Radioactive Aerosols - Aerosols: Measurement, Dosimetry, and Health Effects - page 386

Our measurements in mines, and especially the direct measurement of radon decay product
activity in the lungs of miners, suggest that there is no correlation between the data on measured
concentration as is measured routinely and the activity (dose) in the lungs of miners.
The signiicance of the uncertainty in risk estimates in this case pertains not only to the abstract
metrological factors but also to the economic factors. Risk estimates are directly related to the per-
missible concentration in mines and therefore to the atmospheric controls, ventilation rate, predicted
health effects, etc.
On the other hand, it will be shown through these studies that the radon decay product concentra-
tion, together with the work load, directly correlated with the lung sickness of miners, which in turn
correlated with the economic factors.
15.4 DIRECT MEASUREMENT OF ACTIVITY IN THE LUNGS:
PROBLEMS WITH PRACTICAL APPLICATION
When I studied dosimetry, the idea and the resulting analyses to correlate the absorbed dose from
alpha-emitting radon decay products with the external body counting of gamma-emitting decay
products arose.
The importance of such a correlation was obvious. Alpha-radioactivity and the absorbed dose
from radon progeny in the lungs, the physical values directly responsible for the health effect due to
alpha-particles, cannot be measured directly. Alpha-particles have relatively high energy and a very
short range in tissue and thus can cause signiicant damage to cellular DNA in the lungs because of
this high linear energy transfer (LET).
On the other hand, the gamma-activity from two of the radon decay products in this decay chain
is measurable, and therefore, this correlation presented an opportunity to assess the absorbed dose
in vivo , at least in principle.
Model measurements were initiated using a human phantom and human body spectrometer in
order for quantitative external measurement of the radon progeny gamma-activity to be performed.
The amounts of radioactivity used in the phantom approximated the level that corresponds to that
in the lung from breathing the average air concentration in the mine atmosphere. Preliminary mea-
surements conirmed that such measurements are possible.
After the direct method was oficially approved by the Committee of Radiology of the Ministry
of Health of the USSR, the following statements were made:
1. The proposed method of estimating radiation effects from radon decay products con-
tained in the lung is in contrast to the generally applied method of indirect estimation
of the effect based on the measurement of concentration of radioactive aerosol in the
atmosphere.
2. The proposed method is original.
3. There is no doubt that it is possible to measure the intensity of the gamma-radiation of
radioactive aerosols deposited in the lungs of miners using high-sensitivity equipment
designed to estimate low concentrations of radioactive substances in human organisms.
The next logical step was testing the method under actual working conditions, that is, making
direct measurements on uranium miners. However, for me personally, this was to be a very dif-
icult task.
15.5 GEOGRAPHY AND UNDERGROUND CONDITIONS OF MINE REGIONS
The mining departments in which the study was conducted were located in the territory of the
former Soviet Republic of Tadjikistan and also partly in the former Soviet Republic of Uzbekistan
(Tashkent province).