Document rbg50Lpb0Ed8jXzr0kMgR50a

Roach ledical ill the egory. ! been n and ure 2, irtified . 25% in and irtified i, only ige, a ION lateral dative not be Asbestosis: a study ofdose-response relationships in an asbestos textile factory 103 Table 5 Regression coefficients of lung function indices and exposure in men first employed after 1950 Index Regressslon coefficient standard error (% predicted* f-yr/cm*) FEV1>0 FVC TLC TL - 0121 0-039 - 0-106 0-035 - 0-006 0-037 - 0-069 0-046 The predicted values were calculated from the reference relationships used in the factory; these relationships were calculated on men not exposed to asbestos and allow for age (a, yr) and height (A, m):-- FEVi., = 2-72 h-- 0 039 a + 0-48; FVC - 6-54 h - 0 032 a - 5-38; TLC - 7-24h - 0 028a - 5-43;TL = 32 0h - 0-20a - 170. Fig. 2 Time between suspicion and certification of asbestosis. interpreted as prevalences within the separate exposure categories because some of those subjects with radiological abnormalities were suspected to have asbestosis and weie therefore transferred to less dusty conditions. The lung function measurements have been ex pressed as percentages of predicted values allowing for age andheight (see footnote to Table5).The analysis was restricted to Caucasians first employed after 1950 (141 men) and the mean lung function values within exposure categories are shown in Figure 3. Table 5 shows the regression coefficients on cumulat ive exposuie. FEVi.o and FVC were significantly related to exposure but there was no evidence of a relationship for TLC; the relationship for TL could have arisen by chance but cannot be considered to be unimportant. THE INFLUENCE OF SMOKING Information regarding smoking habits was available for all except three of the men. The associations between the most recent smoking habits and crepita tions, possible and certified asbestosis, and small opacities, are shown in Table 6. The cumulative exposure was similar for each smoking category, as also was the time since first exposure to asbestos. For men first exposed after 1950 there are clear indications that non-smokers and light smokers are less likely to have any of the conditions. However Table 4 Radiologicalfindings and exposure Cumulative exposure (f.yricm) Total Profusion ofsmall opacities* 0U no ill First employment before 1951 <25 25-49 50-74 75-99 100-124 125-149 150-174 175-199 200-224 225-249 >250 Total 2 2 9 15 8 29 20 25 22 16 34 182 1 1 2 3 4 7 7 4 3 4 6 42 00 00 21 30 00 44 4i 40 52 30 10 2 35 10 First employment after 1950 <25 25-49 50-74 75-99 100-124 125-149 >150 5 31 59 37 26 22 17 1 10 9 14 2 6 4 00 20 53 11 50 30 22 Total 197 46 18 6 Jf2 or more 0 0 0 3 (1/2, 1/2, 1/2) 1 (3/3) 1 (1/2) 0 1 (3/2) 1 (2/2) 2 (1/2, 1/2) 5(1/2. 2/1, 2/1, 2/2. 2/2) 14 0 1 (1/2) 1 d/2) 1 (3/3) 1 (2/1) I (2/2) 0 5 . Bilateral pleural thickeningf U 0 2 4 0 1 2 2 3 1 4 19 1 2 2 3 0 1 0 9 Average of 4 readers; if the average was halftvay between two adjacent categories the reading was rounded downwards (there were 27 such cases between 0/0 and 0/1). tAt least 2 of the 4 readers recording bilateral pleural thickening.