Document ZBxYoeK2wwyme0BVB74x2Yrz7

Reprinted from Journal of Occupational Medicine Volume 27,No. 6,June 1985 I [""1 Texaco Mortality Study c 1. Mortality Among Refinery, Petrochemical, and Research Workers Barbara j. Divine, Ph.D.; Virginia Barron, M.S.; and Samuel D. Kaplan, M.D. The Texaco mortality study is a retrospective follow-up study of a l l persons who were employed for at leastfive g the period 7947 through 7977. O f the 19,077 white men in the cohort, 74,609 were alive, 4,024 were known to be dead, and the vital status o f the1r winrr 444 was unknown as o f Dec. 31. 7977, The standardized mortality ratio (SMRI of 75 for a l l causes was significantly low, on the basis o f u e x p e c t e d deaths. Statistically significant deficits also were seen for all major causes of death and for cancer of many sites, including lung, stomach, bladder, and colon. The SMR was greater than 700 for six causes of death: pancreas cancer, brain cancer, leukemia, Hodgkin's disease, other lymphatic cancer, andbenrgn neoplasms. However, none of these increases was statistically significant, and all SMRs except that for benign neoplasms (SMR= 748) were under 779. A number of frequently cited studies have exam- ined patterns of mortality among petroleum workers. While most have shown overall standardized mortality ratios (SMRs) to be lower than those of the general population, elevated numbers of deaths have been observed for cancers of several sites, including lung,l-3skin,'.'.` nasal cavity and digestive s y ~ t e r n ,m~ -a~lignant brain,'.q.b pan~reas,~k.'idney,' lymphoma,b.B leukemiadi.b and bone.'' However, the elevations are not found consistently in all the studies. This report concerns the cohort of white males who were employed five years or more at Texaco refineries, research laboratories, or chemical plants and who worked any time during the period 1947 through 1977. The major objective of the study was to determine the patterns of mortality among these workers and, in particular, to determine i f any o f the elevated causes of death found in From Texaco Inc., Houston (Dr. Divine and hls. Barron); and SRI International, Menlo Park, Cali. (Dr. Kaplan). Address correspondence to 1 Allen Center, P.O. BOX I4M. H o w ton, TX 777-51 (Dr. Divine). Journal of Occuoational MedicineNol 27. No 6iJune 1985 other petroleum worker populations also occurred in the Texaco population. Materials and Methods The studv cohortconsists of all employees of Texaco Inc. who worked at the refinery, petrochemical, and researcn tacilities for a minimum of tive years prior to Uec. 31, 1977, with at least one day of employment between `Jan. 1, 1947, and Dec. 31, 1977.. These employees were identified from personnel system rosters of all employees who separated from the company between 1947 and 1978 and from personnel listings of employees active in 1978. (Information on the rosters of separated employees included only the last job; therefore, employees who transferred to other facilities could not be identified. However, most transfers involved management personnel. Also excluded were employees of the administrative, engineering, and medical services departments and employees a f a former subsidiary who terminated before 1955 and whose work records were not retained.) Data collected on each employee included name, Social Security number, race, sex, date of birth, and a complete occupational history, when available. Vital status information for former employees was obtained from company records, where available, or from the Social Security Administration. Copies of death certificates were obtained either from the work record or trom the state where the death occurred. The underlying cause of death identified on each death certificate was coded by a nosologist according to the seventh revision ot the lnternational Classification o f Diseases for deaths through 1967and according to the eighth revision for deaths occurring after 1967. All codes were converted to the seventh revision for the analysis. In the analysis of mortality, persons for whom vital status was unknown were assumed to have been..l.ost on the date last employed. Analysis was done using the Monson com- d puter program'" to compare the observed and expected number of deaths using the US. white male population as the comparison group. Person-yearswere counted beginning either on the date when the employee had worked five years or on the study begin date, Jan. 1, 1937, which- 445 SMRs for Selected Causes of Death Among White Males, 1947 Through 1977 Cause (ICD Seventh Revision) Observed No. Expected No. 95% of Deaths of Deaths SMR Confidence Interval All causes (001-998) All infective 8, parasitic diseases (001-138) All cancer (140-205) Caacer of digestive system Cancer of stomach Cancer of large intestine Cancer of pancreas Cancer of lung Cancer of prostate Cancer of kidney Cancer of bladder Cancer of skin Cancer of brain Lymphosarcoma Hodgkin's disease Leukemia Cancer of other lymphatic tissue Benign neoplasms Endocrine, metabolic diseases Vascular lesions of central nervous system Diseases of circulatory system Arteriosclerotic heart disease Respiratory diseases Emphysema Diseases of digestive system Cirrhosis of liver Diseases of genitourinary system External causes of death Accidents 4,024 22 767 215 45 64 62 182 62 24 19 14 &31 25 20 78 322 1,975 1,623 159 52 141 56 43 227 152 5,331.8 80.3 1,019.4 306.8 63.9 94.3 57.7 306.0 73.1 25.1 33.9 16.7 28.0 &22.2 21.8 13.5 99.6 406.2 2,495.7 2,010.6 303.8 86.1 252.1 120.0 81.o 423.7 289.0 75 27 75 70 70 68 107 59 85 96 56 84 &111 115 148 78 79 79 81 52 60 56 47 53 54 53 73-78 -17-41 70-81 61-80 51-94 52-87 82-138 51-69 65-109 61-142 34-87 646-140 75-157 74-170 91-229 62-98 71-88 76-83 77-85 45-61 45-79 47-66 35-61 38-71 47-61 45-62 ever was later. Decedents for whom no death certificate ;!', was obtained are included in the causes SMR, but not i n calculating calculation of cause-specific the allresults. Results There were 21,314 persons eligible for inclusion in the study cohort. Those person of unknown race (n=3441 or sex (n= 28) were assumed to be white and male. This report i s restricted to the 19,077 white males since they made up 90% of the total cohort and 94% of the deaths. Of these, 14,609 (76.6%) were alive as of Dec. 31, 1977, 4,024 (21.1%) were deceased, and 444 (2.3%) had vital status unknown. Death certificates were obtained for all but 152 (3.8%)of the decedents. Of those alive at the study end date, 46% were still active and more than 25% were retired. One third of the total cohort and three fourths of those who died before the end of the study period were first employed before 1940. More than half of the cohort members and three fourths of those who died were ernployed for 20 years or more. There were 4,024 deaths observed and 5,331.8 expected, giving a significantly reduced SMR of 75 (Table). Most striking is the statistically significant deficit seen for every major cause of death category, including all malignant neoplasms (SMR =751, cancer of the digestive organs (SMR=70), cancer of the lung (SMR=59), metabolic diseases (SMR=78), diabetes (SMR=80), diseases of the nervous system (SMR=81), vascular lesions of the central nervous system (SMR =791, arteriosclerotic heart disease (SMR =81),all respiratory diseases (SMR = 52),all diseases of the digestive system (SMR=56), and ail external causes of death (SMR=54). There are a few causes of death for which the SMR i s -greater than 100, zthough none or m e increases IS sienif- icant. 17WQtnn3 h i (~148) i s for benign and unspecified neoplasms (20 deaths observed and I f 5 cxpected). Thir- 446 Texaco Mortality Study/ Divine et al teen of these were brain tumors (9.0 expected; SMR=IM). The SMR for cancer of the brain and CNS was slightly 3- elevated at 111. Other causes of death for which the SMR was elevated are cancer of the pancreas (SMR=107), Hodgkin's disease (SMR=108), M-IR = 1181,and cancer of other lymphatic tissue (SMR=115). Discussion This study of white male employees of Texaco refinery, research, and petrochemical facilities shows large deficijs for all the maior causes of death. The 'study covers more than 19,000 men during a 31-year period of observation with 358,029 person-years of observation. Although an overall SMR less than 100 is expected because of the "healthy worker effect," the SMR of 75 for all causes is lower than i s usually seen in published reports of petro- leum workers studies of this size and length of follow- up49, with the exception of the refinery workers study by Gaffey et al,a which had only 10 years of follow-up. Several factors may have favorably influenced the over- all SMR. New Texaco employees are required to pass a preemployment physical exam'ination, although any se- lection effect from this should not extend beyond the first few years of employment. While it was thought that ex- cluding those employed less than five years might have lowered some SMRs or obscured some excess causes of death, the analysis of workers employed one year or more at Texaco's largest refinery showed SMRs slightly lower than those for workers employed five years or more, with similar patterns of death for both groups. Many of the categories with large deficits are causes for which mortality rates have declined considerably, e.g., parasitic and infectious diseases (SMR= 27) and heart dis- ease (SMR=81). One factor affecting this is that wage and health care benefits provide Texaco employees with a comfortable standard of living and access to quality med- ical care. Those causes of death with SMRs above 100, in contrast, tend to be ones with high case fatality rates and short average duration, for which access to medical care . would make little difference. In addition, the healthyworker effect is relatively weak for neoplasms. There are a few Wpes of cancer for which SMRs are greater than 100. These are cancer of the pancreas, cancer o f t h e brain, leukemia, other lymphatic neoplasms, and benign neoplasms. Q a c c - r r a i i w q h a s &Q in particular, have been associated with refinery employment,z.s.7 the SMRs o b s e r v d in this studv are much l n w than those' seen in other studies, are elevated less than IO%, and reflect excesses of fewer than five deaths. -However. d d 'u'ts for these causes were s u Tex- a% cohort. Recent animal studies have associated expo- sure to gasoline with an increased risk of kidney cancer,?z and one refinery worker cohort study has shown an ele- vated SMR for kidney cancer'; however, this study shows no indication of an excess risk (SMR=96). The low SMR for cancer of the lung (SMR=59) is particularly striking and may be attributed in part to the nonsmoking rules in effect throughout the plants. In summary, this study has shown a favorable mort4ity experience for refinery, research, and petrochepical at lexaco Inc. Significant deficits were observed -foFmost causes of death, even some that were found,to &Ibe elevated i n other studies of petroleum workers. significant increases were seen. Further analyses of the elevatea causes ot death are in .prog-ress, as are analyses of mortality patterns for work area subcohorts. Acknowledgment Health departments of various states, including the state of New Jersey, cooperated in providing copies of death certificates for deceased members of the cohort. References 1. Blot WJ, Brinton LA, Fraumeni IF, et al: Cancer mortality in U.S. counties with petroleum industries. Science 198:Sl-53,1977. 2. Thomas TL, Decoufle P, Moure-ErasoR: Mortality among workers employed in petroleum refining and petrochemical plants. ) Occup Med 22:97-103, 1980. 3. Hank NM, Stavraky KM, Fowler IL: Cancer mortality in oil refinery workers. ) Occup Med 21:167-174, 1979. 4. Rushton L, Alderson MR: An epidemiological survey of eight oil refineries in Britain. Br I h d Med 38:225-234,1981. 5. Theriault C . Coulet I: A mortality study of oil refinery workers. Occup Med 21:367-370.1979. 6. Thomas TL, Waxweiler RI, Moure-Eraso R, et al: Mortality pat- terns among workers in three Texas oil refineries. / Occup Med 24:135- 141,1982. 7. Hanis NM, Holmes TM, Shallenberger LC, et al: Epidemiologic - study of refinery and chemical plant workers. ) Occup Med 24:203- 212,1982. 8. Caffey W, Weaver NK. Tabershaw IPA: Mortality Study of Pe- troleum Refinery Workers. Washington, D.C.: The American Petroleum Institute, 1974. 9.Wen CP, Tsai SP, McClellan WA, et al: Long-term mortality study of oil refinery workers: I. Mortality of hourly and salaried workers. Am ) Epiderniol 118:52642,1983. 10. Monson RR: Analysis of relative survival and proportional mor- tality. Cornput Biomed Res 7:325-332, 1972. 11. Cottlieb MS: Lung cancer and the petroleum industry in Loui- siana. / Occup Med 22384-388,1980. 12. MacFarland HN: Chronic gasoline toxicity, in MacFarland HN, Holdsworth CE, MacCregor IA. et a1 (Eds.): Proceedingsof the Symposium The Toxicology 01 Petroleum Hydrocarbons. American Petro- leum Institute, Washington, D.C.: 1982. Journal of Occupational MedicinelVol. 27. No. G/June 1985 447