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Table 1. Some asbestos myths All forms of asbestos are equally hazardous All mesothelioma is caused by asbestos Cne asbestos fibre can kill A11 substitutes for asbestos are harmless Table 2. Concentrations of asbestos fibre in the occupational environment (estimated "averages' (fibres/ml/ across industries) Before the 1930s 1935-45 1950s 1960-71 1975 1980 much more than 100 f/mi more than 100 f/ml 100 f/ml 20 f/ml 5 f/mi 1 f/ml N Ll1 ~ ~ ~ ~ . .~ ~ O

Table 3. Proportional mortality from mesothelioma In the major cohorts of male asbestos-exposed workers Fibre type (and process) No. of Tota1 Deaths from Proportional cohorts deatha ResotheZ.ioara aaortality (t) Chrysotile Chrysotils with small proportion of amphibole - manufacture - textiles -nosite Mixed - shipyard work Crocidolite Kixed - insulation :'hrysotile with larger proportion of amphibole 5 6 2 3 2 3 5 2 5,062 3,925 1,622 871 1,077 653 3,055 926 11 25 26 25 31 43 235 77 0.2 0.6 1.6 2.9 2.9 6.6 7.7 8.3 * * * * Marked heterogeneity !V LJ1 iC7 S

Table 4. !lesothelioma in asbestos mining and milling Chrysot3le Amosite Csroc3dohEte (a) Number of men in cohort 10,939 3212 3430 (b) 'Av:rag.' length of follow-up 45 y 20 y (C) 'Average" exposure [(fibres/ml) x years) 700 15 10 (d) Number of deaths (all causes) 4463 648 423 (e) Number of deaths from mesothelioma 10 4 20 (f) Proportional Mortality Ratio (PMR) (100 (e)/(d)j 0.2 0.6 4.7 (q) 'Risk' per unit exposure f(f)/(a)) 0.0003 0.04 0.47 N U'I a 0

Tabl: 5. Lung cancer risks 3n 32 cohorts of asbestos workers (Standardized Mortality Ratios jSHRSJ with confidence Intervala jCIsJ) t3bre typo and proc.ss No. of Deaths from cohorts lung cancer S!!R (CI in brackets) 2%sTsotil. (solely or predominantly) manufacture, cement 4 62 1.02 (0.78-1.31)' mining/milling, gasmask filters, friction products 5 406 1.23 (1.12-1.36) 'u-Tsotils and asphibole cement 7 351 1.56 (1.40-1.73)b manufacture (retirees) 1 77 2.71 ( 2.14-3 . 39 ) Aaosit. ~ mining/milling 1 26 1.38 (1.08-2.14) Amosito and crocidolits mining/milling 1 10 2.22 (1.06-4.09) Crocidolite gas mask assembly 3 33 2.09 (1.44-2.93) mining/milling 2 118 2.47 (2.04-2.96) ^lZtilss chrysotile 1 59 1.99 (1.51-2.57) chrysotil: and amphibole 4 377 1.75,(1.58-1.94)b nsuistion chrysotil• and amphibol• 1 397 4.24 (3.83-4.67) amphibol: 2 84 4.80 ( 3 .83-5 . 94 ) a Except where heterogeneity is indicated, the degree of confidence is 95%. b Because of heterogeneity, the true 95 % CI is rather wider. - 13 -

Table 6. Risks of excess Zung cancer resulting froar occupational asbestos exposure Chrysotfle Xixturesi amos1te° Crocidolite;d taxt3.lesf slope 0.05 0.2 0.5 1 (Zncrease in SMR per 100 (fibres/ml) x yearsj Lung cancer SMR - 1+[(slope) x(exposure)j/100 Excess risk - (slop.) x (exposure) x (background) Examales Exposure: 4 (fibres/ml) x years (e.q. 8 years at 0.5 f/ml) , lung cancer SMR 1.002 1.008 1.02` 1.04 excess risk as % of background 0.2 0.8 2 4 excess risk where background is 5% 0.0001 0.0004 0.001 0.002 where background is 10% 0.0002 0.0008 0.002 0.004 Exposure: 20 (fibres/mi) x years (e.g. 20 years at 1 f/ml) • lung cancer SHR 1.01 1.04 1.10 1.20 excess risk as % of background 1 4 10 20 excess risk where background is 5% 0.0005 0.002 0.005 0.01 where background is 10% 0.001 0.004 0.01 0.02 a b c Solely or predominantly chrysotile, not in textiles. Mixturea of amphibole and chrysotile, not in texti2es. Amosite fnsulation materials; rough approximations. N CJ9 ~ ~ d Solely or predominantly crocidolite. ~ e Chrysot3le, or chrysotfle with amphfbolea. -~J .~ C - 14 -