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FILE NAME Brakes BRK DATE 1983 DOC BRK114 DOCUMENT DESCRIPTION Journal Article - Mesothelioma in Connecticut 1955-1977 Same as 82 tration pected nd the cluded itoring osteo : more , urine irinary th the Iso be Joride ormed from roach lerline arma- oride EXHIBIT Zo Betty Browning Mesothelioma in Connecticut 1955-1977 Occupational and Geographic Associations Mary Jane Teta M.P.H Hilton C. Lewinsohn M.B. B.Ch J. Wister Meigs M.D Romeo A. Vidone M.D Linda Z. Mowad R.N and John T. Flannery B.A. rs and uorine orides ation Ind cd 2 are of lurgic n and Med Med techFrom agan bride Fe and 982 bility renal 978 e Aluo- 977 arcel tions ride cs of Elin ef iche ini- ini979 sma Res ee ree bo <n All cases of malignant mesothelloma 201 and other primary malignant pleural tumors 19 reported to the Connecticut Tumor Registry from 1955 through 1977 were studied in an attempt to identify high jobs Industries and geographic locations and to estimate the risk attributable to asbestos exposure in the workplace Data were obtained from hospital records death certificates and city directories for cases case spouses and a random sample 604 of Connecticut decedents 1955-1975 Three cases involved histories of work in asbestos products manufac ture but there was no evidence of residential risk in that geographic area Relative risk RR for carpenters and cabinetmakers was 2.25 p < .05 for plumbers and pipefitters 3.87 p < .05 and for persons ever employed in the rubber industry 5.08 p < .01 Occupational exposure was indicated in 85 of the cases attributable risk AR was 36 Risk increased with greater exposure and older age AR was 81 in men aged 70 to 89 years at diagnosis Reduction of unnecessary occupational asbestos exposure remains the highest public health priority In 1980 Lewinsohn et all described mesothelioma in Connecticut from 1935 through 1977. Problems of diagnosis and ascertainment made results for the years prior to From the Yale School of Epidemiology and Public Health New Haven Conn Ms. Teta Associate in Research Connecticut Cancer Epidemiology Unit Dr. Meigs Clinical Professor of Epidemiology and Public Health and Ms. Mawad Associate in Research the Union Carbide Corporation Danbury Conn Dr. Lewinsohn Assistant Corporate Medical Director the Yale University School of Medicine Dr. Vidonc Associate Clinical Professor of Pathology and the Connecticut Tumor Registry Connecticut State Department of Health Services Hartford Mr. Flannery Director Ms. Teta is now affiliated with Union Carbide Corporation Danbury Conn Address correspondence to Union Carbide Corporation Health Safety and Environmental Affairs Dept. P2 1 Ridgebury Rd Danbury CT 06817 Ms. Teta This investigation was supported by grants 33235 and 61002 awarded by the National Cancer Institute US Department of Health and Human Services and by the Institute of Occupational Medicine and Hygiene Yale University School of Medicine 1955 of uncertain value From 1955 through 1977 the adjusted rates among males rose from about 0.19 to 100,000 and among females from 0.13 to 0.19 100,000 Bruckman et al claimed in 1977 that increases in the discase are due to the increase in the cumulative asbestos consumption and that emissions into the environment e.g. building construction demolition automobile brake linings are somehow involved as causative factors The substantial rise however in the female ratio is more consistent with occupational exposures of men at work Bruckman et al were unable to provide complete occupational histories for the 133 diagnosed cases of mesothelioma 1935-1972 drawn from the Connecticut Tumor Registry CTR on which their report was based Despite this limitation the Air Compliance Unit of the Connecticut Department of Environmental Protection has proposed an ambient air standard of 30 m measured over a day interval This proposal was based on estimated asbestos concentrations at several selected sites in Connecticut Mesothelioma is a rare disease with approximately 2.2 cases per million population expected annually The proportion of cases not associated with some form of asbestos exposure has been reported to be near .5-7 This disease may serve as a marker for unsuspected past asbestos exposure The present study was designed primarily to examine the job categories and industry titles of identified cases of malignant mesothelioma recorded in the CTR in an attempt to 1 identify job categories industries specific employers and Connecticut geographic locations that are associated with an excess risk for mesothelioma and that may also be associated with asbestos usage and 2 determine the proportion of cases involving possible exposure to asbestos in the workplace The health implications of the proposed ambient air standard make it desirable to estimate the kinds and num bers of cases that may be due to occupational asbestos exposure other as yet undetermined risk factors or possible asbestos exposure from the general environment There remain numerous unanswered questions concerning the existence of a threshold and the nature of the as- Journal of Occupational Medicine 25 No. October 1983 749 | mesothelioma response relationship.6.9 The all allowed us to approach these problems syoesty In lieu of dust measurements job and industry es ascertained for study subjects for periods up to 50 veuts were used as indicators of exposure Methodology sss mesothelioma has often been confused with other ma grant tumors an anatornic pathology review of all reported case reported to the CTR between 1955 and 1977 was wrasiinen, aves 7 cal ser vw Histologic materia along with gross autopsy reports was submitted to one of us R.A.V. No personal identifiers or occupational data we oude Although the final results of this review will be 7eD she separately specific findings will be discussed " context of the present report The CTR registered 196 cases of primary malignant om during the years 1955 to 1977 inclusive W the exception of the Veterans Administration VA soso ibs in Connecticut it is mandatory for hospitals to cone agnosed malignant neoplasms to the central meg A review of all autopsy records from the larger of the two VA nospitals in the state from 1955 through 1977 \ ese ese five additional cases of mesothelioma bringing the tota tota number to 201. This included 137 cases with site nore 29 with site peritoneum and 35 of other or unKnown sites Concerns about diagnostic sensitivity promptthe inclusion of 19 cases reported as pleural tumors other than mesothelioma during the same year period These contems were justified by the slide review tha genated genated several cases of mesothelioma in this group The teta case study population size was 220 Table ) Medical demographic and occupational data have been cted for these 220 cases Similar information was gathered by Roush et al10 for a computer ran- ger mple of 604 decedents 1955-1975 aged 20 to 98 Table 1 - Sex Age and Diagnostic Classification of 201 Cases of Malignant Mesothelioma and 19 Other Pleural Tumors Diagnosed in Connecticut 1955-1977 Diagnosis Pleursi mesothelioma Pleural tumor other than mesothelioma Peroneal Peroneal mesothelioma Mesothelioma at other sites and 20 unknown sites Males Females Total 100 11 37 137 . B 19 18 11 29 21 14 35 Mean Aget 63 63 59 54 Tatn 150 70 220 61 World Health Organization 1976 as originally recorded by 073 A diagnosis 750 years who provided a control group These controls were drawn without stratification of any kind from the death certificate files of the Division of Health Statistics of the Connecticut State Department of Health Services CSDHS Death certificates DCs provided demographic data and usual occupation directories CDs ment histories 1 date of diagnosis for study subjects at time of death City were searched for residential and employ- 10 20 25 30 40 and 50 years prior to or death provided that the subject was at least 20 years old at the time The Price and Lee City Directories which are available for about two thirds of Connecticut towns from 1890 to 1980 have a target population of 92 of the adult males in the state A similar occupational history and cancer search was conducted for all spouses n = 193 of the 220 cases to explore the possi bilities for domestic exposure that may have originated in the workplace The three 1970 U.S. Census industrial and occupational codes were assigned to the employment informa- tion ascertained Industrial coding was determined on the basis of product descriptions for each employer which were found in the manufacturing directories of Connecticut published by the State Department of Labor and in the Price and Lee directories for nonmanufacturing industries The study population for occupational analysis was re- stricted to males over 30 years of age at death or diagnosis large proportion of females 46 cases 31 controls had no known work history Although nonoccupational etiologies may be a possibility the absence of reliable occupational data for females prevented a formal analysis of their occupational asbestos exposure Since all cases were born after 1874 controls born prior to 1875 were ex- cluded There remained 611 male subjects for the occupational analysis 136 mesothelioma cases 11 cases ofpleural tumors other than mesothelioma and 464 controls The control ratio was approximately 3 Seven cases included in the analysis were those of individuals who were alive at the time of the data collection period 1978 Study subjects were first compared on the basis of whether they had ever worked in selected jobs orindus- tries with known potential for occupational asbestos ex- posure or for which there were sufficient numbers to be informative Formal statistical comparisons were made for seven job categories engineers brickmasons and stone- masons cabinetmakers and carpenters electricians fore- men painters construction and maintenance workers and plumbers and pipefitters and for eight industry categories construction miscellaneous nonmetallic mineral and stone products electrical machinery equipment and supplies aircraft and parts ship and boat building yarn thread and fabric mills rubber product and automobile repair and related service The Haenszel odds ratio was used to estimate relative risk RR To increase statistical power and provide a more direct measure of causation efforts were made to classify study asbes- stubjects in terms of the probability of occupational tos exposure A subset of jobs and another subset of in- dustries were selected for which exposure to asbestos was considered either possible or likely Tables 2 and 3 These subsets were developed by one of us H.C.L. with- out reference to information about disease status Compari- sons of control proportions with occupational asbestos Mesothelioma in Connecticut et al org d , , 2 F nn ee e ae we eee i i Sc Table 2 - Esumates of the Probability of Asbeads Exposares in Two Categories by U.S. Census Code and Job Tile U.S. Cenzus ---- ----- Likely Job Title Caligury U.S. Census Coda Possibla Job Titl -012 Electrical and electronic engineer 013 Industrial angincor 013 0 Mechanical engineer 4 Boilermaker +386 -522 -525 534 +601 0 Railroad and cor shop 0 Plumbers and pigslitters Power 1131 on operator =Replers and caters Asbestaansd insulation workers 615 622 = Ory wall installers installers and Lather Furnacemen smelter- 751 men and pourr Construction laborans excluding carpenters helper 006 011 = Arransutical and estronautical Engineer Civil Anginair 022 Sales engineer 023 Engineer ... 058 140 = Personnel and labor relations workers Teachers callige and university 142 Elementary school teachers -151 Chemical techniciane | 15Z Gratumen ' 173 Technicians n.e.c. ; 190 Painters and sculptor | 216 Managers and superintendents building ' 221 Officers pilats and pursers ship H adjusters 326 and t 403 Blacksmiths Blacksmiths | 410 Brickmasons and stanemasons 413 Cabinetmakers 415 Cerpenters 17 -130 Cranemen derrickmen hokimen Electricians 0433 136 Electric power lineman and cablemen 0 Excavating grading and read machine operators *** bulldozer 441 442 146 Foramen noc Forgemen and rammermen Heat treaters annealers and temperers 454 355 461 471 Jub and die waters mets Locomotive anginaer 0 Machirusts Machanics and repairmen aircraft 1473 Automobile mechanis 481 Heavy equipment mechanics including diezzi 182 Household appliance and accessory installers and machanic 133 492 Loom fixers Miscellaneous mechanics and repairmen 495 specified mechanics and reagirmen 502 503 Millwrights Molders metal +510 514 533 535 =Painters construction and maintenance Pattern and model makars excluding paser Rollers and finishers metal Sheetmetal workers and tinsmiths 545 Stationary engineers 550 0 Structural moral craftsman 552 Telephons installers and repairman 61 Toal dia makers 610 = Chachar miners and inspector manufacturing 11 Clothing araners and pressen 621 +623 641 Filers polishers sanders buffers Garage workers and pry station atiendan Mixing operatives 650 651 661 Drill prom operatives Grinding machine operatives Sailors and decanands 662 1670 1672 7673 7674 1680 1681 690 0631 Sawyer Cerding lacking and combing operates Spinners twistars and winders Weevan Textile operatives n'a Wolders and cutter Winding mparative nac = Machine operatives macallaneous specified Miscellaneous operatives 695 10 752 -760 = Not specified o2eretroer Motorman mine factory logging camp etc. Freight and material handlers Langhoramen and stevedores Hardressers and cosmetologists cosmetologists An accupation identified in referenca sources as having potential for asbestos exposure of stivally described in conjunction with a casa in the literatura T Occupations in lax ile lectering that need further investigation to determine whethaf labest textiles were involved in distinct from coman wool or manmade liber ... 'not othenens a exposure possible and likely were analyzed separately for each of three sources of information - job title industry title and job title and industry title For each of these comparisons adjustment was made nonsimultaneously nonsimultaneously for age 30 to 49 years 50 to 69 years 70 to 89 years year of Table 3- 3- Estimate of the Probability of Asbestos Exposures in Two Categoria by U.S. Census Coda and Industry Tide . U.S. Census Ced > _ Libily Industry Title Category | U.S. Consus Code Possible Industry Tile TT _ 057 087 068 053 138 = Nonmetallic mining and quarrying cept full General building contractors = General contractors except building = Special trade contractors Miscelleneous nonmetallic minera Ad stone products 139 14 | 18 Tegy Jurnancer el work falling are tinghing mills Other primary iron and steel industnes Primary sluminum industries 149 Other ammary nonferrous industna 168 = Miscellaneous fabricated metal products 177 Engines and turbines 199 Household appliances 207 Radio TV and communication Quigment Quigment 208 = Electrical machinery equipment and supplies 4.c 209 Not specified electrical machinery Ccaia ment and cuaalics 227 Aircraft parts 228 Shipbuilding and bost building and ragarring 229 Railroad locomotives and ement 233 Scientific and controlling instruments 258 6 77 529 539 Drone Electric light and power Water Epply Electrical goods - wholesale 0 Machinery equipment and supplies - orel 558 568 553 = Petroleum product = whole 0 Paper and it products - wholesale Lumber and construction mat- mat- Whelagala 607 639 Lumber and building material retailing Moter vehicle dealers 647 868 Tire carry and accemary dealers =Houshold appliances TV and radio ARE 757 Automobile repair and related sirvice 779 917 Launcaring Launcaring cleaning and other garment service Federal public administration administration 927 327 State public administration Locat public administration 127 Cement concrete aypsum and plaster 178 158 289 products = Structural clay productt Fabricated structural matal pronuc Beverage industries , , M,iscellaneous textile mill pradurs JZ8 Pulp paper end paperboard mills 337 Paperboard conterners and ba 348 Plastics synthetes and raging excluding fibers 379 Aubber products 407 417 019 Retroeds and railway express RVICE Trucking service Water transparation 427 56 609 Air transportation Alcoholic beverages whoisjala Department and mail order establishments 627 Miscellaneous general marchandise stores 548 Gunline service stations 649 =Miscellanous vehicle dealers 758 Electrical repair shops 759 Miscellaneous repair services 05 Elementary and secondary schools 858 867 = Colleges and unIVERSITIES Educational seRVICES P.B.C. 868 Engineering and architectural services n t > not oerwise classified birth 1870-1889 1890-1909 1910-1929 1930-1949 and geographic location The 1966 labor market area LMA divisions of Connecticut were utilized for the geographic risk analysis Particular attention was given to the LMAS surrounding Connecticut's five largest urban areas and two rapidly expanding previously rural regions A scoring procedure was developed to provide an indicator of the duration and severity of occupational asbestosexposure for both cases and controls For each job title in the likely category that could be documented from DCs CDs or both for an individual a score of 2 was as- signed A job title from the possible group was given a score of 1 and from the unlikely subset a score of 0 These values were summed across all available time periods for which employment information was available Individuals lacking any employment history which included those never employed and those for whom data were missing were excluded Each of the remaining study subjects was assigned a final single job index of exposure This Journal of Occupational Medicine 25 No. October 1983 751 07/17/01 14:15 FAX 313 577 0706 SHIFFMAN LIBRARY 009/022 crude measure provided an ordered exposure variable which was categorized into five levels Level O included a job index of 0. level 1 included a job index of 1level 2 a job index of 2 level 3 job indexes of 3 and 4 and level 4 job indexes greater than 4. Each study subject with a job index of exposure was assigned to one of the five groups Although the medical records of some cases noted past occupational asbestos exposure this information could not be incorporated into the analysis since such data were lack- ing for controls and has not been systematically collected for cases over time Haenszel standardized odds ratios were com- puted comparing cases and controls across each of the four levels of exposure to no exposure Finally the Coch Haenszel Test of Partial Association was applied to test the exposure relationship for trend while controlling for the potential confounding of age which was stratified into year intervals 30 to 49 years 50 to 69 years 70 to 89 years The 90+ stratum with t00 few numbers to be informative two cases seven controls was excluded from the response analysis These results are reported for an estimated exposure index based on job only The coding of industries into the broad categories of the U.S. Census does not discriminate satisfactorily among jobs with different exposures Controls tended to be older at death with a mean age of 68 years as opposed to 64 for cases Table 4 They predominated in the earlier birth cohorts with 81 born prior to 1910. Since age and year of birth are likely to be related to occupational asbestos exposure as well as to disease status they were considered potential confounders and controlled for in the analysis whenever sample size per- mitted The confounding effect of these variables however was not substantial The standardized odds ratios differed minimally from the crude and simultaneous adjustment was not deemed necessary The proportions of individuals with at least one job title from DCs CDs or both were comparable for cases and controls and virtually complete using all sources - 98 for cases 99 for controls Table 5 The percentages with 1-4 and 5-8 job titles were nearly identical CDs provided fewer job and industry titles than DCs but more names of specific employers One year prior to death or diagnosis less information was obtained for controls from CDs most likely Table 4 - Demographic Characteristics of Cases and Controls Mean year of death or diagnosis Mean age at death or diagnosis Birth Cohort Distribution % 1870-1889 1870-1889 1870-1889 1890 - 1909 1910-1929 1910-1929 1910-1929 1930 - 1949 Cases 1969 64 8 56 33 3 100 Controls 1966 68 200020002000- 20 0100 Males older than 30 years at death or diagnosis born after 1874 752 attributable to the larger proportion of retirees in the latter group For all other time periods the percentages of cases and controls with a job or industry title were similar Using both CDs and DCs at least one industry title was available for 89 of cases and 90 of controls Results We have described secular and time trends for mesothel ioma in Connecticut from 1935 through 1977 in an earlier report In the present control occupational risk analysis for the years 1955 through 1977 based on job title alone the more than twofold risk for cabinetmakers and carpenters and the nearly fourfold risk for plumbers and pipefitters were significant p < .05 Table 6 Excess risk was observed for engineers masons electricians foremen and painters but in none of these categories did it reach statistical significance at the .05 level It should be noted that for the job- and industry analyses the study provided adequate power to detect only large associations for the less common categories of employment Fourteen of the 15 cases among the carpenters were diagnosed as pleural mesothelioma and the single case of periotoncal mesothelioma occurred in the only individual who had worked in a boat yard All seven plumbers and pipefitters pipefitters were registered at the CTR with pleural mesothelioma and all death certificates reported them to be in this iob category Although CD data were available for only four of these cases it was in perfect agreement with DC data and revealed first cmployment in this category to be at least 30 years before diagnosis for each A parallel comparison of cases and controls using industry title alone revealed a significant association with the rubber industry relative risk RR = 5.08 < .01 Table 7 which was particularly striking when limited to subjects 70 to 59 years of age at death or diagnosis RR = 16.97 P < .005 Three different employers were represented among the five individuals with pleural and one with peri- toneal mcsothelioma who had worked at one time in the rubber industry : The proportion of cases with possible or likely exposure to asbestos on the basis of job title was 67 for the entire state yielding an adjusted RR of 1.63 (op < .01 The attributable risk AR in the exposed group was 39 There was little variation in risk across these geographic regions The study provided more than 90 power to detect relative risks of 2 or more at the .05 level for this comparison On the basis of industry title the overall proportion considered to have been exposed was 66 with an RR of 1.36 p < .10 and an AR of 26 Power calculations for this portion of the analysis yielded results similar to those described above Substantial interregional variation was observed in the percent exposed and in the risk for disease One large industrialized region LMA1 exhibited nearly a four risk p = .02 One employer in LMAI accounted for three times as many cases six as controls two with an unadjusted RR of 9.83 All the cases from LMAS with the exception of one with industry un- known had worked at one time in an industry judged to be associated with probable or possible exposure Histologic review of all malc cases from LMA1 an area in which an asbestos plant is located and LMAS an area in Mesothelioma in Connecticut et al wh tw ser the ava crit tor adj vidi mo En Br Ca Ele Fo Pai Plu 14 latter cases Using ilable thel arlier nalytitle and and risk men each oted tudy tions teen d as oneal had Iters ma : job of and 30 __ Table 5 - Completeness of Occupational Data for Cases and Controls From Death Certificates and City Directories Source % with Job Title Cases Controls % With Industry Title Cases Controls % With Employer Name Cases Controls DC 927 96 CD 76 69 prior to Ox 46 26 10 yr prior to Ox- 53 42 20 yr prior to Ox 46 45 25 yr prior to Ox 41 39 30 yr prior to Dxt 30 35 40 yr prior to Dx 26 24 50 yr prior to Dx 10 18 DC and CD 98 99 1-4 job titles 5-8 job titles 71 72 27 27 73 69 45 43 39 36 30 19 89 . 85 59 41 67 71 53 23 47 17 40 45 28 45 40 29 39 34 27 36 31 25 23 19 15 14 3 8 94 NC NC bee Lee * Uninformative titles such as retired student excluded When seven cases in living persons excluded from the denominator percentages become 96 76 62 I Cases less than 20 years of age at search year excluded from denominator $ NC indicates not calculated Total number ofjobs for cases = 475 3.23 for controls = 1 412 control which shipyards are located resulted in reclassification of two % and one 17 respectively as not mesothelioma or probably not mesothelioma There was no observable indication of diagnostic bias positives in these regions where knowledge of an exposure hazard was available in the medical community Using exposure either through job or industry as a criterion the statewide proportion of cases with an indicator of occupational exposure was 85 yielding an ageadjusted RR of 1.57 p < .05 and an AR of 36 In an examination of a birth cohort effect all individuals except those born between 1930 and 1949 were more likely than controls to have been exposed to asbestos on the basis of their job title The differences were statis tically significant RR = 2.16 p < .02 for the 1910-1929 cohort only The overall adjusted 1870-1889 18901909 1910-1929 1930-1949 RR was 1.69 p < .01 Utilizing the job exposure score as previously defined a monotonic increase in risk associated with higher levels of estimated asbestos exposure was suggested particularly for the oldest age group Table 8 There was a slight increase Table 7 - RR of Mesothelioma Associated With Selected Industry Categories 95 Confidence Table 6 - RR of Mesothelioma Associated With Selected Job Categories wo. 95 Industry Title Construction Miscellaneous nonmetallic RA 1.21 Interval N .60 2.45 45 a Job Title Confidence AR Interval N mineral and stone products 1.64 .15 18.06 3 Electrical machinery Engineers 2.72 .85 8.68 11 Brickmasons and stonemasons 2.152.15 .37 12.50 5 Cabinetmakers and carpenters 2.25T = 1.13 4.48 35 Fe Electricians Foremen 1.29 1.57 .39 4.24 14 .84 2.94 50 Painters constructiaonnd 1.39 .52 3.71 20 maintenance e Plumbers and pipefitters 3.87 1.38 10.82 13 N indicates the number of male cases and controis older than equipment and supplies Aircraft and parts Shipbuilding and boat building Yarn thread and fabric mills Rubber product Automobile repair and related service 2.79 1.03 .86 6.67 20 .43 2.49 25 . 1.09 .35 3.42 16 .57 .17 1.92 20 5.08 16.11 10 .65 .08 5.53 6 * N indicates number of male cases and controls older than 30 mie 30 years at death or diagnosis born after 1874 who evar neuen" worked in the category total N for each independently + calculated RR was 611 147 cases 464 controls eee ,".05 years at death or diagnosis born after 1874 who ever worked in the category total N for each independently calculated RA was 611 147 cases 464 controls t .01 me cmE Journal of Occupational Medicine 25 No. October 1983 753 Table 8 - RR of Mesothelioma Associated With Level of Occupational Asbestos Exposure by Aga Age Group Level of Occupational Asbestos Exposure xfor 0 1 2 * at N Trend 30-49 50-69 70-89 ages 1.00 1.00 1.00 1.00 .39 1.11 2.19 1.19 1.17 1.59 1.60 1.78 4.59 1.34 2.20" I 1.67 5.35 2.73 66 257 272 61 NS NS .0001 .0005 ~ Level 3 is exposure scores 3 or 4 Lavel 4 is exposure scores 5 to 16 * AR could not be calculated due to 0 denominator one case 0 controls with exposure .001 adjusted relative risks " P .005 for the 30 to year group but numbers were small and the variances of the RR estimates were large There was a sizeable number of cases 80 and controls 177 in the 50- to year group and a fairly constant risk asso- ciated with increasing estimated exposure was indicated Those males 70 years or older n = 272 with job exposure scores in levels 3 and 4 exhibited highly significant relauve risks for this disease The ARs for those exposed in these two levels were 78 and 81 respectively The test for trend that compared the relative proportions of cases and controls across increasing levels of estimated asbestos exposure while controlling for age was highly significant overall p < .0005 and for the 70 to year age group p < .0001 Discussion The major difficulties encountered in a noninterview retrospective study of an mesothelioma association relate to the inadequacy of occupational histories the potential for misclassification of exposure status and errors in diagnosis Although partial employment data were obtained for nearly all study subjects complete work histories were available for very few and information regarding part- time work or hobbies was completely absent The level of completeness varied geographically with the less mobile industrialized regions having more complete CD coverage than the more rural less populated areas Completeness by geographic region did not differ however between cases occupa- and controls For the seven cases in living persons tional information could be obtained from CDs only When the analyses were repeated excluding these individuals however the findings were unchanged These occupational history limitations were balanced in part by the advantage that respondent memory bras and faulty interviewing tech- niques associated with widely publicized carcinogenic hazards such as asbestos were avoided in this noninterview approach Although the inability to reconstruct dust measurements prevented direct examination of a response relation ship the job exposure index a correlate of asbestos exposure demonstrated increasing disease risk with higher 754 if An scores particularly for the 70 to year age group attempt was made to test the possibility of a systematic inflation of case scores due to more complete occupational information for the diseased population Job title availa bility for the maximum of eight time periods searched was comparable for both groups Table 5 with 71 of and 72 of controls having 1-4 job titles and 27 of each having 5-8 job titles In addition the stratified relative risk calculations made adjustment for the large proportion of retirees in the control group with fewer job titles one year prior to death The elevated risks associated with the older age group and with the 1910-1929 birth cohort are consistent with the poor dust control measures in most workplaces prevalent in earlier years Peto showed et al a wide in their review of a number of studies variation in the peritoncal ratio among asbestos persons We have determined this ratio in our cases and attempted to relate it to some parameters that scom to influence its distribution An analysis of proportions of cases of mesothelioma by site within each of three age groups 30 to 49 years 50 to 69 years and 70 to 89 years for each sex separately showed that among men the proportions of pleural disease increased as age in- creased while the proportions of peritoneal disease decreased Pleural mesothelioma accounted for 79 of cases aged 50 to 69 years and 93 of cases aged 70 to 89 years at diagnosis Job AR in the exposed was about 80 for these older men Results Table 6 for carpenters and cabinetmakers 14 of 15 pleural and plumbers and pipefitters seven of seven pleural are consistent with the above proportions and with Table 8 in suggesting that pleural mesothelioma in men over 50 in Connecticut is highly likely to have been associated with and probably caused by exposure to asbestos at work These data also indicate that occupational exposure to asbestos probably explains most of the disease in these older men and that it began in the 1930s Peto et al17 showed that mesothelioma death rates were independent of age at first exposure and it may therefore be assumed that age in itself has no direct influence These authors did show a strong correlation between disease and length of time since first exposure The fact that the inci- dence of mesothelioma of the pleura increases sharply in the males in the older age groups with the higher exposure scores in our cases is consistent with the long latency known to be associated with this disease This is also in conformity with Poto et al's findings The potential for random misclassification of exposure status based on subjective blind review of limited work histories restricts our ability to draw firm conclusions because such errors produce attenuation toward an RR of This is particularly relevant with regard to the true proportion occupationally exposed and the true magni- tude of the RR which is likely to be higher than our find ings indicate Blind subjective review has also been used by other investigators in estimating exposure but most often in conjunction with interview 18,19 It is widely held that relatively low exposure levels 20 to SO years prior to diagnosis may lead to the development of mesothelioma The cases described with no known ex- posure may fall into this category may have been exposed from the general environment or may be related to some Mesothelioma in Connecticut et