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British Journal of Industrial Medicine 1982;39:344-348 PLAINTIFF'S EXHIBIT SII-649 Mortality of two groups of women who manufactured gas masks from chrysotile and crocidolite asbestos: a 40-year follow-up E D ACHESON,' M J GARDNER,1 E C PIPPARD.' AND L P GRIME-' From the MFC Environmental Epidemiology Unit.' Unnersuy of Southampton. Southampton General Hospital. Southampton S()9 4XY. and Lancashire Area Health Authority. Pendle and Rossenilale' Burnley General Hospital. Burnley BBH) 2R(J. UK abstract Two groups of women were exposed to asbestos while manufacturing gas masks in Lancashire before and during the second world war. One group (in Blackburn) is believed to have been concerned almost exclusively with the manufacture of civilian respirators (containing chrysotile) while the other (in Leyland) made respirators for the armed Forces (containing crocidolite) and a much smaller number of civilian respirators. Excess mortality ascribed to lung cancer and ovarian cancer were found at the second factory (statistically significant at the I % level) but not at the first. Mesothelioma was mentioned on the death certificates of five women who had worked in Leyland and one woman in Blackburn. The starting point of this study was an attempt to define two populations similar in other ways, exposed respectively 10 crocidolite and chrysotile asbestos in the manufacture of gas masks. It was known that the standard respirators issued to the armed Forces of the British Commonwealth before and during ihe second world war contained filters consisting of activated charcoal, merino wool, and West Australian crocidolite.' Studies of the mortal ity of factory workers employed in manufacturing Service respirators in Nottingham, England, and Ottawa, Canada, have been published.' ' Both groups of workers have suffered from excess mortal ity due to mesothelioma of the pleura and peritoneum. A study of women who worked in the Nottingham factory has also shown excesses of cancer of the lung and ovary.4 In Britain respirators were also manufactured to protect the civilian population. A contract was placed with a factory in Blackburn, Lancashire, in 1936 to manufacture more than 70 million civilian gas masks and work continued in ihis factory until the end of the war. From contempory data (Ministry Requests for reprints uv Professor E D Acheson Received 14 December 1981 Accepted 18 February 1982 of Supply, Home Office, and War Office papers 1927-45) and analysis of the contents of survisina masks, civilian gas masks are known to have con tained chrysotile. charcoal, and merino wool but not crocidolite. At Leyland. Lancashire, Ihe same firm operated a laclory thal from 1927 held a monopoly for the manufacture of gas masks tor ihe aimed Forces At tin unknown date in the 1930s these respirators were modified to contain crocidolite. and gas masks of the improved type continued to be manufactured there throughout the war and thereafter. Industrial gas masks containing crocidolite were made there until 1969 From the testimony of workers it is known that some civilian gas masks containing chrysotile were also made during the war at the Leyland fac tory Some workers travelled from Preston to work in the Leyland factory. We describe the mortality during i 95 I-80 of the two groups of female gas mask makers. The 570 women resident in Blackburn were working in 1939 at the factory that manufactured civilian respirators containing chrysotile. The 757 women resident in Leyland (435) and Preston (322) were engaged in1939 principally in manufacturing Service respirators and had been exposed to crocidolite but also to some chrysotile. They are referred to here after. for convenience, as the Leyland group. 344 DPMC-1276C LAM 019140 actured estos: a Oil mil Rnssendale' \ gas masks in is believed to irs (containing :s (containing cribed to lung mt at the 1 % >1 five women r Office papers nls of surviving n lo have cnnno wool but not firm operated a nopoly for the ined Forces. At cspiralors were .as masks of the ufactured there Industrial gas iade there until :rs it is known ning ehrysotile ic Leyland fac'reston to work 1951-80 of the ikers. The 570 orking in 1939 lian respirators ien resident in ere engaged in i ring Service eroeidolite but ferred lo hered group. Morialiiv of (wo groups of women who manufactured (jtfv masks 345 Method Using the National Health Service Central Register, staff of the Office of Population Censuses and Sur veys searched the records of everyone resident in September 1939 at Leyland, Preston, and Black burn. They identified those w' o occupations at that lime indicated that they were manufacturing gas masks. The vital status of these workers on 30 June 1980 was ascertained, and in the case of those who had died the date and cause of death was abstracted. The main analysis was restricted to women, thus excluding the 95 men employed at Leyland and the 58 employed at Blackburn. The number of deaths expected in these women was calculated using the person-years method,5 and compared with the number observed. Deaths from 1 January 1951 to 30 June 1980 were included, and five-year age group cause-specific death-rates for five-year calen dar periods were used to calculate the expected numbers.01 The rates used were for England and Wales as a whole, and an area correction was then incorporated into the analysis to adjust for local mortality during the years 1968-78. Although these years do not span the whole period of 195 1-80 they Table I Female gas musk makers by status, person-years offollow-up, anil urea Size of group Status at 30 June 1980 Alive Died (before 1 `>5 I) Died (after 195U) Embarked Person-years of follow-up from 1 January 1951-30 June l 98(1 Leyland \'<> t< 7S7 i 00 493 27 219 18 6^ 4 29 18 781 Blaikburn So % N 7(1 100 367 fS4 21 4 177 31 N1 14 324 are the only ones for which rates for Leyland, Pre ston, and Blackburn are available. Tests of the statistical significance of the observed number of deaths compared with the numbers expected are based on the Poisson distribution. I he average age of each group of women in 1939 was 28-3 years, although the spread of ages was sliehtk greater in Leyland than in Blackburn (the standard deviations are 8-7 and 7-2 years respec tively ). Results Table 1 shows the basic follow-up information on the women in each area. A few left England and Wales during the period, and their vital status sub sequent to embarkation is unknown. Also, the small number of deaths occurring before 1951 has been omitted from the main analysis as having only a short elapse time since exposure in 1939. Overall, about a third of each group have died, and most of those still alive were over 60 in 1980. In table 2 the general mortality experience of the two groups of women during 1951-80 is set out. Both groups showed a statistically significant excess of deaths from all causes combined compared with the numbers expected on the basis of rates for Eng land and Wales. In Leyland, after adjustment for local area mortality, this excess is principally due to deaths from cancer. On the other hand, for Black burn there is only a slight excess of deaths from cancer, but there is a large increase in deaths from other causes. On breaking the latter down into indi vidual causes the excess can be shown to be due to deaths from acute myocardial infarction (1CD No 4 I (I. Sill revision)." Mortality from malignant neoplasms is given by site in table 3 for the leading causes of death from cancer in women. Only sites with more than five Table 2 Mortality offemale gas mask makers in Levlaiul and Blackburn between I January I V.5 / and 30 June 1080. and relation to local area mortality Cause of death A rea All causes Levland Blackburn All malignant Leyland neoplasms Blackburn Other causes Lev land Blackburn Cos mask makers So of deaths Obs l,sp 219 l 85 177 12H 66 54 44 4 1 153 l U 133 88 SliWiltirilocit mnrtaiilv ratio SMK ! U 1 ! 8* 1 IX*' nn 1 19 135 16(1 123 9S 156 109 79 140 1 17 152** 99 l 27 137 1 80 Area Ratio \>us mask standardized niukers S \fR to nn>rtaht\ ratm area SWR (S\Ul\ lVf>8-7$ 1 10 l 117 1 !6 1 19* 9 5 1 >9* mi i'(l(v i 14 III! l 19 1 28* p < ti lls, "p < (Mil. L = Lower VS% contidence limn. U = Upper dSrr conlidence limit LAM 019141 346 Acheson, Gardner, Pippard, and Grime Table 3 Mortality from specify, cancers offemale xas mask makers in Leyland and film khurn between I January l 95 J and 30 June 1980, and relation to local area mortality Cause of death t Area Cancer of Momach (151) C .nicer of lung .ind pleura 11 r>2.1 b?) C ancer of hrcasi (174) Cjneer of cervix (1 HU) Cancer of ovarv (1 S3) Levland Blackburn Lev land Blackburn Levland Blackburn Lev land Blackburn Levland Blackburn Gas mask -nakers \'o of deaths Ohs , 4 1 5C) + IGp 44 11 <> 2 '(i it j: 11 4 5 i2 5 4X i2 4 -VI 24 4-4 3-4 Standardised muriates r<an/ SMR /. C 14 1 2't 2J 1 * ` 17 1v 1 2(w 111 yr 145 /7 1 15 12* 21 1 27V I4K IK Kl 5* 7 <, h'l 142 4X 2ux . 2u7 i '/ 4 o2 4X1 344 "P < (MJ1. L = Lower Wc confidence limit U = Upper 5r'-r confidence limn. TN'umbcrs in parentheses are Kih revision ICO code numbers * ^Numbers in parentheses are deaths from pleural mesothelioma A rea /Hurtaitlv ratio Ratio of ^a\ mask makers V 1/R to area SUR nt 1 2i 1 i? n-K2 107 2 25 " 04 1 54 ?x t 24 u 1 : 2b 1 14 o on 1 22 1 7.1 01 2-l'o` * *5 174 deaths are shown. There is a pronounced excess of deaths from lung and ovarian cancer in Leyland that is statistically significant after adjustment for local area mortality experience. If the two deaths from mesothelioma of the pleura at Leyland are excluded there remains an excess of deaths from lung cancer that is statistically significant at the 5% level. There was no excess mortality from cancers of the oesophagus, intestine, or rectum. 5r Cumulative fjo of deaths Observed decuhs * Expected deaths r MKSOI HELIOMA Mesothelioma was mentioned on the death certificates of five women at Leyland and of one woman at Blackburn. In three of the Leyland eases (two pleural and one peritoneal) mesothelioma was the underlying cause of death and in one case (pleural) it was mentioned as a contributory cause; in the remaining case (peritoneal) the death had been coded to carcinomatosis. The Blackburn ease of mesothelioma (pleural) was reported as the underlying cause of death. One additional death due to pleural mesothelioma was reported among the 95 men employed at Leyland, and two deaths in women (both at Leyland) were certified as due to asbeslosis. By contrast with the lour mesotheliomas certified as the underlying cause of death only (1-2 would be expected at the rates for England and Wales I RI-.NDS Ilf \! i) R 1 A LI I 1 W ft H TIML The figure shows the accumulated numbers of deaths since 1951 from cancer of the lung and cancer of the ovary in Leyland women compared with the accumulated expected numbers. For both types of cancer the observed numbers have risen faster than those expected, so that Ihe size of the numerical excess has continued to increase over -,`v-3% go x> 1950 50 Ai'nuntilnti'ii d,'iuh\ vmr /V5/ m I .cyltutd womvn from (al nifucr of the limit and lb) outucr of the ovary. lime up to 41) years after employment in the man ufacture of gas masks. I'he increasing difference is particulary pronounced for ovarian cancer. Interest ingly the deaths from mesothelioma in women all occurred after 1970--in 1972, 1974, two in 1975. I97.H, and 1979--although the male mesothelioma death took place in 1961. Discussion I wo aspects of the findings of this study merit further discussion. These are the significant excess mortality ascribed to ovarian cancer and the differ ences observed between the experience of the Leyland and Blackburn workers. Newhousc'1 was the first to suggest that there might be an association between exposure to asbes- DPMr- 12' LAM 019142 niiil (irime twn l(e/ : ,`f t'Hi rmiit rs V \!H !,, \ UR 'i from (at he man; rente is Inlcrcsi- mien all :n Iri75, lielioma y men! I excess . ilillei - lie I.ev il there i asbes Mortality of two i^roujis of women who manufactured u.tts musks .'47 tos and cancer of the ovary. A significant excess mortality (four observed deaths, 0-6 expected) from that cause was observed in her study of women exposed to chrysotile. amosite. and crocidolite at a factory in Barking that manufactured a wide variety of asbestos products, including the filters for both Service and civilian respirators. In a subsequent case-control study of patients with ovarian cancer exposure to asbestos was not identified as a risk fac tor.10 As none of the cases nor control patients had been exposed to asbestos, however, the population was inappropriate to test this hypothesis. Recently Wignall and Fox4 have shown a significant excess mortality from ovarian cancer in Nottingham women who manufactured gas masks containing crocidolite asbestos for the armed Forces during the second world war. The specification of these respirators is believed to have been similar to that of the Service gas masks manufactured at Leyland. No information is available about ovarian cancer in the Canadian gas mask makers but fewer than 100 women were exposed.1 The question must arise whether the excess num bers of deaths that have been attributed to ovarian cancer in this study and elsewhere have been cor rectly classified, or whether they represent cases of peritoneal mesothelioma. Deaths from peritoneal mesothelioma have also heen reported in each of the populations of women factory workers mentioned above who had an excess of ovarian cancer. From the earliest descriptions of peritoneal mesothelioma the difficulties of the differential diagnosis vis-a-vis ovarian cancer have heen emphasised. " The clini cal picture of secondary carcinomatosis of tile peritoneum and of peritoneal mesothelioma is simi lar, and clinicians may be forgiven if the possibility of a rare industrially related tumour does not come to mind, particularly in a female patient. The chest radiograph does not always show evidence of previ ous exposure to asbestos in cases of peritoneal mesothelioma.11 A comparison between the mortality patterns of the Blackburn and Leyland workers shows that the significant excesses of mortality from lung and ovarian cancer (and all but one of the cases of mesothelioma) occurred at Leyland. If the study had been limited to Blackburn it would not have been possible to make a convincing case that there had been an excess risk of cancer associated with the manufacture of gas masks. The probable explanation for the differences bet ween Leyland and Blackburn lies in the different nature of the exposures in the two factories. The most obvious difference was that at Leyland crocido lite was the principal type of fibre to winch the women were exposed while at Blackburn chrysotile was the onl\ n.pe ol asbestos used. 1 lie other con stituents of the filters--charcoal and merino wool--were common to both factories. There were other differences, however The Service respirators at Leyland were made "by hand to a high standard" while at Blackburn, to cope with the massive order for civilian masks, manufacture was mechanised. The Leyland factory had been in operation finger before lri?y than had the Blackburn factory. Thus, in addition to the known differences in types of asbestos fibre in use in the two factories, there may also have heen unknown differences in dose and duration of exposure. Nevertheless, the pattern of mortality is consistent with the view- that mesothelioma (and possibly ovarian cancer) is par ticularly associated with exposure to crocidolite. It should he pointed out that nothing is known ol the industrial history of the women in the two cohorts before and after tric'd. A second factory opened in Blackburn in 1 ri41 to manufacture Ser vice respirators containing crocidolite. According to the testimony of survivors this work was on a small scale, and there was little exchange between the two workforces. Several cases of mesothelioma are known to have occurred in this workforce (A J Maxwell, unpublished observations) Morgan and Holmes14 have recently reported three eases ol pleural mesothelioma at Blackburn in each of which amphihole asbestos fibre was lound in samples ot lung tissue. In two ol these occupational exposure is stated as starting in I ri4 I. the other being unknown We have reason to believe that the Blackburn patient with pleural mesothelioma in our material transferred to the second Blackburn factory. We would like to thank Dr C Osmond for his help with the computing work. References 1 Jones JSP, Pooler PI). Smith P( < Factors populations exposed to croailohie asbestos--.1 eontinuinu curves /VS/ KM I ! IT- :n Junes JSP, Poole; PlJ Smith P(>, etui I he consequences 0/ exposure >" ashestos Just in a wartime lias mask I'aelorx /VW KM mW s; McDonald AD, McDonald J(. Mesothelioma alter crocidolite expoMite durme eas mask m.imd icUire /nurmi Re\ I `>7K. I 7 '40 f. SSiLtnall Bk. J'ox V. Modulus ol kntalc mis mask assemblers. fir J /mi McJ | dKllJM 14-X I lill ID ( om|,(iiuig man scars at risk Hr J l're\ So, M,-,i D/7:.26 I V-4 'Olltce ol Population ( ensu*>es and Sursesv (timer -norm/us / u^larui ./((,/ W tilts, /'/// Tf/ lomlon IlMSO. I'v?-' Olhcc ol Populwltoi 1 ( disuses and Surscss (ame> rnoruthn m / mahout jin! IV ,//( \ /</?/ ~S lomlon }IMS() DvMi *VSofld Ikahh ( P earns,it ton t m, r nutimuii < lu\\tfu t/uoti 0/ ,!i\ eus, 'V//i rrviM,,ti (leiicsu \S i It >. |lu>7 * Nev.house Ml.. Burrs ( SVacncr K'. lurok Ml- \ studs ol the LAM 019143 54,K m.ifij.'iiv tif" Icnijlc workers Hr J Hut '/./ 29 154-41 Nc-aj:.u\c ML. Pears,m KM. l uilcri.m JM Mucsui P-\M. Sn.ni- son MS A ca*; conm.l study ul Laremoma of ihe Hr J Prev Sue Sled 1 977.3 1.1 -IK- 5 5 Wrdlow M. Mesothelioma *.!' die pelvic pel it< me uni rescmhhnc ;\ipti(jry e\xi;idciuc,tre.moma .( the ovary. Ant J (>huct G.m'itii Iv5^.77.iw7-:(iu Achc\nn, Cantncr, Vippanl, and (innw kc.tl t I- \>l'Oi..MX I, i:; 1 O till! ..I................ III'1 | li.l'O.IV , (han I'M- Haitour f U (V-urU IB. Smiih IT. IVrnmu\iJ iliesolhcluima Hr I \,,lt; I * 1 ' (-2 W< * Mi,ijem \ ll.-lni.v \ t oiKCHU.iinnis and eharaeicnsnes of .iiuplnhuk hhro in ihe lungs nt workers exposed H* croeidnlitc in ihe British n.rs musk I.alone-. ami elsewhere, dunny the second uni id .v,r Hr J hul Med :VKi;.W<0-h l i i Vancouver style All manuscripts submined to the Br J hul Med should conform to the uniform requirements for manuscripts submitted to biomedical journals (known as the Vancouver style). The Br J hid Med, together with many other international biomedical journals, has agreed to accept articles prepared in accordance with the Vancouver style. The style (described in full in Br Med J, 24 February 1979, p 532) is Intended to standardise requirements for authors. References should be numbered consecutively In the order in which they are first mentioned in the text by Arabic numerals above the line on each occasion the reference is cited (Manson1 confirmed other reports2-5 . . . ). fn future refer ences to papers submitted to the Br J Ind Med should include: the names of all authors if there are six or less or, if (here are more, the first three followed by ct id: the title of journal articles or book chapters; the titles of journals abbreviated according to the style of Index Medicwt; and the first and final page numbers of the article or chapter. Examples of common forms of references arc: 1 International Steering Committee of Mcdtcul Editors. Uniform requirements for manuscripts submitted to biomedical journals. Hr Med J 1979;1:5 5 2 - 5 - 1 Soter NA. W'asscrman S!, Austen Kl;. Cold urticaria: release into the circulation of histamine and eosino phil chemotactic factor of anaphvlaxis during cold challenge .V F.ngi J Med 1976;294:687-90. 1 Weinstein L. Swartz MN. Pathogenic properties of invading micro-organisms. In: Sodeman WA Jr, Sodcman WA. eds. Pathologic physiology: mechanisms of diseau'. Philadelphia: W 0 Saunders, 1974:457-72. A: W RH- from ~ School School. abstra asbeste Welling togethe. Gold's r in 13% for men bodies in found a' was fou.n prevalent its prev-i after the In l^n on asbc-' Zealand/ to tdcnti:;. found 3rr tion me'.r. ,. bodies ir. j.' tos bodies primary tuttxfrom twocc initial South*sections oaS was exaraat- serics o( digested l removed 1 available I the fte differrtCd inflated* out tkrt. cal i LAM 019144