28
costs of all the remediation activities are presumed to be enormous (NRC 2011).
The Czech government has committed to allocating nearly US$ 2 billion for the
remediation of legacy uranium mine sites through 2042.
It has to be emphasized that the uranium industry was developed at a time when
no strict regulations concerning eventual end-of-life management were in place.
4 Results of Epidemiological Studies
The assessment of cancer risks associated with exposure to ionizing radiation was
the aim of a number of epidemiological studies. Some of them concentrated on the
health effects in uranium miners which resulted from their exposure to radioactive
substances. A large proportion of the epidemiological studies were performed especially in the former Czechoslovakia, later in the Czech Republic, Germany, France,
the USA and some other countries. These studies of uranium miners and millers
included assessments of their exposure related to the uranium working environment. Most studies had difficulties in the reliable estimation of not only exposure
but also other factors, including smoking and other toxic substances encountered in
mines.
As early as in 1556, Agricola in De Re Metallica reported on a fatal respiratory
disease in miners. It was only in 1879 that this disease was identified as lung cancer.
Miners of uranium-bearing ores in the Ore Mountains of Central Europe were
reported to have an unusually high frequency of fatal lung disease.
In assessing the impact of uranium-related risk, researchers use different terms
and units depending on the aims of a particular study and their own preferences. It
is desirable to distinguish between the quantification of external penetrating radiation and internal exposure delivered mainly through inhaled radon and its progeny.
While external radiation can be evaluated using relevant operational quantities in
mSv, for the assessment of internal exposure, other units were introduced, namely,
WL and WLM.
The concepts used in assessing the risk caused by radon and its progeny are
based on disease incidence. In this context, it is important to understand the relative
risk (RR), excess relative risk (ERR) and working level (WL) as well as working
level month (WLM) which is often used to quantify the exposure to inhaled radon
and its decay products.
The relative risk represents a ratio of disease rates in exposed and unexposed
groups of persons (dimensionless quantity). This can be interpreted using the following example: if the cancer rate in an exposed population is, say, 8 out of 1000,
and in the unexposed population the rate is 4 out of 1000, the relative risk would be
8 divided by 4 or 2. The relative risk can be used to describe not only incidence but
also mortality. On the other hand, the excess relative risk is introduced as the relative risk minus 1. In other words, the excess relative risk represents the increase in
the risk of a disease compared to the background absolute risk in the absence of
exposure.
J. Sabol
costs of all the remediation activities are presumed to be enormous (NRC 2011).
The Czech government has committed to allocating nearly US$ 2 billion for the
remediation of legacy uranium mine sites through 2042.
It has to be emphasized that the uranium industry was developed at a time when
no strict regulations concerning eventual end-of-life management were in place.
4 Results of Epidemiological Studies
The assessment of cancer risks associated with exposure to ionizing radiation was
the aim of a number of epidemiological studies. Some of them concentrated on the
health effects in uranium miners which resulted from their exposure to radioactive
substances. A large proportion of the epidemiological studies were performed especially in the former Czechoslovakia, later in the Czech Republic, Germany, France,
the USA and some other countries. These studies of uranium miners and millers
included assessments of their exposure related to the uranium working environment. Most studies had difficulties in the reliable estimation of not only exposure
but also other factors, including smoking and other toxic substances encountered in
mines.
As early as in 1556, Agricola in De Re Metallica reported on a fatal respiratory
disease in miners. It was only in 1879 that this disease was identified as lung cancer.
Miners of uranium-bearing ores in the Ore Mountains of Central Europe were
reported to have an unusually high frequency of fatal lung disease.
In assessing the impact of uranium-related risk, researchers use different terms
and units depending on the aims of a particular study and their own preferences. It
is desirable to distinguish between the quantification of external penetrating radiation and internal exposure delivered mainly through inhaled radon and its progeny.
While external radiation can be evaluated using relevant operational quantities in
mSv, for the assessment of internal exposure, other units were introduced, namely,
WL and WLM.
The concepts used in assessing the risk caused by radon and its progeny are
based on disease incidence. In this context, it is important to understand the relative
risk (RR), excess relative risk (ERR) and working level (WL) as well as working
level month (WLM) which is often used to quantify the exposure to inhaled radon
and its decay products.
The relative risk represents a ratio of disease rates in exposed and unexposed
groups of persons (dimensionless quantity). This can be interpreted using the following example: if the cancer rate in an exposed population is, say, 8 out of 1000,
and in the unexposed population the rate is 4 out of 1000, the relative risk would be
8 divided by 4 or 2. The relative risk can be used to describe not only incidence but
also mortality. On the other hand, the excess relative risk is introduced as the relative risk minus 1. In other words, the excess relative risk represents the increase in
the risk of a disease compared to the background absolute risk in the absence of
exposure.
J. Sabol