Belfast. 2. Morbidity in men still at work. Brit. J. indent. Mrd., 2B, 217-225. 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The s assess the effect - men cu v..'.;!y wo. 1 record which wi.': V ibis group of met. The mcf. were cor. i union and their err; i men were workin