Relative Risk Factors Five and More Years After Start of Uranium Mining
Radon Exposure Category (WLM)
Average Exposure (WLM) [1]
Lung Cancers Observed [2]
Lung Cancers Expected [3]
Excess Lung Cancers
EC = [2] - [3]
Relative Risk Factor (Excess cancers per WLM per 1000 cancers expected) RRF = ( EC x 1000 ) / ( [1] x [3] )
under 120
60
5
1.84
3.16
29
120-359
240
9
1.99
7.01
15
360-839
600
13
2.52
10.48
7
840-1799
1,320
11
2.26
8.74
3
1800-3719
2,760
20
1.27
18.73
5
over 3720
4,000
10
0.41
9.59
6
Total
900
68
10.29
57.71
5.7
Notes
The raw data for this table are exactly the same as the data for Table 1, dealing with the Colorado Plateau miners..
See note 2 from Table 1. The same observation applies here.
The Relative Risk Model, used here, measures the excess cancer as a fraction of the expected incidence. It assumes that any increase in this fraction, the relative excess in cancer, will be proportional to the excess radiation exposure. The Relative Risk Model is used more often than the Absolute Risk Model; see Tables 3 and 4 -- Exhibits 6 and 7 -- for example.
The first column and the last column are the important ones to study. Notice that the overall average of 5.7 excess cancers per WLM per 1000 cancers expected tends to ignore the low-exposure data.