Document e881zM4B62x0wEZa1R1K5QBm

British Journal of Industrial Medicine 1982;39:344-348 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,' E C PIPPARD,' AND L P GRIME2 From the MRC Environmental Epidemiology Unit,' University of Southampton, Southampton General Hospital, Southampton S09 4XY, and Lancashire Area Health Authority, Pendle and RossendaIe> Burnley General Hospital, Burnley BBIO 2PQ, 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 1 % 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 to 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 the second world war contained filters consisting of activated charcoal, merino wool, and West Australian crocidolite.1 Studies of the mortal ity of factory workers employed in manufacturing Service respirators in Nottingham, England, and Ottawa, Canada, have been published.1-5 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 this factory until the end of the war. From contemporv data (Ministry Requests for reprints to: 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 surviving masks, civilian gas masks are known to have con tained chrysotile, charcoal, and merino wool but not crocidolite. .. At Leyland, Lancashire, the same firm operated a factory that from 1927 held a monopoly tor the manufacture of gas masks for the armed Forces. At an 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 1951-80 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 in 1939 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. Mortality of two groups of women who manufactured gas 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 whose occupations at that time 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.67 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 1951-80 they Table 1 Female gas mask makers by status, person-years offollow-up, and area Size of group Status at 30 June 1980: Alive Died (before 1951) Died (after 1950) Embarked Person-years of follow-up from I January 1951-30 June 1980 Leyland No % 757 100 493 65 27 4 219 29 18 2 18 781 Blackburn No % 570 100 367 64 21 4 177 31 51 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. The average age of each group of women in 1939 was 28-3 years, although the spread of ages was slightly greater in Leyland than in Blackburn (the standard deviations are 8-7 and 7-2 years respec tively). I. /\6+aU iMo/\fc*s Results ftVtfJ slujy Table 1 shows the basic follow-up information c Z. Soihc the women in each area. A few left England ar (css) Wales during the period, and their vital status sul sequent to embarkation is unknown. Also, the sms ?. is ef MM haJ number of deaths occurring before 1951 has bee di'U (z($ sRt( fa JtiJj omitted from the main analysis as having only short elapse time since exposure in 1939. Overa about a third of each group have died, and most those still alive were over 60 in 1980. oaJ gw 6o (cbitAUf tMcth ? In table 2 the general mortality experience of tl two groups of women during 1951-80 is set ot Both groups showed a statistically significant exce of deaths from all causes combined compared wi the numbers expected on the basis of rates for En land and Wales. In Leyland, after adjustment f local area mortality, this excess is principally due deaths from cancer. On the other hand, for Blac bum 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 (ICD No 410, 8th revision).8 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 Leyland and Blackburn between 1 January 1951 and 30 June 1980, and relation to local area mortality Cause of death Area Gas mask makers . No of deaths Standardised mortality ratio Obs Exp SMR L u All causes Leyland 219 185 118* 103 135 Blackburn 177 128 138** 119 160 All malignant Leyland neoplasms Blackburn 66 44 54 123 41 109 95 156 79 146 Other Leyland 153 131 117 99 137 causes Blackburn 133 88 152** 127 180 'P < 0 05. "p < 0 01c * Lower 95% confidence limit. U < Upper 95% confidence limit. Area mortality ratio Ratio gas mask makers SMR to area SMR 110 1-07 116 1-19* 95 1-29* 103 106 114 103 119 1-28* 348 Acheson, Gardner, Pippard, and Grime mortality of female asbestos workers. Br J hid Med 1972;29:134-41. Newhouse ML, Pearson RM, Fullerton JM. Boesen EAM, Shan non HS. A case control study of carcinoma of the ovary. Sr J Prcv Soc Med 1977:31:148-53. 11 Swerdlow M. Mesothelioma of the pelvic peritoneum resembling papillary cyst adenocarcinoma of the ovary. Am J Obsiei Gyr-'-'i 1 QSQ;77:197--200. 11 Keal EE. Asbestosis and abdominal neoplasias. Lancet 1960;ii:12l 1-6. ,J Chan PSF, Balfour TW, Bourke JB, Smith PG. Peritoneal mesothelioma. Br J Surg 1975;62:576-80. " Morgan A, Holmes A. Concentrations and characteristics nf amphibole fibres in the lungs of workers exposed to crocidolite in the British gas mask factories, and elsewhere, during the second world war. Br J hid Med 1982;39:62-9. Vancouver style All manuscripts submitted to the Br J hid Med should conform to the uniform requirements for manuscripts submitted to biomedical journals (known as the Vancouver style). The Br J Ind 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 ...). In 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 there are more, the first three followed by et ah, the title of journal articles or book chapters; the titles of journals abbreviated according to the style of Index Medicus; and the first and final page numbers of the article or chapter. Examples of common forms of references are: 1 International Steering Committee of Medical Editors. Uniform requirements for manuscripts submitted to biomedical journals. Br Med J 1979;1:532-5. 1 Soter NA, Wasserman SI, Austen KF. Cold urticaria: release into the circulation of histamine and eosino phil chemotactic factor of anaphylaxis during cold challenge. N Engl J Med 1976;294:687-90. 1 Weinstein L, Swartz MN. Pathogenic properties of invading micro-organisms. In: Sodeman WA Jr, Sodeman WA, eds. Pathologic physiology: mechanisms ofdisease. Philadelphia: W B Saunders, 1974:457-72.