Document Vjq8YNOZ0ZEZVoyQ8XaGk2KKj

% Brief Report 37 fio CO 000246 Update to Vinyl Chloride Mortality Study The mortality experience of 593 Dow Michigan Divi sion employees potentially exposed to vinyl chloride was recently updated through 198S. An earlier study evaluated this group for the time period 1942 through 1973 and found an excess of total malignancies among the subgroup considered to have the highest exposure.1 However, during the additional period of follow-up (1974 to 1982), a deficit of malignant neoplasms was observed for this subgroup. During the 9 years of additional follow-up, the total deaths in the study group increased by G3 (to 155) and the person-years by 4,234 (to 17,114): The study's primary focus was directed at cancers of the liver (including angiosarcoma), biliary tract, lung, and brain, and to emphysema because of previous reports linking these conditions to vinyl chloride exposure in some work forces.2'3 No deaths from angiosarcoma were found and there were no statistically significant excesses for any of the other conditions of interest. Only those employees identified for the original study were included in the recent investigation and their work histories and exposures were updated through 1977 to ensure a minimum 5-year induction latency period. Con sistent with past practice, separate analyses were con ducted first including and then excluding the subset of employees with prior, competing exposures to arsenic insecticides.'* Cause-specific mortality among the study group was contrasted both with expected levels based on age- and era-specific mortality rates for US white men, and also with the mortality experience of 24,410 other male employees from this company location who were not exposed to vinyl chloride or arsenic. The comparison with US men is shown in the Table. Total malignant neoplasms were less than expected in the updated follow-up period (1974 to 1982), 12 v 16.3 and for the total follow-up period (1942 to 1982), 27 v 31.7. There were no statistically significant excesses for any of the diseases of interest. Similar results were seen for the comparison with other employees from this com pany location. One death from liver cancer occurred in the study group (0.6 expected). The pathology and autopsy re ports indicated that it was an intrahepatic bile duct carcinoma. There were two deaths from brain cancer (1.2 expected), one of which occurred less than 5 years after first exposure to vinyl chloride. Both individuals had only short-term exposure in jobs categorized as less than 200 ppm time-weighted average (TWA). There were six deaths from emphysema or chronic obstructive pulmonary disease (approximately 5 ex pected). None of these individuals worked in areas where there was a potential for exposure to polyvinyl chloride dust. An increased risk of lung cancer was not found (stand ardized mortality ratio = 89) and the study was capable of ruling out more than a 60% increase with 95% certainty. The lack of an association with lung cancer is consistent with the findings from the majority of other studies, especially those with the greatest statistical power to detect an excess.8 To examine for a dose-response relationship, subjects were allocated to one of four intensity-of-exposure cat egories (undetermined, less than 25 ppm TWA, 25 to 200 ppm TWA, and 200+ ppm TWA) based on their highest rated job assignment held for at least 1 month. During the updated follow-up period (1974 to 1982), a deficit of total cancer occurred in the highest exposure category (3 observed v 5.4 expected); however, for the entire follow-up period this subgroup experienced an excess which was confined principally to the men with at least 5 years of exposure above 200 ppm (7 observed v 2.8 expected). As was noted in the original study,1 there was no predominant tumor site nor was there a unique histologic type among this subgroup, weakening any interpretation of a causal link with vinyl chloride. Wendy S. Dahar, MPH Gregory G. Bond, PhD, MPH Blsie A. McLaren, RN Fred L. Sabel, MS Thomas E. Lipps, MD Ralph R. Cook, MD, MPH The Dow Chemical Company Epidemiology Health and Environmental Sciences 1803 Building Midland, MI 48674 648 Update to Vinyl Chloride Mortality Study/Dahar et al I TABLE Observed and Expected Deaths for Selected Causes Exduding Employees with Prior Exposure to Arsenic Insecticides Cause of Death (ICD-8) 1942-1973 Obs Exp* Period of Follow-up 1974-1982 Obs Exp Obs 1942-1982 Exp SMRt All causes 80 84.9 50 67.0 130 All cancers (140-209) 15 15.4 12 16.3 27 Digestive system cancer (150-159) 6 4.4 3 4.1 9 Liver cancer (155,156) 0 0.3 1 0.3 1 Respiratory system cancer (160-163) 4 4.9 6 6.4 10 Brain cancer (191.192) 1 0.6 1 0.5 2 All circulatory diseases (390-458) 38 41.1 27 34.3 65 All nonmalignant respiratory diseases (460-519) 6 4.2 3 4.4 9 All accidents (E800-E949) 7 8.4 1 2.5 8 * Expected numbers are based on calendar time and age-specific mortality rates of US white men. t Standardized mortality ratio; observed divided by expected number of deaths x 100, i Cl, confidence interval of Obs/Exp, Not calculated when expected number of deaths fewer than 5. 151.9 31.7 8.5 0.6 11.3 1.1 75.4 8.6 10.9 86 85 106 -- 89 --S 86 104 74 95% Clt 72-102 56-124 48-201 4-899 42-163 23-682 67-110 48-198 32-144 References 1. Ott MG, Langner RR, Holder BB: Vinyl chloride exposure in a controlled industrial environment. Arch Environ Health 1975;30:333339. 2. Wong O, Whorton MD, Ragland D, et al: An update of an epidemiologic study of vinyl chloride workers. 1942-1982. Prepared for the Chemical Manufacturer'* Association. October 17, 1986. 3. Purchase IFH, Stafford J, Paddle GM: Vinyl chloride: An assessment of the risk of occupational exposure. Food Chem Toxicol 1987;25:187-202. 4. Ott MG, Holder BB, Gordon HL: Respiratory cancer and oc* cupational exposure to arsenic&ls. Arch Environ Health 1974:29:250255. 5. Bond GG, McLaren EA. Cartmill JB, et al: Cause specific mortality among male chemical workers. Am J Ind Med 1987;12:S53~ 383. 6. Beaumont JJ, Breslow NE: Power consideration* in epidemio logic studies of vinyl chloride workers. Am J Epidemiol 198l;l 14:725734, R&S 000247 Journal of Occupational Medicine/Volume 30 No. 8/August 1988 649