Document 2gjr128rR8XNeJK44LmoEqQ6

Stand J Work Environ Health 1989:13:4 Mortality of auto mechanics A ten-year follow-up by Eva S Hansen, MD, PhD1 HANSEN ES. Mortality of auto mechanics: a ten-year follow-up. Scant! J Work Environ Health 1989:13: 43--44. This study was set up to investigate whether work in car repair workshops is associated with an increased risk of ischemic heart disease and specific malignant neoplasms. For this purpose, a cohort of auto mechanics has been followed through 10 years with regard to cause-specific mortality. Comparisons were made with another cohort of skilled male workers who were not exposed to asbestos or petrochemi cal substances. The auto mechanics' mortality was increased for ischemic bean disease [standardized morulity ratio (SMR) 121,93 9 confidence interval (93 9k Cl) 102--143), other cardiovascular diseases (SMR 112.93 9k Cl 82--130), cancer (SMR 113.95 9k Cl 97--134), other diseases (SMR 119.93 9k Cl 94--149). and external causes (SMR 131.95 % Cl 113--153). For specific cancer sites, increases were seen for pan creatic cancer, urinary cancer outside the bladder, and pleural mesothelioma. Key terms: asbestos, car repair, carbon monoxide, ischemic heart disease, mesothelioma, occupation, pan creatic cancer, petrochemical substances, polycyclic aromatic hydrocarbons, urinary cancer. i 1 The work environment of auto mechanics involves Auto mechanics constituted the exposed pan of the potential exposure to asbestos, mineral oils, solvents, study cohon. The comparison population, ie, the un paint pigments, anticorrosive substances, and automo exposed part of the study cohon, was made up of other bile exhaust. The literature on work-related health haz specific groups of skilled workers. ards is sparse regarding auto mechanics. Increased risks The members of the study cohon were identified of both bladder cancer and lung cancer have been from the files of a nationwide census carried out in reported (1--3). In addition a few cases of malignant Denmark on 9 November 1970. Self-reponed occupa mesothelioma have been reported for auto mechan tion, trade, industry, and employment on the day of ics, especially among persons employed in brake service the census was recorded for all the Danish inhabitants centers (3--5). With regard to other occupational older than 14 years of age. These data were used to groups whose exposure may resemble that of auto select the persons included in the study. mechanics, increased cardiovascular mortality has been The study comprised only skilled workers and ap reported for motor vehicle examiners (6), whereas in prentices, only men between 15 and 74 years of age. creased mortality from digestive cancer has been found and only persons who were occupationally active (ie, among automobile manufacturing workers and other employed) on the day of the census. Everybody with metal workers (7, 8). the title "auto mechanic" or "mechanic, employed at The actual study was set up to investigate further a car-repair workshop" was included as an exposed the potential health hazards associated with the com person. As unexposed persons alt men with one of the plex exposure situation typical for the work environ following job titles were included (proportion of to ment in Danish car repair workshops. Malignant ne tal comparison group in parentheses): carpenter oplasms of the respiratory system, the urinary system, (45 ?), electrician (32 %), instrument maker (13 %), and the upper digestive organs were anticipated to be dairyman (5 %), upholsterer (3 %), or glazier (2 ^i). of particular interest, together with cardiovascular dis Table I shows the number of exposed and unexposed eases. 3) Sublets and methods persons in ten-year age groups. The Danish National Bureau of Statistics has linked the records of the 1970 census with the current cen tral register of persons and the national register of The research design was that of a historical cohort deaths [publications numbers 37 (1979) and 41 (1985) study in which the exposed pan of the cohon was com from the Danish National Bureau of Statistics, both pared with the unexposed part in terms of cause-spe in Danish]. This procedure has enabled the total cen cific mortality through a ten-year period of follow-up. sus population to be followed for 10 yean. The ac tual study cohon formed pan of the census popula ' Institute of Community Medicine. University of Odense. tion and was traced by the use of the existing register Odense. Denmark. linkage. The study persons were traced until 8 Novem Reprint requests to: Dr ES Hansen, Institute of Community ber 1980 or till death or emigration prior to this date. Medicine. J B Winstowsvtj 17. DK-5000 Odense C. Denmark. The follow-up data are shown in table 2. The auto m HWBUI0007504 1* Table i. Number of exposed persons (auto mechanics) and the comparison population of unexposed skilled workers by age. Age (yearsl on 9 November 1970 15--24 25--34 35-44 45-54 55-64 65--74 15--74 Auto mechanics N% 13 882 4 661 1 545 949 662 101 64 21 7 4 3 0.5 21 800 100 Comparison population N% 25159 12 633 6118 3 976 3146 713 51 747 49 24 12 8 6 1 100 Table 2. Follow-up data for the auto mechanics and the com parison population of skilled workers from 9 November 1970 through S November i960. Number of deaths Number of emigrants* Number of persons alive and living In Denmark at the end of the follow-up Auto Comparison mechanics population 586 1 903 561 1665 20 633 48179 Includes persons lost to follow-up. The register linkage did not allow for separating emigrants and persons lost to fol low-up. comparison population and the number of personyears at risk accumulated by the auto mechanics. For the statistical evaluation, the observed numbers of deaths beyond 100 were assumed to follow a nor mal distribution (Yates' correction was employed), whereas, for smaller numbers, a Poisson distribution was assumed. The death rates of the comparison popu lation were assumed not to be influenced by random variation. Confidence intervals (Cl) for the stan dardized mortality ratio (SMR) were calculated by the method proposed by Miettinen (9) whenever the ob served number of deaths exceeded 100. For smaller numbers of deaths, exact Poisson limits were calcu lated (10). Results The number of deaths observed among the auto mechanics exceeded the expected number by 21 %. The increased mortality was not confined to any single group of causes of death (table 3). As regards specific cancer sites, increases were seen for pancreatic cancer, pleural mesothelioma, and uri nary cancer outside the bladder (table 4). Discussion Tsble X Mortality of Danish auto mechanics In 1970--1980. (SMR = standardized mortality ratio. 95 % Cl = 95% confi The auto mechanics' mortality has been evaluated dence interval) against that of skilled men in other trades, free from Cause of death* Ob Ex served pected SMR number number 95% a occupational exposure to petrochemical products, as bestos, and paint pigments. However, some of the per sons included in the comparison group may have been Cancer (140--209) 146 128.8 115 97--136 occupationally exposed to other agents associated with 1 Ischemic heart increased mortality from, eg, cancer. In this case, a disease (410--*14) 132 108.7 121 102--145 potentially increased risk for auto mechanics may have Other cardio been masked. vascular diseases (390-404, 420--456) 46 41.0 112 82--150 According to the concept introduced by Hemberg Other diseases 76 64.0 119 94--149 (II), the actual cohort study was rather insensitive. Externa) causes Only occupationally active and therefore healthy work (EOOO-E999) 175 1333! 131 113--153 ers were enrolled in the cohort, and the period of fol ] Unknown Total 6 5.9 101 37--220 low-up was rather short. "Exposure" was defined by 583 481.5 121 a person's occupation and industry and determined at 112--131 one point in time, namely, the day of the census. In The code of the International Classification of Diseases Denmark skilled workers tend to stay in one industry (eighth revision) in parentheses. throughout their worklife. Thus, for the actual study, the census data may represent a reasonably good proxy for lifetime occupation and industry. However, the mechanics and the comparison population of unex crudeness of the employed definitions dilutes the ex posed skilled workers contributed 192 300 and 481 642 posure contrast under study, and some effects of the person-years at risk, respectively, to the study. auto mechanics' work environment may have gone un Deceased persons, emigrants, and persons lost to fol detected. low-up contributed person-years at risk up until the Selection of the occupational groups included in the day of death, the day of emigration, or the last day comparison population enabled the group to resem of notification in the central register of persons. ble auto mechanics with respect to work-related de For deceased persons, information on the underly mands on physical strength and fitness, social class ing cause of death was derived from the death certifi membership, and geographic distribution. In spite of cate. The numbers of deaths expected for the auto this group control for social class, life-style habits may mechanics were calculated from the death rates of the have differed between the compared populations. The 44 HWBUI0007505 f*&) 4. Dsnish auto mechanics' mortality from specific malignant neoplasms in 1970--1980 (SMB = standardized mortality ratio. 95 V. Cl = confidence interval) Cancer site* QDsr*C number E*pcteCf number SMR 94 % Cl Esophagus (150) Stomach (151) Pancreas (157) Otner digestive organs (152--156, 156--159) Bronchus and lung (162.1) pleura (163.0) Other respiratory organs (160--162.0, 163.1--163.9) Bladder (166) Other urinary organs (169) Other sites (140--149, 170--187, 190--209) Total (140-209) 4 3.4 116 32- 298 7 6.6 104 42--214 17 7.8 219 128--351 16 17.0 94 54--153 41 40.7 101 72-137 t 0.0 1 0.3 400 10--2229 4 4.1 98 27--250 e 4.6 174 75-343 49 M2 111 62--147 148 128.8 115 97--136 The code ol the International Classification of Diseases (eighth revision) in parentheses. auto mechanics' high mortality from external causes points to differences regarding risk-taking behavior. On the other hand, the fact that no differences were found for lung cancer indicates that the results have not been positively biased by smoking habit differ ences. Actually, smoking is prohibited in many places in car repair workshops, and the auto mechanics may in fact have smoked less than the persons in the com parison group. The number of deaths ascribed to ischemic heart dis ease exceeded the expected number by 21 Vs, an ef fect which is of the same order of magnitude as that of smoking 1--14 g of tobacco per day (12). The ob served excess of deaths from ischemic heart disease is remarkable, particularly in view of the rather short period of follow-up. Ischemic heart disease usually has a protracted course rich in symptoms and increasing disablement. Persons with symptoms of cardiac ische mia are rare among active blue-collar workers, and with short-term follow-up one usually finds a very low mortality due to ischemic heart disease in such groups. The difference between the auto mechanics and the comparison group with respect to ischemic heart dis ease may either be due to specific occupational ex posures or to confounding by life-style factors. With regard to the latter, smoking can be ruled out because of the aforementioned lack of difference in lung cancer mortality between the groups. Hypothetically, the com pared populations may have differed in dietary habits or leisure-time activities. However, such differences would have had to be unusually extreme to bring about an effect equaling the actual order of magnitude. With respect to work-related hazards, the auto mechanics may be exposed to suspected atherogens like carbon monoxide and polycyclic aromatic hydrocarbons through the inhalation of automobile exhaust and dur ing the handling of petrochemicals such as, eg, anticor rosive substances, solvents, and mineral oils. Previous ly, a slight increase in cardiovascular mortality (SMR 105) has been reported for motor vehicle examiners. whose exposure may resemble that of auto mechanics (6). Pancreatic cancer occurred in excess among the auto mechanics. However, for such a rare disease, the com parison population may have been too small to justi fy the assumption that random variation has not in fluenced the death rates. Therefore, reservations should be made as to the statistical evaluation of the data on mortality from pancreatic cancer. Little is known about the etiology of pancreatic cancer. Tobac co smoking seems to be of importance, alcohol not (12--15). Studies on occupational mortality have in dicated that this cancer site is associated with work in the metal industry (7, 8), the chemical industry (16, 17). especially in the production of bcta-naphihylamine and benzidine (18), and with exposure to petroleum products (19, 20). Animal assays have pointed out nitrosamino compounds, acetaminofluorene. p-di- methylaminoazobenzene, and methyinitrosurea as car cinogens with affinity to the exocrine pancreas (21--24). The chemical substances in the auto mechan ics' work environment may include nitrosamino com pounds formed from, eg, sodium nitrite and triethanol amine. both of which are in current use as mineral oil additives. __ Asbestos exposure is known to occur during the replacement of brake linings, and the single case of pleural mesothelioma is an indication that this exposure has not been negligible. On the basis of this back ground, it is remarkable that the auto mechanics' lung cancer mortality was not increased. The possibility that smoking has been less prevalent among the auto mechanics than in the comparison group has already been mentioned. If present, such a difference would result in negative confounding as regards lung cancer and other tobacco-related diseases. ____ For specific cancer sites other than lung cancer and pancreatic cancer, the observed numbers of death were too small to state or rule out a potentially increased risk. 45 HWBUI0007506 Acknowledgments The author thanks Mr O Andersen of The National Bureau of Statistics for providing the possibilities to make use of census records. This work was supported by a grant from The Dan ish National Anti-Cancer League. References 1. Smith EM, MiUer ER. Woolson RF. Brown CK. Blad der cancer risk among auto and truck mechanics and chemically related occupations. Am J Public Health 1985:75:881--3. 2. Schwartz E. Proportionate mortality analysis of automo bile mechanics and gasoline service station workers in New Hampshire. Am J Ind Med 1987;12:91-9. 3. Jarvholm B, Brisman J. Asbestos associated tumours in car mechanics. Br J Ind Med (in press). 4. Elliehausen HJ, Paur R, ROdebperger K. Woitowitz HJ. Zum Risiko von Asbestinhaialionsfolgen bci Kraftfahrzeugmechanikem in Bremsendiensten. Arbeitsmed Sozialmed Praeventivmed 1985:11:256--61. 5. Paur R. Woitowitz HJ, Rodelsperger K, Jahn H. Pleuramesotheliom nach Asbeststaubgefkhrdung bet Bremsreparaturen in Kfz-Handwtrk: Kasuistische Beobachtungen. Pra* Klin Pneumol 1985:39:362--66. 6. Stern FB, Lemen RA. Curtis RA. Exposure of motor vehicle examiners to carbon monoxide: a historical prospective study. Arch Environ Health 1981:2:59--65. 7. Vena JE, Sultz HA, Fiedler RC. Barnes RE. Mortality of workers in an automobile engine and parts manufac turing complex. Br J Ind Med 1985:42:85--93. 8. Milham S Jr. Cancer mortality patterns associated with exposure to metals. Ann NY Acad Set 1976:271:243--9. 9. Miettinen OS. Simple interval-estimation of risk ratio. Am J Epidemiol 1974;100:515-6. 10. Documents Geigy, mathematics and statistics. 5th ed. Copenhagen: Ciba-Gcigy, 1975:107. 11. Hernberg S. "Negative" results in cohort studies -- how to recognize fallacies. Scand J Work Environ Health 1981:7 (suppl 4): 121--6. 12. Doll R, peio R. Mortality in relation to smoking: 20 years' observation on male British doctors. Br Med J 1976;2:1525-36. 13. Mack TM. Yu MC. Hanisch R. Henderson BE. Pan creas cancer and smoking, beverage consumption, and past medical history. J Natl Cancer Inst 1986:76:49--60. 14. Velema JP, Walker AM. Gold EB. Alcohol and pan creatic cancer. Epidemiol Rev 1986:8:28--41. 15. Williams RR. Horm JW. Association of cancer sites with tobacco and alcohol consumption and socioeconomic status of patients: interview study from the third national cancer survey. J Natl Cancer Inst 1977;58:525-47, 16. Li FP, Fraumeni JF, Mantel N. Miller RW. Cancer mor tality among chemists. J Natl Cancer Inst 1969:43:1159-- 64. 17. Olin GR, Ahlbom A. Cancer mortality among three Swedish male academic cohorts: chemists, architects and mining enginecrs/meialiurgisis. Ann NY Acad Sci 1982;381:197-201. 18. Mancuso TF. El-Attar AA. Cohort study of workers ex posed to beta-naphthyiamine and benzidine. J Occup Med 1967:9:77--85. 19. Lin RS. Kessler JJ. A multifactorial model for pancreatic cancer in man. JAMA 1981:245:147--52. 20. Norell S, Ahlbom A, Olin R. et al. Occupational fac tors and pancreatic cancer. Br J Ind Med 1986:43: 775--8. 21. Hoch-Ligeti C. Primary pancreatic tumors in rats fed p-dimethylaminoazobenzene. Br J Cancer 1949;3: 285--9. 22. Pour P, Salmasi SZ, Runge RG. Selective induction of pancreatic ductular tumors by single doses of N-nitrosobis(2-oxopropyl)amine in Syrian golden hamsters. Cancer Lett 1978:4:317--23. 23. Reddy JK, Rao MS. Pancreatic adenocarcinoma in in bread guinea pigs induced by N-methyl-N-nitrosurea. Cancer Res 1975:35:2269--77. 24. Wilson RH. DeEds F, Cox AJ. The toxicity and car cinogenic activity of 2-acetoaminofluorene. Cancer Res 1941;1:595-607. Received for publication: I July 1988 46 HWBUI0007507