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I I I I 1 I I I I I I I I I I I I A RETROSPECTIVE COHORT STUDY OF PROPORTIONAL CANCER MORTALITY AMONG CHINESE TAR FELT WORKERS Gong De-tian, Feng Ke-yu, Liu Chuen-hwa, and Cui Xiu juen Construction and Waterproof Materials Manufacturing Plant Workers' Hospital, Qiqihar, Heilongjiang,China In order to understand the malignant tumor mortality rate among Chinese tar felt workers and whether there are any etiological patterns associated with it, we conducted a 13-year (January 1, 1977- December 31, 1989) retrospective cohort study among the workers of 20 tar felt manufacturing plants in 15 Chinese cities. The cohorts were composed of exposed, mixed and petroleum groups. Workers from 19 plants of other industries (machinery, metal refining, textile) located in the same areas were selected as controls (Control 1); the specific death rates of residents of medium-sized Chinese cities were also used as controls (Control 2). -Additionally, workers in the petroleum industry were studied. We used life tables for person-year calculations, collected death records, calculated expected death rates and standardized mortality ratios (SMR), and examined the effects of smoking on lung cancer death rates. The results showed the SMR of all cancers for the male tar felt making cohorts in the exposed group was 1.23 (P < 0.05), in the mixed group was 1.34 (P < 0.01), and in the petroleum group was 1.04. (Table 1) The lung cancer excesses were especially evident when the cohorts were compared to both controls (Controls 1 and 2); the respective SMRs for the three cohort groups were 3.88 (P < 0.01), 2.83 (P < 0.01), 3.35 (P < 0.01), 2.67 (P < 0.01), 5.14 (P < 0.01), 3.13 (P < 0.01). (Table 2) The exposed group and its subgroups of high- and medium-exposure work areas showed significant lung cancer increases, but the low-exposure subgroup showed no significant increase. A dose-response relationship was demonstrated between the lung cancer in tar felt workers and their levels of tar exposure. Furthermore, exposure to tar and tobacco smoking was found to have some enhancing effects on lung cancer in males. We also calculated the standardized proportional mortality ratios (SPMR) and the proportional cancer mortality ratios (PCMR) but found them to be similar to the SMRs. In summary, this study found a significant increase in lung cancer deaths among tar felt workers and a dose-response relationship to their tar exposure. The strong correlation between lung cancer in felt workers and their occupation indicates a need for lung cancer preventive measures for these workers. I

Table 1. Standardized Mortality Ratios of Malignant Tumors Among Male Tar Felt Workers ., . , . .. T:kjroealGroup . Y.lxeducwp .... ... .. . Peaoteimi0roap.... ' . . . . . , $WW4rdI¢ed... . StwAarJbcd . . .. . . .S~.wd+tdvd Srand vdizcd Md'mm-eizod . Stmlud'cc d . Ficdiwn-.izcd. . .. Sbknda. d"2cd M<di.-arsc .. . . Con i,b Z'b'mewCitiml - Contro6 Chm<ecCiti<. Ccmbo4 Ch'mrxCrtia Cw.coF Obwkved Pxppcy0 . flxqwfW. .. OF.c.r:cd Lxp«1cil. . Exf nal. . . Ob.vv<d Fqr,-bd .. .. p.Qa.-md . .. -DeIh 17extiY: .. De.Hn SMR Dathe &.\iR' DaeNu UoeOU SMR DeNh~ SMR' lZr" . DuOU. ..S_NR DM6+ .. SMR' NI Qmcn. 140 113.41 1.23' 122.70 1.14 98 73.19 1.34' 77.65 1.26' 42 40.22 1.04 45.05 0.93 Lun` C.acer 51 13.14 3.88' 18.01 2.83" 31 9.25 3.35' 11.63 2.6"F 20 3.89 5.14' 6.38 3.13' F/oPS+ew C.nmr 17 14.76 1.15 28.79 0.59 15 9.76 1.54 19.06 0.79 2 5.00 --- 9.73 ---- Sromsch C~r 29 19.18 1.51' 31.52 0.92 21 3.58 1.55 20.50 1.02 B 5.60 1.43 11.02 0.73 Iiver C.neer 21 52.92 0.397 22.74 0.92 14 33.66 0.42 13.64 1.03 7 19.26 0.36 9.098 0.77 Other Cew<n 22 ___ ____ ___ ___ 17 ___ -- _._ ___. 5 -- ...- ___ ___ Note: 'P < 0.05 'P < 0.01'SMR wn not nkolad w6en'Obeavei Dmh.^ wo < 5, - 2 - 8Zti£8L 1.80Z M M M M M M = = M i = i M M M M = = r

i mm r = m..= m.. m.. .. .. .. i.. .. ... mm Table 2. Standardized Mortality Ratios of Malignant Tumors in Male Tar Felt Workers with Different Exposure Levels fth-s,W«ura Wott n,w sa~u~txP~;vQk a,a, ... . ikeEixp~ .. u•ork n~ ,,,~ah~e' . .. , 'suon"aw.. . .. . Sbnd.idirxd '. Madivi.+-~ized . . Smd.rd'acd Ma3ium-c'acd . .. ... S mdW$ad. Medinm-r'ac . .. . . CmW6 .'. (Jhim.w Cmar - CmtroM Chiwee Cilia . . Cao4vM .. . . [;h®e. e CRin . . Cqnenf . ...oelqval . 8ipem«I .. . . ~Pcnui oMbrvw L,a'a.ZCd . . rx~caca . (ihav~a P,<re--ka . ... i~1?a'lcd . : DdN llntL. IkW. Sh¢l . Dutb S.'.1R' OnOx bcatlv S V.R Chat6s S.SfR' ll~ L"-.Or S.412 . PcaW SMR' AO Cancen 86 59.95 1.44' 64.65 1.33' 29 24.20 1.20 26.97 1.08 25 29.53 0.85 31.09 0.80 Lwg C.ocer 32 7.07 4.53° 9.53 3.36° 11 2.57 4.282 3.91 2.82' 8 3.51 2.28 4.57 1.75 E-Ph^8e+ C.ecer 13 7.35 1.77 14.71 0.88 1 1.32 •--- 6.53 --- 3 6.09 --- 7.55 ---- Bmmnch Gne<r 18 10.40 1.74' 16.682 1.08 6 3.65 1.64 6.74 0.89 5 5.15 0.97 8.22 0.62 liverC.n«r 13 26.75 0.49 11.88 1.09 5 12.81 0.40 5.35 0.93 3 13.36 --- 5.59 -- Olhcr Canccr. 10 _._ ____ ____ ___- 6 ._ 6 Note: 1P < 0.05 tP < 0.01 'SMR wm nut nlathted wheu'OWetved Deathn' wr < 5. - 3 - 6Zti£81b80Z

I Table 3. Interaction of the Effects of Tar-Exposure and Tobacco-Smoking on Lung Cancer Death Rates (in 1/100,000) of Male Workers Tar ESZposure Smoking Obsen•ed Person- Years Deaths Death Rate BR Value 95°le C.I. 15755 1 6.35 1.00 + 33737 5 14,82 2.33 (0.29-18.76) + - 16621 10 60.16 9.47' (1.78-50.77) + + 37601 41 109.04 17.16' (4.08-72.79) Note: 'P < 0.05 2P < 0.01 N O O ~ -4 O G! - 4 - ~ ca O I I I I I I I I I I I I I I I I I I