Document 2jXrdmnzkGVyVQQQ6Yg5np466

Mesothelioma in Connecticut, 1955-1977 Applied Health Sciences Oca Wcoc* Sc.D. (41J)J47-7IFt Occupational and Geographic Associf Mary Jane Teta, M.P.H.; HHton C. Lewinsohn, M.B., B.Ch.; J. Wlster Meigs, M.D.; Romeo A. Vidone, M.O.; Linda Z. Mowad, R.N,; and John T. Flannery, B.A. . - AH'eastt of malignant mesothelioma (201J and other primary malignant pleural turnon (19) reported to the Connecticut Tumor Registry from 1955 through 1977 were studied In an attempt to Identify high-risk Jobs, Industries and geographic locations end to estimate the risk attributa ble to asbestos exposure In the workplace. Data were ob tained 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 pipe fitters, 3.87 (p < .05); and for persons "ever employed" In the rubber Industry, 5.08 (p < .01). Occupational exposure was Indicated In 8576 of the eases; attributable risk (AR) was 36%. Risk Increased with greater exposure and older age. AR was 81% In men aged 70 to 89 yean at diagnosis. Reduction of unnecessary occupational asbestos exposure remains the highest public health priority. In 1980, Lewinsohn et ill described mesothelioma In Connecticut from 1935 through 1977. Problems of diagno sis and ascertainment made results for the yean prior to From she Val* School of Epidemiolo(y and PsihUc Health, New Haven, Conn. (Ms. Ten, Associate In Research, Connecticut Cancer Epldemloloir Unis, Or. Melp, Qintcal Professor of Epidemiology and Public Health and Ms. Mowed. Associate In Reaeanh); the Union Carbide Carooration, Danbury; Conn. (Dr. Uwfntohn, Assistant Corporate Medical Director); the Vale University School of Mcdidne (Dr. Vidone, Associate Clinical Professor of Pathology); end the Connecticut Tumor Registry, Connecticut Sun Depart ment of Health Services, Hertford (Mr. Flannery, Director). Mi. Ten It now affiliated with Union Carbide Corporation, Danbury, Conn. Address correspondence to Union Carbide Corporation, Health, Safety and Environmental Affaire, Dept. P2, 1 Ridgebury Re., Danbury, CT 05817 (Mi. Tea). Thlt Invest!ptlaa was supported by frente NOI-CP-JJ335 and NO1-CP-SI003 awarded by the National Oncer Irudtuu, US Department of Health and Human Servlcea, and by the Institute of Occupttlont! Medicine end Hygiene, Ytlt University School of Medicine. 1955 of uncertain value. From 1955 through 1977 the age-adjusted rates among males rose from about 0.19 to 0.60/100,000 and among females from 0.13 to 0.19/ 100,000. Bruckman et al3' claimed In 1977 that increases in the disease 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 male-female ratio is more consistent with occupational exposures of men at work. Bruckman el al were unable to provide complete occupa tional histories for the 133 diagnosed cases of mesotheli oma (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 ng/m*, measured over a 30-day Interval.3 This proposal was based on estimated asbestos concentrations at several selected sites in Connecticut. ' Mesothelioma is a rare disease with approximately 23 cases per million population expected annually.4 The proportion of eases not associated with some form of asbestos exposure has been reported to be near 15N.*-7 This disease may serve as a marker for unsuspected past asbestos exposure. The present study was designed pri marily 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, In dustries, specific employers, and Connecticut geographic locations that are associated with an excess risk for meso thelioma and that may alto 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 eases that may be due to occupational asbestos exposure, other as yet undetermined risk factors, or possi ble asbestos exposure from the general environment. There remain numerous unanswered questions concern ing the existence of a threshold and the nature of the as- Journal ol Occupational Medicina/Vol. 25, No. 10/0ctober 1983 7 SC-ELEC-08370 PA-00374.80 bestos-mesothelioma dose-retponse relationship.*-* The data available allowed us to approach these problems indirectly. In lieu of dust measurements, job and industry titles, ascertained for study subjects for periods up to SO years, were used as indicators of exposure. Methodology Since mesothelioma has often been confused with other malignant turnon, an anatomic pathology review of ail cases reported to the CTR between 1955 and 1977 was undertaken. Histologic material, along with gross autopsy and clinical reports, was submitted to one of us (R.A.V.) for review. No personal identifiers or occupational data were included. Although the final results of this review will be published separately, specific findings will be discussed in the context of the present report. The CTR registered 196 cases of primary malignant mesothelioma during the years 1955 to 1977 inclusive. With the exception of the Veterans Administration (VA) Hospitals in Connecticut, it is mandatory for hospitals to report diagnosed malignant neoplasms to the central registry. A review' of all autopsy records from the larger of the two VA hospitals in the state from 1955 through 1977 yielded five additional cases of mesothelioma, bringing the total number to 201. This included 137 cases with site pleura, 29 with site peritoneum, and 35 of other or un-' known sites. Concerns about diagnostic sensitivity prompt ed the inclusion of 19 cases reported as pleural tumors other than mesothelioma during the same 23-year period. These concerns were justified by the slide review that identified several cases of mesothelioma In this group. The total case study population size was 220 (Table 1). Medical, demographic, and occupational data have been collected for these 220 cases. Similar information was gathered by Roush et al10 for a computer-generated ran dom sample of 604 decedents (1955-1975) aged 20 to 98 Table 1 - Sex, Age and Diagnostic Clasrfficetioa of 201 Cuts of Malignant Mesothdlomt end 18 Other newel Tumors Oiognoad in Connecticut. 19SS-1B77 Olignasb* Milas Females Total Mom Ago* Pleural ' moothtliome Pleural tumor (other then meiotheiiomai Peritonei! mete(hellome Mesothelioma et other situ end it unknown sites 100 11 18 21 37 137 8 11 29 14 35 63 63 59 54 Tote) ISO 70 220 61 World Heelth Organiietien (1976). * orig'mrily reeortfid by CTR 1 At diagnosis yean 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)l Death certificates (DCs) provided demographic data and usual occupation for study subjects at time of death. Oty directories (CDs) were searched for residential and employ ment histories 1,10, 20, 25,30, 40, and 50 yean prior to date of diagnosis or death, provided that the subject was at least 20 yean old at the time.11 The Price and Lee Oty Directories, which are available for about two thirds of .Connecticut towns from 1890 to 1980, have a target population 'of 92% of the adult mates 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-digit 1970 U.S. Census Industrial and occupa tional codes12 were assigned to the employment informa tion ascertained. Industrial coding was determined oh 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.12 The study population for occupational analysis was re stricted to males over 30 years of age at death or diagnosis. A large proportion of females (46% cases, 3156 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 bom after 1874, controls bom prior to 1875 were ex cluded. There remained 611 male subjects for the occupa tional analysis: 136 mesothelioma cases; 11 cases of pleural tumors, other than mesothelioma; and 464 controls. The case-control ratio was approximately 1:3. 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 or indus 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 cate gories (construction; miscellaneous, nonmetallic mineral and stone products; electrical machinery equipment and supplies; aircraft and parti; ship and boat building; yam, - thread and fabric mills; rubber product; and automobile repair and related service). The Mantel-Haenszel odds ratio was used to ettimate relative risk (RR).14 To increase statistical power and provide a more direct measure of causation, efforts were made to classify study stubjects in termi of the probability of occupational asbei- 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 tutus. Compari sons of else-controt proportions with occupational asbestos 750 Mesothelioma in Connect:cut/Teta et el liny im w--< emMK\ 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) for age (30 to 49 yean, 50 to 69 yean, 70 to 89 yean), year of 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.1* 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 indica tor of the duration and severity of occupational asbestos exposure 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. Indi viduals lacking any employment history, which included those never employed and those for whom data were mis sing, were excluded. Each of the remaining study subjects was assigned a final single job index of exposure. This Journal ol Occupational Medicina/Vol. 25, No. 10/0ctober 1983 751 crude mcuure provided an ordered exposure variable, which was categorized into five levels. Level 0 included a job index of 0, level 1 included a job index of 1, level 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 wilh a job index of exposure was assigned to one of die 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.) . ' Mantel-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- ran-Mantel-Haentzel Test of Partial Association16 was applied to test- the disease-exposure relationship for trend while controlling for the potential confounding of age, which was stratified Into 2&year intervals: 30 to 49 yean; 50 to 69 yean; 70 to 89 yean. The 90+ stratum with.too few numbers to be Informative (two cases, seven controls) was excluded from the dose-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 yean as opposed to 64 for cases (Table 4). They pre dominated in the earlier birth cohorts with 8196 bom 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 confounden 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, COs or both were comparable for cases and con trols and virtually complete using all sources -- 9836 for cases, 9936 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 in-' formation was obtained for controls from CDs, most likely Table 4 - Omogrephlc Chartctirfatla of Cam anil Ceatrob* Cm Centrals Mean year of death er diagnose Mean age at death or dhgnosii Birth Cohort Dbtribution, K 1870 -1883 . 1890- 1909 1910 - 1929 1930 -1949 1999 94 8 56 33 3 100 1966 . 66 32 49 . 18 1 too * Milas older than 30 yean at death er diagnosis, born after 1874 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 CtH and DCs, at least one industry title was available for 8936 of cases and 9036 of controls. Results - We have described secular and time trends for mesothel ioma In Connecticut from 1935 through 1977 in an earlier report.1 In the present case-control occupational risk analy sis for the yean 1955 through 1977, based on job title alone, the more than twofold risk for cabinetmakers and carpenten anti the nearly fourfold risk for phimben and plpefitten were significant (p < .05) (Table 6). Excess risk was observed for engineen, masons, electricians, foremen, and painten, but in none of these categories did it reach statistical significance at the .05 level. It should be noted that for the iob- and industry-specific analyses the study provided adequate power to detect only large associations for the less common categories of employment. Fourteen of the 16' cases among the carpenten were diagnosed as pleural mesothelioma and the single case of periotoneaJ mesothelioma occurred in the only individual who had worked in a boat yard. All seven plumben and pipefitten were registered at the CTR with pleural mesothelioma, and all death certificates reported them to be in this job category. Although CD data were.available for only, four of these cases, it was in perfect agreement with DC data and ' revealed fint employment in this category to be at least 30 yean before diagnosis for each. ;. A parallel comparison of cases and controll using indus try title alone revealed a significant association' with the rubber Industry (relative risk |RR| 5.08;p < .01) (Tabic 7), which was particularly striking when limited to subjects 70 to 89 yean 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 mesothelioma who had worked at one time in Che rubber industry. The proportion of cases with "possible" or "likely ex- - posure" to asbestos on the basis of job title was 6736 for the entire state, yielding an LMA-adjysted .RR of 1,63 (p < .01). The attributable risk (AR) in the exposed group was 3936. There was little variation in risk across these geo graphic regions. The study provided more than 9036 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 6636 with an RR of 1.36 (p < .10) and an AR of 2636. 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-fold risk (p = .02). One employer in LMA1 accounted for three times as many cases (six) as controls ' (two) with an unadjusted RR of .9.83. All the cases from LMA5 (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 male cates from LMA1 (an area in which an asbestos plant is located) and LMA5 (an area in 752 Mesothelioma in Conneeticut/Teta et al Tibia 5 - Completeness of Ocaipotmnd Oite for Cam end Controb From Death CertHkatn and Ctty Directories . - Source 96 with Job Tkfe* . Cam Controb 96 With Industry Title Cam Controb X With Employer Name Celts Controb - DC 92* 96 73* 85 CO 76 69 69 67 lyrpriortoOx 46 26 45 23 10 yrprior tb 0x7 53 42 43 40 20 yr prior to 0x3 46 45 39 45 25 yr prior to 0x3 41 39 36 39 30 yr prior to Da* 30 39 30 ` 36 40 yr prior to 0x3 26 24 19 23 . S0yrpriorto0x3 10 18 9 14 DC tnd CD 14 job titled 5-8 job title*1 98 99 89 . . .71 72 4 ...27 27 94 .4 ** Uninformative tltfosiuches retired, student excluded * When mn urn in living persons esdeded from tht denominator, percentages become 98,76,62 t Cm tea then 20 yeers of apt it inrch yew txduded from denominitor 6 NC indicates not calculated ' ' D Total number of fobs for cam > 476 (3J3/cuel;for controb 1,412 (3.04/control) 59* 71 47 45 40 34 31 19 3 NC 444 41 ` 53 17 28 29 27 25 15 8 NC* ...4.4 which shipyards are located) resulted in reclassification of two (896) and one (1796), respectively, as "nos mesothelio ma" or "probably not mesothelioma." There was no ob servable Indication of diagnostic bias (false-positives) in these reports where knowledge of an exposure hazard was available in the medical community. Using "exposure" cither through job or industry as a criterion, the statewide proportion of cases with an indica tor of occupational exposure was 8596, yielding an ageadjusted RR of 1.57 (p < .05) and an AR of 3696. In an examination of a birth cohort effect, all indi viduals, except those bom between 1930 and 1949, were more likely than controls to have been exposed to asbestos Table 6 - RR al MesothtHoml Associated With Selected Job Categories Job Tide 95X Confidence RR lateral X* Engineers ' Brickmturn end ttensmasoni Cebinaimikin end carpenters Electricians Foramen Pilnttrs, construction, end maintenance Plumbers and pipefitters 2.72 2.15 . 2JS* 1.29 1.57 1J9 3J7* (.85, 8.68) (.37.12.50) (U3. 4.48) (JO, 4J4I (.84, 2J4) (.52, 3.71) (1J8.10.62) 11 5 35 14 50 20 13 N Indicates the number el ipele casts and cenireb elder thtn 30 years it death or diagnosis, born after 1874, who "ever worked" in lha category; total N for each independently calculated RR was611 (147 casts,464controls) T p <.05 on the basis of their job title. The differences were statis tically significant (RR 2.16, p < .02) for the 1910-19K cohort only. The overall cohort-adjusted (1870-1889; 1890 1909; 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 Tebb 7 - RR ol MteothiKomi Associated With Selected Industry Categories Industry Title . 9SX Confideata RR laterval H* Construction Mbcalbnteua nanmenlltc mineral end (ton* products Electrical machinery equipment, end supplies Aircraft end parts ' Shipbuilding and ban building Yam, thread end fabric mills Rubber product Automahilt repair end rotated service 1J1. (JO. 2.45) 45 1.64 (.15, 18.06) 3 2.78 (.86. 6.671 20 1.03 (.43, 2.49) 25 1.09 .57 5.08' .6$ (J5. 3.42) (.17. 1J2) (1.60,16.111 (.06, 6.531 16 20 10 6 . N Indicates number of malt cam and controls older then 30 yeera et death or diagnosis, bom liter 1874, who "ever worked" In the citegory; total N lor each Independently calculated RR war 611 (147 cam, 464 controls! * A <.01 Journal of Occupational Madicine/Vol. 25, No. I0/0ctober 1983 753 Tabial - RR ef Mesothelioma Atsetiatad With Level al Oecapetfenal Atbtites Expatsre by Agi As* Croup 3049 5069 7089 All apt*1 Law) of Occupational Asbestos Exposure x*fer 0 1 2 3* 4 N Trend 1.00 M .47 1.17 ... 66 NS 1.00 1.11 1.59 1.60 1.67 257 NS 1.00 2.19 1.78 4.59* SJ5* 272 .0001 1.00 1.19 1.34 2^0* 2.73* 611 .0005 * levil 3 b expoaire Kara 3 or 4 * Levrl 4 b exposure stores S to 18 t RR could not bo caiculatsd duo to 0 denominator; ona cast, 0 ' control* with "exposure" I p<.001 . * Aga-cdjuited relative risks 1 p<.005 . for the 30 to 49-year-old group, but number* were small and the variance* of the RR eitlmate* were large- There was a sizeable number of cases (80) and controls (177) in the SO- to 69-year-old group, and a fairly constant risk asso ciated with Increasing estimated exposure was Indicated. Those males 70 years or older (n 372) with job exposure scores in levels 3 and 4 exhibited'highly significant relative 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, white controlling for age, was highly, significant overall (p < .0005) and for the 70 to 89-year-old age group (p < .0001). Discussion The major - difficulties encountered in a noninterview retrospective study of an asbestos-mesothelioma association relate to the inadequacy of occupational histories, the potential for misdassificatlon of exposure status, and errors in diagnosis. Although partial employment data were ob tained 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 and controls. For the seven cases in living persons, occupa 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 pan by the advantage that respondent memory bias 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 dose-response relation ship, the job "exposure" index, a correlate of asbestos exposure, demonstrated increasing disease risk with higher scores, particularly for the 70 to 89-year-old age group. An 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 cases and 73% of controls having 1-4 job titles and 27% of each having 5-8 job titles. In addition the age-ttratified 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 g(Oup and with the 1910-1929 birth cohort are consistent with the poor dust control measures in most, workplaces prevalent in earlier years. Peto et al17 in their review of a number of studies showed a wide variation in the pleural-peritoneal ratio among asbestos-exposed persons. We have determined this ratio In bur cases and attempted to relate it to some param eters that seem 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 yean and 93% of cases aged 70 to 89 yean at diaptosis. Job AR in the exposed was about 80% for these older men. Results (Table 6) for carpenters and cabinetmakers (14 of IS pleural) and plumbers and pipe- fitten (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 "ex posure" scores in our cases, is consistent with the long latency known to be associated with this disease. This is also in conformity with Peto et al's findings. ' The potential for random misdassification of exposure status, based on subjective, "blind" review of limited work histories restricts our ability to draw firm conclusions, be cause such errors produce attenuation toward an RR of 1. 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 data.1*-1* It is widely held tharrelatively low exposure levels 20 to 50 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 754 Mesothelioma in Conneaieut/Tete et el other unknown etioiogic factor. Careful examination of the occupational data for these cases and the controls with no known exposure did not reveal any unusual differences. There were no geographical associations of peritoneal mesothelioma with asbestos cement pipe used in Connecti cut in a search made by one of us (J.W.M.) in a report to the Environmental Protection Agency. The possibility of misdiagnosis is Important. Dr. Ray mond Vesner, chairman of the World Health Organization Committee on Nomenclature of Lung Cancer, and one of us (J.W.M.) recently reviewed 964 randomly sampled autopsy cases reported to the CTR as primary lung cancer during the 45 years from 1935 through 1979. One of these was diagnosed as a mesothelioma. The five cases of meso thelioma in the present study identified from VA hospital autopsies Included two pre-1963 cases in which the initial diagnosis had been lung cancer. This suggests that in the past, as many as one or two per thousand cases diagnosed as lung cancers may have been mesotheliomas, but the propor tion is probably smaller at present because of Increased awareness by clinicians and pathologists. The association with the rubber industry requires addi tional exploration because of the lack of specific informa tion regarding the many aspects of manufacturing processes lumped into this broad category and the potential for chance association due to the examination of multiple comparisons. McDonald1* reported three cases and one control who were employed by a factory making rubber products in her North American survey of mesothelioma. These were selected from all male cases (150) and their matched controls who did not work In occupations asso ciated with likely asbestos exposure. Exposure to rubber among all 344 cue-control matched pairs in her survey did not reveal an elevated RR. The association was in fact in the opposite direction (RR = 0.6). . The manufacture of asbestos-containing friction materi als was associated with job histories in only three cases in the present study. First hire was in the 1920s and 1930s with time intervals of about 30 years before mesothelioma was diagnosed. Slide review confirmed a diagnosis of peri toneal mesothelioma In a female clerical worker (case 1) with approximately 30 years' employment. In this indi vidual asbestosis was also considered to be present Similar ly, in a male employee (case 2) with the same surname, a diagnosis of "possibly pleural mesothelioma" was made. These two individuals were discovered to be brother and sister-in-law. Their common relative (the husband of case 1 and brother of case 2) was employed by the same asbestos company for a period of at least 30 years and died at age 56 years of an acute coronary thrombosis. He resided consecu tively with his brother for at least 17 years and with his wife for over IS years prior to his death. The thlfd case from the same plant, that of a female clerical worker who had been employed there less than five years, was classified as "probably pleural mesothelioma." In a search of city directories by single years, no other employment was found for this woman. - Two of the three cases in employees at the asbestos plant were Included by McDonald and Fry30 in their recently reported cohort study, which was based on death certificate information and employee records. The diagnosis of mesothelioma, however, was not ascertained since no mention of this disease was made on either death certifi cate. The third person, a male who was employed during the period 1921 to 1932, was not included in McDonald and Fryt cohort which was defined as persons employed in the period 1937 to 1959 only. These three cases repre sented only small proportions (one of 30 males, two of 12 females) with mesothelioma in the LMA that included the plant making asbestos products. Most of the remaining male cases had occupational history indicators of asbestos expo sure at work. There was no support for the hypothesis of a significant residential risk to persons living in the vicinity of-this plant. The original case-control proportions among those residing in LMA1 at time of death or diagnosis were 20% and 12% for males and 17% and 18% for females, respec tively. After excluding all males with "possible" or "likely'' occupational asbestos "exposure," based on job title or industry title or both, there remained 9.5% of all male cases and 9.2% of all male controls In that LMA. No real residential difference .was observed for either males or fe males. This result may be related to the asbestos fiber type used at the plant, which McDonald and Fry reported to have been the less hazardous chrysolite and would, there fore, not be extrapolated to all asbestos products manu facturers. One of the female cases, an employee who worked at die asbestos friction materials plant, may have had domestic exposure from her husband who also worked there for many years. We explored this general- issue by reviewing cancer incidence among 193 spouses, the majority of whom were female. Twenty-seven case spouses have been reported to the CTR (1935-1978) with a confirmed malignancy. There are no reported tumors of the pleura, lung, peri toneum, or ovary in the spouse group. This provided no indication of domestic risk. However, since there were no control spouses, Inferences involving .domestic exposure were very limitecL ' Only two persons with "probable" cates and one with a "possible" case of mesothelioma were known to have worked In shipbuilding or repair. The LMA that included these industries showed no excess proportion of cases over controls. Sellkoff (oral communication, 1978) has suggested that heavy asbestos exposures occurred in the late 1940s and that cases might develop In the 1970s and later. The two "probable" cases with recorded shipbuilding employ ment in the present study were diagnosed in 1975 and 1976, which is consistent. The findings of Peso et al*1 how ever, (ndlcate that the consequences of wartime exposure may have been exaggerated. Future data from Connecticut should clarify this question. . Conclusion Difficulties in ascertaining.occupational asbestos expo sure histories in our study population indicate a need for better recordkeeping in industry, medical Institutions, and tumor registries. Our methodology, utilizing indirect means of ascertainment, has enabled us to estimate the extent to which occupation or industry may affect the incidence of - -mesothelioma among males in Connecticut, job-related or Industry-related factors appear to account for a large per centage of all mesothelioma cases in males diagnosed in the State between 1955 and.1977. Lack of detailed Informa- Journal of Occupational Medicine/Vol. 25, No. 10/October 1983 755 lion regarding the residual cases may obscure the true number occupationally exposed. The large proportion of cases of older men with some indication of occupational exposure, the increase over time in the male-female ratio, and the lack of difference between the proportion of cases and controls without evidence of occupational exposure residing in the LMA containing an asbestos plant do not provide support for the view that ambient air concentra tions were a major factor in influencing the observed incre ment in cases of mesothelioma during the course of the study period. The reduction of unnecessary exposure to asbestos in the workplace remains the highest public health .priority. Future studies of the mesothelioma cases recorded in the CTR should endeavor to clarify the clusters of cases in the rubber manufacturing industry and in the plant located in LMA1 where an RR of nearly 10 was observed. Collab oration of the industry or Industries concerned will be sought to explore the implications of these results. This will be attempted in conjunction with continuing surveillance of mesothelioma in Connecticut. ' Acknowledgments Lawrence Hally, Itagina Robinson, and Marianne Oelpo of the Connecticut Cancer Epidemiology Unit and Nora Naughton of the CTR provided technical assistance. References t. lewinsohn HC, Meigs |W. Tea M|, et el: The Influence of occupational and environmental asbestos exposure on the Incidence of malignant mesothelioma In Connecticut, in Wegner )C (Ed.): Biological Effects of Mineral Fibres. Lyon, F ranee: IARC Publica tions No. 30, vol 3.1980, PP 655-660. 2. Brockman L, Rubtno RA, Christine B: Asbestos and meso thelioma Incidence In Connecticut APCA / 27:131-126,1971. 3. Brockman L: A study of airborne asbestos fibers In Con necticut, In Cravatt CC. LaFleur PO, Helnrelch KF| (Eds.): Work* shop on Asbestos: Definitions and Measurement Methods. Washing ton, O.C: National Bureau of Standards Special Publication 506, 1978, pp 179-190. . ' 4. Cutler S|, Young |L, (Eds.): Third National Cancar Survey: Incidence Data. Washington, O.Cj US. Gov't Printing Office, No. 75-787.1975, vol 41, p 442. 5. Craighead IE, Motunan ST: The pathogenesis of asbestos associated diseases. N Engl I Mtd 306:1446-1455,1982. 6. Parkes WR: Silicates and lung disease, In Occupational Lung Disorders, ed 2. London: Buitcrworth A Co ltd, 1982, pp 333-333. 7. WhitwtR F, Scott I, Grlmshaw M: Relationship between occupations and asbestos-fibre content of the lungs In patients with pleural mesothelioma, lung cancer, and other diseases. Thom*'32: 377-386,1977. . 8. Becklake MR: Asbestos-related diseases of the lung and other organs: Their epidemiology and Implications for clinical pranks. Am Rev Htapir DU 114:187-327,1976. 9. Becklake MR: Asbestos-related diseases of the luap and pleura: Current clinical Issues. Am Rev kttplr DU 126:187-194, 1982. 10. Roush GC, Meigs |W, Kelly |. el si: Slnonatal cancer and occupations A case-control study. Am / Epldtmlol 111:183-193, 1980. 11. Price and Lee Cily Directory. New Haven, Conn.: Price and Lee Co., 1890-1977. 12. U5. Department or Commerce. Bureau of the Census: 1970 Census of the Population; Alphabetical Index of Industries and Occupations. Washington, O.C.: U.S. Gov't Printing Office, 1971. 13. Connecticut Labor Department: Connectlcut Menufacturing Directories, 1936-1973. Hanford: State of Connecticut. 14. Mantel N, Haeruxel W: Statistical aspects of the analysis of- data from' retrospective studies of disease. INCI 72:719-748,1959. 15. Connecticut Labor Department, Employment Security Division, Department of Research and Information: Commuting Patterns In Connecticut, |une 1966. Harford: Sate of ConnecU- cuL 16. Landis |R, Cooper MM, Kennedy T, ei al: A computer pro gram for testing average partial association In three-way contingency tables IPaacat). Compart Program! {Homed 9:223-246,1979. 17. Pew ), Scldman H, Scllkoff l|: Mesothelioma moruDty In asbestos workers: Implications for models of carcinogenesis snd risk assessment. Sr/Cancer 45:124-133,1932. 18. Milne |EH: Thirty-two cases of mesothelioma In Victoria. Australia: A retrospective survey related to occupational asbestos exposure. Sr/ /nd died 33:115-122,1976. . 19. McOenald AD: Malignant Mesothelioma In North America. Cancar 46:1630-1656,1980. 20. McDonald AD, Fry JS: Mesothelioma and fibre type In three American asbestos factories -- Preliminary report. Stand / Work Environ Htoltfi 8:53-58.1982. . 2). Ptto I, Henderson BE, Pike MC: Trends In mesothelioma incidence and the forecast epidemic due to.asbcstot exposure during World War II, In Pcto R. Schncldcrman M IEds.): Banbury Repost 9 Quantification of Occupational Cancer. Cold Springs Harbor: Cold Sprtnp Harbor Laboratory, 1981, pp 51-72. No Knowledge from Information In every sphere of modem life, the chronic condition is a surfeit of information, useless, poorly integrated, or lost somewhere in the system. Too many critics of the or ganizational and political sources of our troubles see diabolical plots where there is only drift, a taste for reckless adventure where there b only ignorance of risks, the machine ' tions of a power elite where there it, in William James's phrase, 'only a bloomin' buzzin' confusion'. --From Organizational InuiUgtna by Harold WUtnsky. Bask Books, New York. 1967. 756 Mesothelioma in Connecticut/Teta et si