Environmental Engineering Reference
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all workers has decreased by 23%, mainly due to the reduction of average duration of the case by 28%
and in terms of numbers of days in hospital by 44%. In the irst period, sickness of drilling workers
was 44% higher than among others; in the second period, it was not a reliable difference in this index.
In general, these results suggest that it is a great possibility that correlation between concentra-
tion of radon decay products in the working sites and sickness of breathing organs in terms of days
of disability of miners took place especially for drilling workers, that is, for the group with the
higher intake.
15.10.3.3
Comparison of Tadjikistan Data with Data from Other Epidemiological Studies
Analyses of many epidemiological studies are presented in Lubin (1994) and BEIR VI (1999)
together with advantages and disadvantages in every study. It was also mentioned, especially in
Ruzer (2001), that the uncertainties in dose assessment are very high and no data are available on
the individual dose of miners or at least for different groups of miners.
In this sense, data on nonuranium miners in Tadjikistan present a new approach to the problem:
•
A large diversity in terms of radon progeny concentration for different groups of miners,
with especially high concentrations for the drilling group, was pointed out.
•
The parameter of physical activity, FAL, differs substantially within groups of miners,
with the highest for the drilling group.
•
As a result, the drilling group had the highest intake among other miners.
•
Both lung cancer mortality and lung sickness of miners were highest for the drilling group.
•
For the irst time in such studies, direct measurements of the activity (dose) in the lungs of
miners were used.
From these results, the conclusion should be drawn that it is incorrect to consider miners as a uni-
form cohort in the risk assessment study, both from a dosimetric and epidemiological point of view.
15.10.4 q
uality
oF
d
osiMetry
and
tHe
r
isk
a
ssessMent
For
M
iners
: s
oMe
a
sPects
oF
tHe
c
oMParison
oF
a
“j
oint
a
nalysis
oF
11 u
nderground
M
iners
s
tudies
”
and
a
s
tudy
oF
n
onuraniuM
M
iners
in
t
adjikistan
The direct measurement technique presents an opportunity to measure directly the deposition
of radon decay products in the lung and, due to the correlation between alpha-dose and gamma-
activity, to determine the absorbed dose to the lung tissue.
Direct measurement also provides important information about the correlation between con-
centration in the air and activity in the lung. This transition coeficient called FAL is a product of
minute volume rate and deposition coeficient. It also plays an important role in dosimetry of non-
radioactive inhaled particles because it does not depend on radioactivity but depends on physical
activity and particle size distribution.
The accuracy of dose assessment by direct measurement is the highest achievable (35%-40%
uncertainty), and for this reason it presents an opportunity to assess the optimal uncertainty in the
dose under real conditions and, consequently, the uncertainty in risk assessment.
In Lubin (1994), a joint analysis of underground miners in China, Czechoslovakia, Colorado,
Ontario, Newfoundland, Sweden, New Mexico, Beaverlodge, Port Radium, Radium Hill, and
France was presented. The objective criteria for inclusion in the study of joint analysis were
•
A minimum of 40 lung cancer deaths
•
An estimate of Rn progeny exposure in WLM for each member of the cohort based on
historical measurements of either Rn or Rn progeny
Let us look at both these criteria from the point of view of reliability (uncertainty) in the risk assessment.
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