Document Gz6pr3BoeZ3ZX6E7JJedp9Bwr

J. L. h'elscn -- 3iii waa rsad to Denaia folit* of tbs louiaville Cicsa yesterday ia response to n <*\ery about the ataber of eepioyeea currently at hes and their coepenfiatott August 74, 1974 V. T. Ihaka STATEMENT FOR USE IX R6PLV TO QUERY FROM DEMMIS POLITE It Is our practice to remove employees with liver abnormalities fro* their jobs when our plant physician feels it is warranted, Tn- some cases, these employees are sieved to other^work. In other cases they are sent hose until further diagnostic study can be completed or the abnormality is corrected. The number of such employees has been small. None of these employees sent hotoe have been laid off. They are receiving full benefits under our programs. -0- Coplea to: A. Vlttone R. D* Scott J# L. Nelson E. W. Harrington H. Waltemate B. M. G, Zwicker G. Pow W. J. Wilcox P. J. Weaver R B. Downey E. B. Osborne R* P, Kenney - A. L. Hatfield - C. R. Flynn K. Greene 20397001 BFG03247 TO B. M. G. Zvicker OM J. C. Schaap A. M. Falrlle PlCkO POINT ON AKNON OCp.NTMKnT * 01041. NO. Cleveland Cleveland Comments on Peters and Uonson and NIOSH Mortality Tables -- Proportional vs. Actual Mortality Analysis O.r* >OUft LCTTIft o.ts thi. borrN August 22. 1974 SUMMARY: Proportional and actual mortality analyses are two methods commonly used to construct mortality tables. The proportional mortality table Is useful In determining whether a population has an abnormal distribution of deaths amopg various diseases, but may be misleading as to whether the death rate of a specific disease Is actually abnormal. The actual mortality table permits this latter determination. Peters and Monson use proportional mortality analysis to show that rates of brain, liver, lung, and total cancers are abnormally high in the Louisville and Calvert City plants mortality data. An actual mortality analysis by BFG indicates that only brain and liver are significantly in excess. Data from a NIOSH study of the Louisville plant indicates that brain, liver, and total cancer rates are again high. However, the method of mortality analy sis is not given. DISCUSSION: Dr. John M. Peters of Harvard University testified before OSHA on June 27, 1974. He and Dr. Richard Monson obtained data on 161 deceased workers from the Louisville and Calvert City BFG plants. They constructed a mortality table based on this data and the age distribution of the plants' employees (Table 1). Their major findings indicated (1) a 502 excess of total cancer deaths, (2) a 602 excess of lung cancer, and (3) a 3202 excess of brain cancer. Liver cancer cases were ten times that expected. The above conclusions are based on a proportional mortality analysis. In addition, a study by NIOSH has indicated an excess of cancer deaths among 86 deceased employees of the Louisville plant. 1 This data could also have been analyzed on a proportional mortality basis, but at this time we are not certain of this. The above conclusions are not consistent with those found in the TabershavCooper MCA study, nor with Table D of TCA's addendum to the BFG study. The discrepancy is apparently caused by the differences between the numbers of 20398001 1. "Louisville VC Study" to A. Vittone from M. N. Johnson ira nit mv, ti/n uTM. in w.a.A. BFG03248 5. M. G. Zvicker August 22, 1974 Page 2 expected deaths calculated in the proportional' mortality analysis used above, and the actual mortality analysis method employed by TcA.l The numbers of expected deaths in the actual mortality analysis are cal culated from the observed death rates of the U.S. male population having an Identical age distribution. An expectation of, say, 40 cancer deaths In a plant's employee population means that 40 people will, on the average, have died of cancer, regardless of the rates of other diseases. Numbers of expected deaths In a proportional mortality analysis are found by computing the proportion of deaths In the age adjusted U.S. male popula tion, and multiplying these proportions by the total number of observed worker deaths. An expectation of, say, 40 cancer deaths in a proportional mortality table containing 200 total deaths would indicate a 20% proportion of cancer deaths in the age adjusted U.S. male population. It is our opinion that an actual mortality analysis reflects true relation ships between observed and expected death rates while the proportional mortality analysis can lead to serious distortions. The differences be tween these two analyses can be more easily seen in the following hypothe tical exanple. t Suppose 20% of an age adjusted U.S. male population will, on the average, die of cancer, 60% of heart disease, and 20% of other causes. Also assume that the expected number of deaths calculated by the actual mortality analy sis Is 200. Then the expectations of actual mortality are: Disease Cancer Heart Other Total Expected Number of Deaths 40 120 40 200 If 40, 120, and 40 plant people had actually died of cancer, heart disease, and other causes, respectively, the plant population would be considered "normal." However, suppose only 80 had died of heart disease, but still 40 of cancer and 40 of other causes. The actual mortality table would be: Disease Cancer Heart Other Total Observed 40 80 40 160 Expected 40 120 40 200 1. The term "actual mortality analysis" refers to the method used by TCA in determining the Standardized Mortality Ratio (SMR). BFG03249 TT 20398002 B. M. G. Zwicker August 22, 1974 Page 3 Th rate of heart disease Is 332 less than normal. Cancer and other diseases occur at normal rates. The overall death rate is 202 less than normal. The proportional mortality table does not lead to the same conclusion. Multiplying the respective proportions (.2, .6, .2) by the total number of observed deaths (160), the proportional mortality table Is: Disease Cancer Heart Other Total Observed 40 80 40 160 Expected 32 96 32 160 ' diseases are now Indicated as 252 in excess Heart disease is 17Z less than normal. This apparent increase in the rate of cancer is actually due to the lower Incidence of heart disease. The Peters and Monson table is a proportional mortality table. Much of the cancer excess indicated in their Table 1 is apparently due to the lower Incidence of heart disease found at Louisville and perhaps also at Calvert City. The MCA study and the BF6 addendum indicate that vinyl chloride workers in general and also Louisville employees have significantly lower death rates than comparable age adjusted U.S. male populations. Taking this lower mortality into account, the Peters and Monson table can be corrected to express actual rather than proportional mortality death rates.1 This correction is only approximate since it is based just on the Louisville workers included in Table D of the addendum, and not on the combined Louis ville and Calvert City plant populations. The corrected data are displayed in Table 2. Major conclusions are: (1) Total deaths due to all cancers are not significantly higher than expected (41 actual vs. 35.1 expected). (2) Liver and biliary cancers are significantly in excess (8 actual vs. 1.0 expected) (3) Cancer of the brain is significantly in excess (5 actual vs. 1.5 expected). (4) Cardiovascular and renal diseases are significantly lower than expec ted (74 actual vs. 98.1 expected). 20398003 1 Corrected by multiplying each expected number of deaths in the proportional mortality table by 1.257 * expected number of deaths among Louisville employees with El 1.1-3.0 actual number of deaths among Louisville FT 1 1-3.0 108.17 BFG03250 T' T B. M. G. Zwicker August 22, 1974 Page 4 The NIOSH data may have also been analyzed on a proportional mortality basis. If so, the same correction factor (1.257) could be applied: Cause of Death All Malignancies Liver Malignancy Brain Malignancy Leukemia and Related Malignancy All Others PROPORTIONAL MORTALITY Observed Expected Obs/Exp 26 16.3 1.6 * 6 .4 15.0 * 3 .57 5.3 * 3 1.6 1.9 14 13.69 1.0 ACTUAL MORTALITY Observed Expected Obs/Exp 26 20.5 1.3 6 .5 12.0 * 3 .7 4.3 * 3 2.0 1.5 14 17.2 0.8 * Significant with 95X confidence The actual mortality analysis indicates that liver and brain malignancies are significantly in excess. The proportional mortality analysis also indi cates (incorrectly) that the "all malignancy" category is abnormally high. 20398004 A. M. Fairlie AMF/JCS:cls cc: A. Vittone R. D. Scott J. L. Nelson W. J. Wilcox , W. C. Becker M. N. Johnson R. W. Strassburg E. B. Katzenmeyer, Jr. E. W. Harrington 0. F. Beckmeyer R. M. Kreager - a. L. Schultz R. L. Bowles T' T BFG03251 TABLE 1 OBSERVED AND EXPECTED DEATHS IN VINYL CHLORIDE WORKERS a ICD Number ^ --- 140-205 150-159 155 162,163 193 200-205 -- 330-334 400-468 800-998 960-969 -- Cause of Death All All cancer Digestive Liver & Biliary Tract Lung Brain Lymphatic & Hematopoetic Other c (2(5 Vascular Circulatory External Suicide All Other d Observed Expected Obs/Exp 161 41 13 8 13 .5 5 161.0 1.0 27.9 1.5 8.3 1.6 0.8 10 7.9 1.6 1.2 4.2 3.4 1.5 5 8 66 22 10 24 7.1 9.5 . 68.6 24.5 5.3 30.5 0.7 0.8 1.0 0.9 1.9 0.8 a. Expected numbers based on age-time specific proportional mortality rates for U.S. white males b. International Classification of Diseases, 7th Revision c. Nasopharynx - 1, prostate - 1, kidney - 1, thyroid - 1, undetermined - 1 d. Includes 2 cirrhosis (4.2 expected) BFG03252 20398005 TABLE 2 Actual Mortality Analysis Approximate Observed and Expected Deaths in Louisville and Calvert City VC1 Workers, Adjusting for Overall Death Rate of Mon-Exposed Age Specific U.S. Male Population ICD Cause of Death 140-205 150-159 155 162,163 193 200-205 330-334 400-468 330-334 400-468 800-998 960-969 All Causes All Cancer Digestive Liver and Biliary Lung Brain Lymphatic and Hematopoetic Other Cancers Cardiovascular and Renal CMS Vascular Circulatory External Suicide All Other " (Inc. 2 Cirrhosis, 5.3 Expected) Obs erved 161 41 13 8 13 5 5. 5 74 8 66 22 10 24 Expected 202.4 35.1 10.4 1.0 9.9 1.5 4.3 8.9 98.1 11.9 86.2 30.8 6.7 38.3 Obs/Exp .80 * 1.17 1.25 8.00 * 1.31 3.33 * 1.16 .56 .75 * .67 .77 * .71 1.49 .63 * 20398006 * Significant with 952 confidence BFG03253