Environmental Engineering Reference
In-Depth Information
as to practically exclude the entry of radon and its decay products through the lungs. The amount of
radon that entered the body from the skin was close to that in the irst series of experiments, that is,
the highest concentration. Contrary to the case of breathing, no difference in the biological effect
from the control group was found.
The comparative contribution of radon itself and its decay products is important in terms of
understanding what accuracy of measuring concentration of radon itself is important for dosimetric
purposes.
The measurement of radon concentration itself is practically important because it shows the
potential upper bound of danger associated with radon decay products, that is, with the equilibrium
concentration of radon progeny.
However, it does not represent the real qualitative assessment of the dose, because depending on
the shift of equilibrium the ranges of the dose can be of 2-3 orders of magnitude. The contribution
of radon will be substantial only in cases when the shift of equilibrium is small.
Still, the results of radon concentration measurements are practically important in cases when
preliminary assessment of the danger associated with natural radioactivity, especially in houses,
should be made.
Data on measurement of radon decay products in air by alpha and beta spectrometry are pre-
sented in Ruzer and Sextro (1997a).
Data on measurements of the unattached activity of radon progeny are presented in Ruzer and
Sextro (1997b).
15.10
DOSIMETRY
15.10.1 i
ntake
versus
e
xPosure
: P
roPagation
oF
tHe
u
ncertainties
in
d
ose
a
ssessMent
in
M
ining
s
tudies
Epidemiological studies of underground miners are the basis for estimating the risk of indoor
radon. Although there have been a number of studies investigating the health effects of exposure
to radon decay products in mines (the most recent compilation has been carried out by NRC 1998
[BEIR VI]), there are several unresolved issues in the assessment of the actual radiation dose to
the miners' lungs:
•
Lack of detailed spatial and temporal data on radon and radon decay product concentrations
•
Variability in the ratio between concentrations as measured by the standard inspection
procedure and as measured in the breathing zone
•
Variability in breathing rates and deposition coeficients for radon decay products in the
lungs for different types of work and among different groups of miners
•
Information not known about the use of respirators by different groups of miners
•
Very little data on the work itinerary (scenario of exposure) for individuals or groups of miners
The presence of such errors in the exposure estimates for miners has been widely recognized and
discussed in NRC 1998 (BEIR VI). In this context, it has been noted that concentrations of radon
and its decay products vary spatially and temporally within mines, although little data have been
published in this regard. In New Mexico mines, for example, information presented on dosimetry
documented extensive variation in the concentrations of radon progeny across various locations
within mines in Ambrosia Lake, New Mexico (BEIR VI).
It has also been pointed out in BEIR VI that exposure estimates for individual miners would
be ideally based on either a personal dosimeter, as used for low-LET occupational exposure, or on
detailed information on concentrations at all locations where participants in the studies received
signiicant exposure. For miners, information would be needed on the location where time was
spent, the duration of time spent in the location, and the concentration in the location when miners
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