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[그린피스웍크숍.En] 일반인과노동자의 방사능피폭기준

Radiation
Briefing on radiation levels for members of the public and workers
Jean McSolely
Greenpeace

INTRODUCTION

1. In Australia the permitted maximum radiation exposure from man-made
sources of ionising radiation, excluding medical sources, presently
stands at 5mSv per annum for members of the public and 50 mSv for
workers. Health studies on populations exposed to ionising radiation,
at levels previously thought to be “safe”, have shown the presently
recomended exposure levels to be too high by at least a factor of 3.
Recent work on nuclear reprocessing workers has indicated a severe
underestimate of the risk of offspring contracting leukemia via
genetic damage to the father’s sperm. A number of experts have now
recommended that in Austraila public exposure levels be reduced to
0.5mSv. This will then brimg public exposure levels closer to those
in other countries(US 0.25mSv, West Germany 0.3mSv and the UK 1mSv).
For workers the level should be reduced to 15mSv in the short term
with 5mSv to be phased in over the longer term.

PERMITTED LEVELS
2. Over the years the permitted levels of radiation for both workers
and members of the public have been steadily reduced, not increased.
The primary reason for this is the increased risk of cancer and
genetic impact indicated in various health studies on a) A & H Bomb
survivors b) patients who received radiation treatment for illness and
c) worker populations in mines and nuclear reprocessing plants.
3. Radiation limits apply to all man-made sources of radiation
excluding medical exposure(where it is always assumed the benefit
outweighs the risk). The levels recommended by the International
Commission on Radiological Protection(ICRP) are as follows:
WORKER PUBLIC
1900 100 mSv per day No limit set until 1952
1925 5,200 mSv per year
1934 3,600 mSv per year
1950 150 mSv per year 1952 15 mSv per year
1957 50 mSv per year 1959 5 mSv per year
1990 20 mSv per year 1987 1 mSv per year
4. The ICRP’s nost recent report contains only draft recommendations
on worker doses, which might be ratified or changed at a later date.
The limit of 20mSv for workers applies over a 5 year period, i.e. over
that time doses should not exceed 100mSv, with the level of 50mSv
still permitted in any single year. For members of the public the
ICRP recommended that the lifetime dose from radiation exposure be
70mSv(assuming a 70 year lifespan this implies a limit of 1mSv per
annum). The limit of 5mSv in any one year wtill exists to allow for
unexpected increased levels above normal rates.
5. The higher 5mSv level allows for radiation doses which would be
received if there were a major accident. Allowing members of the
public to receive this increased exposure permits polluting utilities
to remain within the law and exempts them from compensation claims.
6. Although the ICRP has no legal status in any country its
recommended limits are usually accepted as the maximum doses which any
country will allow for workers or public. However, over the years
there have been many comerms regarding the ICRP’s industry bias as a
number of its members are answerable to any Government, has caused
fears as to its independence. It is because of this that a number
recommended levels of radiation for the public and workers which are
lower than the ICRP limit. For example, in the US public levels are
set at 0.25mSv per annum and in West Germany at 0.30mSv. The UK
applies the ICRP limit of 1mSv(with a subsidiary limit of 0.5mSv form
any single installation).
7. Since 1987 the UK National Radiological Protection Board(NRPB) has
recommended a limit of 15mSv per annum for nuclear workers. This
recommendation followed the 1987 meeting of the ICRP at which the
latest A & B Bomb data was discussed. At that time the ICRP said they
would wait before issuing new guidelines.
8. Since 1987 the US Committee on the Biological Effects of Ionising
Radiation(BEIR) have also published a report which shows that the risk
from radiation is 2-3 times more damaging than once thought. The
report comcluded that there, no level of ionising radiation below
which damage will not occur i.e. there is no safe level of radiation.
Given all of the above it is not unreasonable that the Australian
Government should do as other countries thave done and recommended
lower levels of exposure for both the public and workers.
9. Under the old ICRP recommendations, exposure at the worker limit
of 50mSv for workers was considered to produce a risk of fatal cancer
of 1 in 2000. Exposure at the limit is now recognized to produce a
risk of 1 in 500, while a dose of 20mSv produces a risk of 1 in 1250.
The UK Health and Safety Commissions considers that a risk of 1 in
1000 is the maximum that can be tolerated in industry.
10. The ICRP’s recent recommendation on worker doses noted, but did
not fully consider, the recent UK report on leukemia rates in the
children of Sellafield workers. This study has changed the world view
on radiation standards. Genetic risks have constantly been
underestimated by the nuclear industry as previous
studies(predominantly A & H Bomb survivors) had not indicated any
impact in this area. This is mainly because of a five year delay
between the bombings and the beginning of the health study(most of the
genetically damaged had been born and died before anything had been
done). However, it is a fact that genetic damage has always been
recognised as an effect of radiation.
11. The UK study found that for workers with a cumulative working
dose of 100mSv, or for those with a dose of 10mSv prior to conception,
the risk of fathering a child with leukemia is 6-7 times normal(rising
7-8 times for the 10mSv prior to conception). Obviously past levels
of radiation exposure to workers were not stringet enough in terms of
damage to worker offspring. New risk estemates for the next advisors
in the UK are now considering recommending a radiation dose limit of
10mSv, with a view to reducing this to 5mSv as soon as is reasonably
practicable(this is lower still than the NRPB’s 15mSv recommended
level).
12. As the permitted level here is 50mSv the Sellafield findings
should be of concern to Australian workers. A number of workers in
the mineral sands and uranium mining industry presently receive doses
over the recommended UK level of 15mSv. The jobs which entail
receiving the highest radiation exposure usually carry the highest
wages. Quite what will happen to these workers when and if they
exceed the new ICRP “recommended” level of 100mSv in five years is not
known. To allow them to continue to be exposed above the 15mSv level
is to put them at a risk higher than that suffered in other hazardous
industries.

16. Monitoring can be undertaken in several ways. Special devices
can be in homes and gardens to measure radon levels. Experiments can
be very detailed, involving the analysis of vacuum bags from homes in
areas thought to be at risk. Monitoring of locally grown foodstuffs
and animals, as well as water, can be undertaken. In some areas, near
nuclear facilities, members of the public are measured for
radioactivity and are asked for blood, urine and faecal samples(this
should be done as a matter of course for workers). Autopsy samples on
still-born and miscarried children(as well as placenta), along with
analysis of organs from adults, can be done(as in the case of the area
around the Sellafield nucelar plant.)

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