Document wrErYDyynxXpQdJemZ7ayJYLJ

DOW CHEMICAL U.S.A. July 25, 1985 J. H. Triebwasser, H.D. Medical Department 607 Building cc: J. H. Venable, M.D. J. H. Saunders, M.D. G. G. Bond MIOLANO. MICHIGAN 48640 Received L&s*-L L'i r'i-Ju V P, RE: EPIDEHI0L06Y REPORTS RELATED TO ASBESTOS A short while ago I was contacted by Mark Penley, an outside attorney representing Dow Texas Division In litigation involving asbestos. He asked for Information on any human health studies related to asbestos that were conducted among Dow employees. Going through our records, we found two that had been conducted by Jerry Ott back in the early 70's. One was on Texas Division insulators. A copy of the report has been sent to Jim Saunders for him to discuss with legal. A copy of the second is enclosed. This study, dated 10/21/70, and entitled, "A Statistical Evaluation of Respiratory System Indicators Among Pipe Coverers' evaluated a select group of Michigan Division employees. After your review, please forward it to Jim Saunders. Ralpn k. coox, M.D. Director of Epidemiology Epidemiology, H&ES 1803 Building Midland, MI 48674 RRC/aag ST0000072' AN OPERATING UNIT OF THE DOW CHEMICAL COMPANY RESTRICTED FOR USE within THE OOW CHEMICAL COMPANY ==Qualitv= Performance VAjnfc Mjtv Ai La. .% A STATISTICAL EVALUATION OF RESPIRATORY SYSTEM INDICATORS AMONG PIPE COVERERS 10-21-70 MGO tt ST0000073 INTRODUCTION This report presents statistical findings developed from an epidemiologic study of pipe coverers. The report does not include a review of literature on the subject or a medical interpretation of the results. In the location under study, the job of pipe coverer has existed since 1910. A list of 173 men who have held this job was prepared from company personnel records. Virtually all men who worked on the job for at least a year are included in the list, as well as most of the men who worked less than a year. As of January 1970, the status of the 17 3 men was as follows: Still Working For Company 130 Active Pipe Coverers 94 No Longer Pipe Coverers 36 Quit or ReleasedFrom Company 18 Retired "t-2* | \ Deceased '1414 Within the identified exposed-to-risk population, the relationship between time-on- job and health indicators reflective of the well-being of respiratory function was investigated. The health indices examined in this study include (1) the mortality rate for cancer of the respiratory system (based on company insurance records, 1940-1970; (2) the incidence of morbidity episodes involving diseases of the respir atory system (based on company insurance records, September 1969-August 1970); and, (3) vitalometer measurements (derived from a multiphasic health screening program, 1967-1970). METHODOLOGY Selection Of Exposed-To-Riak Population And Controls Pipe coverers were identified through personnel lists prepared on a monthly basis by the company. The personnel lists are ordered by department and job classifi cation within department and are retained as far back as the 1920's. However, only the January listings are retained beyond ten years. Since pipe coverers tend to remain on the job for a long period of time, this method is adequate for identifying the exposed-to-risk population. Two sets of controls were utilized in this study. The first set of controls consisted of the total plant population and the second consisted of pipe fitters. While the total plant population was selected for convenience, a probability sample of the pipe fitter population was selected because these men had jobs closely related to the pipe coverers except for exposure to asbestos. The pipe fitters were identified by the same method as was used to identify the pipe coverers. Because there are many more pipe fitters than coverers, - a thirty percent sample was drawn by terminal digit sampling of company identification numbers. Method of Morbidity Analysis For the purpose of this study, a morbidity episode is an absence characterized by the filing of a proper accident and sickness benefits claim covering a continuous period of absence from work. The claim includes a physician's certification of the medical cause of the absence. In most cases, the morbidity episode must extend beyond seven calendar days before a record of the event is created. The program, as such, is available to hourly employees of the company. The expected number of disability days shown in'Tables 1 and 2 are based on a five year age grouping of data on over 5, 000 hourly employees. Method of Vitalometer Analysis The company's multiphasic screening program, offered on a voluntary basis, calls for F.E.V. Total and F.E. V. 1 Sec measurements to be recorded for each partici pant. A Collins Vitalometer produces the tracings which are digitized by a tech nician. For analysis purposes, the most positive of three repeated tracings for each individual is computerized. A regression equation was developed from the total screened population to adjust for height and age. Monthly comparison of measured results has shown that, over the three years of the program, consistent readings have been obtained. Using data generated through a multiphasic screening program has the advantage that neither the subject nor the technician is aware of uses to which the results might be put. Participation in the health inventory program was about 67% during the first cycle of the program. By combining first and second cycles, vitalometer readings were obtained for 101 men in the pipe coverer population. Several selection factors which could bias somewhat the findings of this study should be noted. First, it was not feasible to follow up on the 18 employees who left the company; two of these men were known to have left because of poor health. Secondly, a morbidity study covering a period two years following the first cycle of the multiphasic screening program revealed that participants in the program experience fewer illness-absence episodes than non-participants. The study did not enable us to determine the reasons for this difference. ST0000074 - 3- While the same selection factors apply to the control populations, caution must be exercised in interpreting results because of these unknowns. Method of Mortality Analysis The mortality analysis is based on copies of death certificates received by the com pany Group Insurance Department as proof of death. As mentioned previously, individuals released from the company, excluding retirees, will be lost to a mor tality study based on insurance records. The two control groups referred to in Table 6 were studied over a more recent time period than the pipe coverers, even though the first twenty years following initial placement on the job was not accumu lated as part of the exposure-to-risk years for pipe coverers. However, since the mortality rate due to cancer of the respiratory system has been increasing over the years, this comparison should error slightly on the conservative side. The mortality rates for the three groups were calculated on an age-adjusted basis. Smoking History A smoking history collected as part of the multiphasic screening program was not judged as satisfactory for use in this study. The set of questions concerning smoking history has been restructured and appears to be producing results that can be useful in the future. The lack of smoking history does impose considerable limitations on the conclusions that can be drawn from the study. - RESULTS Table 1 shows that while no pipe fitter employment groups differ from the total plant in disability days due to respiratory disease, there are differences among the pipe coverers. The largest difference occurs among pipe coverers with 10 years or more of continuous employment on the job. These differences, however, are not fully reflected in total disability days. In Table 2, the number of episodes involving respiratory disease are compared. Based on a poisson approximation test, significant differences between observed and expected episodes were found for three employment groups among the pipe coverers and for no pipe fitter groups. However, the significant differences in the continuously employed group might be expected to carry over to the total group. Vitalometer Analysis The readings shown in Table 3 are height and age corrected. Only after ten years of employment do significant differences between corresponding groups of pipe coverers and fitters appear. The prior-to-employment group consists of men who worked at other jobs during the first cycle of the multiphasic screening pro gram and later became coverers or fitters. A non-linear regression equation ST0000075 -4- it i' was developed for F.E.V. Total and F.E. V. 1 Sec using years since first exposure as a pipe coverer for the independent variable. The regression lines, along with the scatter plot of individual readings, are shown in Figure I through Figure IV for both fitters and coverers. Mortality Analysis All causes of death among pipe coverers up to 1970 are listed in Table 5. These deaths are categorized by interval between initial employment as a pipe coverer and death, and by length of employment as a pipe coverer. An excess of total deaths and respiratory cancer deaths among pipe coverers, as compared to two other groups, is indicated in Table 6. The number of observations is quite small. In addition, two of the men dying from respiratory cancer also worked with lead arsenate. SUMMARY The data presented in this study were derived only from ongoing routine functions of the company Medical Department. The investigation of vitalometer readings, morbidity episodes due to respiratory disease, and mortality due to respiratory cancer, indicated that pipe coverers performed less well than did the comparison groups. There are two important limitations of the study aside from the size of the exposedto-risk population. First, no smoking history was obtained. Second, follow-back of individuals no longer with the company was not undertaken. ST0000076 10-13-70 MGOtt Table 1. DISABILITY DAYS{1) PER PERSON PER YEAR AMONG PIPE FITTERS AND PIPE COVERERS ACCORDING TO LENGTH OF EMPLOYMENT (AGE CORRECTED). Employment as a Pipe Fitter Pipe Fitters N amber, of Men1 ' Total Disability Days ,, Observed Expected Disability Days Due To Respiratory Disease Observed Expected Continuous <10 Years 56. 3 10 Years or more 34.5 Both Continuous and Non-Continuous$ <10 Years 58.3 10 Year* or more 67.5 1 5.8 8.4 9.3 12.6 6.7 12. 1 8. 5 12. 2 0.8 1.7 0.8 1.4 1.4 1.9 1.6 1.9 Employment as a Pipe Coverer Continuous <10 Years 10 Years or more Both Continuous and Non-Continuous < 10 Years 10 Years or more Pipe Coverers Number of Men Total Disability Days Observed Expected Ui6abiiity Days Due To Respiratory Disease Observed Expected 57.0 33.7 8.0 13.8 8.8 13.0 2. 1 7.4 1.5 1.9 70. 1 57.0 12.6 8. 5 4.7 1.4 11.9 12.7 5.0 1. 9 (1) Disability days include non-working days. The analysis period is frorr. September 1969 to September 1970. (2) Number of men take on fractional values because some men may have retired or quit the company within the study period. (3) Expected values are calculated from the total plant experience and are age-corrected. (4) This category includes men who may have worked for several years as a fitter or coverer and then changed jobs within the company. ST0000077 10-13-70 MGOtt Table 2. DISABILITY EPISODES DUE TO RESPIRATORY DISEASE AMONG PIPE FITTERS AND PIPE COVERERS. -- Employment Continuous < 10 Years 10 Years or more Both Continuous ind Non-Continuous < 10 Years 10 Years or more Number of Episodes Pipe Coverer Pipe Fitter Observed Expected Observed Expected 9 14** 5.4 3.7 5 5. 1 2 3.7 16+* j 14** 6, 4 6.2 5 5. 3 5 7.3 Significant at .01 level. There were no statistical differences between expected and observed episodes among pipe fitters. ST0000078 10-13-70 MGOtt Table 3. VITALOMETER READINGS FOR PIPE COVERERS AND PIPE FITTERS BY EMPLOYMENT CATEGORY BASED ON HEALTH INVENTORIES. Employment Category Total Prior to Employment 1 Continuous Employment ^10 Years 10 Years or more Total Employment^ <10 Years 10 Years or more Pioe Cover srs F.E.V. F.E.V. Pine Fitte ts F.E.V. F.E.V. Nbr. Total 1 Sec. Nbr. Total 1 Sec. 101 3.87 3.31 Ill 4. 13 3.60 20 3.90 3. 38 14 4.03 3.67 21 4. 17 3. 58 24 4. 14 30 3.76** 3.28 34 4. 12 3.62 3.51 27 4. 10 3.61 27 4. 14 54 3.75** 3.23** 70 4. 15 3.63 3.57 : (I) Years are calculated from date of first exposure regardless of the duration of employment. Mean value for Pipe Coverers significantly different than mean value for Pipe Fitters at the .01 level (Student's -t Test) ST0000079 FE. V. +of*l 08000001S Scoffer PloF'or F >V. fo-fqI rtaJi'n^r for- SI pip* cov?yers by yms y/hcc */rjt employ runt ** a co\/<r<r (aje jkJ toy r e ctf j). 5 0V . 4-0- - - -- l 3.0- .. V. "To^alf a.o4 -i- -I__________ I__________I--------------- 1--------------- 1----------------1--------------- 1--------------- 1--------------- 1__________ I__________ I__________ L_ j 4- b i? lO li 14 16 IS JO -u a If 2b Yeayf 5-rcc F *Vr f e mo y >v f oh job - _______ F/juri Hi, A* qHer FIof of .V. i sec_re.aJ>'j s for __ _P itjfrf by yJcaayt--'*-y j. ii\c t_ P'.'ri't < h*plo\jjntn.ps a.JjLnjrrJLtg a*ci car? ), J.Of K H.V. i sec. .,,V. I s rc ....... . ... F.^ureU- Scatisv Plot of F.U f Sec readies -fov ?/ p i CL Cohere rs by yeqrs 5i'nce. fiYsi' e *ploy m? n"f of a covered Ca^t Ke^ki cor r ol) . 5.0 f ST000008 10 4 5 .i X. H- fe . Vfarr i s iwr ? - i______ I_______________I Il_ _ 10 )i 14 16 IS JO First f rqCh.t-Oh..iaJb. _i-------------- 1_ 46 4 Table 5. CAUSES OF DEATH BY YEARS WORKED AS PIPE COVERER AND BY INTERVAL BETWEEN INITIAL EMPLOYMENT AS A PIPE COVERED AND DEATH. (BASED ON DEATHS REPORTED THROUGH SEPTEMBER 1972) rveviaeu aj./ , ,, MGOtt i Interval Between Initial Employment As Pipe Coverer And Death .0-9 Years _ 10 - 19 Years 20 - 29 Years 30 - 39 Years Yrs. Cause of Death Yrs. Cause of Death Yrs. Cause of Death Yrs. Cause of Death 2 Ca. Resp.* 14 6~ ~ Myocardial _In fartion____ Suicide 29 27 24 22 16 12~ 6 "l" <1 Ca^ Resp^___ Ca. Resp. Post Op. Ca. Resp. Fall_A Work_ Aortic & Mitral _Valve_Disea&e Ca. Pancreas Coronary _0cc1usion_ _ Ca^ Res___ Myocardial In farction (Fibrous adhes ions of apex of left lung) *** 31 30" 21 _7_ Ca_j_ Resp^____ Cau_ jisophaU Arteriosclerotic Renal Disease Ca^_ Resp^*^____ *Had previously spent 1-1/2 years in Fb Arsenate 19 years prior to death. **Had previously spent 3 months in Pb Arsenate 29 years prior to death. ***Had previously spent 1 year in Pb Arsenate 27 years prior to death 1 Mesothelioma not included in above population--Died 1970--Worked grinding asbestos pipe cover to make "cement" for about 1 year (1945?). Table 6. OBSERVED DEATHS FOR PIPE COVERERS BEGINNING AT 20 YEARS AFTER INITIAL EMPLOYMENT VS. EXPECTED DEATHS BASED ON TOTAL PLANT POPULATION AND U.S. POPULATION MORTALITY RATES (ADJUSTED FOR AGE DIFFERENCES). OO H O O o o o oo ro Total Deaths Ca. Resp. Other Ca. Pipe Coverers* 1930 - 1969 13 6 2 Total Plant 1954 - 1969 5.9 .6 .9 U.S. Population 1966 7.6 .5 1.0 *0ver 91 percent of the exposed-to-risk years occurred after 1953.