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102
G. Berry, J. C. Gilson, S, Holmes, H. C. Lewinsohn, andS. A. Roach
Asbesi
Table 2 Summary of exposure at factory
Exposure factors
Year started at factory 1933-35 1936-40 1941-45 1946-50 1951-55 1956-60 1961-65
Workers first employed before 1951
Total
With signs
11 7 50 21 28 u
_93 23 __
----
Workers first employed after 1950
Total
With signs
.. ,
-- __ ,
109 75 13
___
___ ___
22 6 2
50-
V)
1 t0'
I 30tj r !0-
s
g n-
Maximum annual time-weighted average concentration (f/cm#) <5 5-9-99 10-19-99 20-50
1 38 70 73
Cumulative exposure* (f-yr/cm*) <50 50-99 100-149 150-199
200-249 250-549
5 25 36 44 39 33
Time since first employed at factory* (yr)
<10
1
10-14
0
15-19
17
I 20-24 25-29
65 51
30-39
48
Age* (yr)
<40
40-44
45-49
I
I
50-54 55-59 60-72
3 5
22 34
52 66
0 11 9 82 26 92 27 12
1 36 6 95 12 52 17 14 11 ___ 15 --
09 0 74 12 J-114 19 16 15
0 36 0 25 8 31 13 35 22 33 19 37
l 9 18 2
4 12 13 1
--
1 16 13
0 3 4 4 11 8
U
0J
Fig. 2 asbesti
interp expos1 with i havei dusty
Thf presse foragi was r 1950 i within Table ive e>
Table
Total
182 62 197 30
Cumuta.
For those with signs, these are calculated up to the first occurrence of the signs.
Table 3 Number ofmen with crepitations recorded by factory medical officer or by Pneumoconiosis Medical Panel
Examiner and opinion
Pneumoconiosis Medical Panel
Yes No Total
Factory medical officer Yes No
51 27 31 268 82 295
Total
78 299 377
in whom crepitations were heard at the factory but were not heard by the PMP.
RELATIONSHIP BETWEEN POSSIBLE ASBESTOSIS AND CERTIFICATION
Except for the one man who was certified after
death, and had not been seen in the factory medical department within the previous 10 years, all the certified cases were also in the possible category. An analysis, using life-table techniques, has been carried out on the interval between suspicion and certification. The results are given in Figure 2, which shows the cumulative percentage of certified cases plotted against time since suspicion; 25% became certified within 15 months of suspicion and 50% within 3-5 yr, Of 19 men who were uncertified after five years' follow-up since first suspicion, only one was subsequently certified in, on average, a further two years' follow-up.
RADIOLOGICAL FINDINGS, LUNG FUNCTION AND EXPOSURE
The profusion of small opacities and bilateral pleural thickening have been related to cumulative dust exposure (Table 4). Again, these data cannot be
(f.yrlcm
First en <25 25-4 50-2 75-9 100-1 125-1 150-1 175-1 200-2 225-2 >250
Total
First en <25 25-4 50-7 75-9 100-1 125-1 >150
Total
Averaj cases be tAt leai