HEALTH
& SAFETY
FOOD IRRADIATION AND BIOLOGICAL EFFECTS
1:
Why
is there so much delay and hesitation in approving irradiation of food items?
There
is a delay but no hesitation in approving irradiation of food items. Government
of India has in principle accepted irradiation processing of food stuffs and
also constituted an Apex Body namely National Monitoring Agency under the
Ministry of Health to oversee all aspects in implementing this technology in
India. The delay came in finalizing the rules under the Atomic Energy Act to
control the food irradiation process and amendment of PFA act for including food
irradiation technology and labelling of irradiated foods. Now the rules under
Atomic Energy Act have been approved and published in India Gazette March 1991.
As and when the PFA rules are also published, commercialization of this
technology will begin in India.
2:
When
food is irradiated for preservation and for preventing sprouting, have any
harmful chemicals or radicals been identified?
Food
irradiation is known as a cold process, since the energy imparted to the food is
very low, the chemical changes resulted are also very minimal. More than 40
years of intensive research could not identify any unique radiolytic product,
making it difficult to distinguish irradiated food from non-irradiated one by
simple chemical analysis. The free radical produced are also short lived
depending on the medium in the food. More water content gives faster dissipation
of the radical.
3
It
is true that irradiation of food stuff prevents the growth of bacteria. But
irradiation of food if not followed by proper post-irradiation handling such as
packaging and storage at proper temperature there is bound to be re-infestation
nullifying the beneficial effect. Unless we have proper handling, storage and
transport system, replacing the old methods, we cannot introduce this technology
for items like wheat, fish, etc.
4:
Food
preservation using radio isotopes is demonstrated: cost and safety-wise how it
compares with present conventional method? If it has a potential for benefit why
is it not being used in India?
Use
of radioisotope for preservation of food has many advantages over the
conventional methods. Cost and safety of this processing is comparable with any
other food processing methods now used. Additional built-in safety is assured
because one has to deal with radioisotopes. The benefit and advantages of the
process outweigh the cost due to value addition on the product. It is a need
based technology applied where there are economic benefits. That is the reason
why India presently has considered clearance of three items, spices, onions and
potatoes which are economically important commodities.
INTERNAL
EXPOSURE DOSE AND DOSE COMMITMENT
1:
What
are the different criteria to be taken into account before fixing dose for a
particular organ of human body ?
Criteria
for internal dose are:
 |
Physical properties of the inhaled / ingested material. |
|
Radiological properties e.g. alpha emitters are weighted 20 times for
equal energy released in tissue compared to gamma and beta emitters. This factor
is referred to as radiation weighting factor {Quality factor}. Energy released
in a tissue is multiplied by the radiation weighting factor as the first step of
normalization. |
|
Radiation dose in case of extremities like hands and feet; skin and lenses of
eye is averaged over the weight of tissue.
0.5 Sv or 0.15 Sv is the permissible limit for the tissues. |
|
Different tissues in which dose is delivered, depending on the radiation damage
to the individual as a whole or to subsequent generations, are given different
weighting factor. For example, radiation dose to skin. Dose received is
multiplied by the appropriate weighting factor as the second step of
normalization and weighted doses are added up to arrive at the total effective
whole body dose.
|
2:
How
the equivalent dose to various organs of the body from non-uniform irradiation
is related to whole body limit for uniform radiation?
This
answer is included in Answer 1.1 i.e. after applying proper radiation weighting
factor {Quality factor} for the radiation type and the tissue weighting factor
for the organs, these become comparable.
3:
Are
we strictly following ICRP standards for limitation of dose? Can these be
modified according to different environmental conditions ?
We
are following ICRP limits for control purposes; the dose calculations are made
in case of suspected exposures, based on local conditions like meteorological
and climatic conditions, eating habits etc. in order to arrive at a correct
value for dose.
4:
ICRP
has brought out reports reducing permissible equivalent dose limits for
occupational personnel. How will it affect on-going radiation/nuclear
activities?
For
the ongoing programmes the
reduction of exposure potential has been achieved in stages (0.04 Sv in 1991,
0.035 Sv in 1993 etc.) so as to bring down the exposures to 0.02Sv/year. As it
is, dose contribution from operating our present plants is only a fraction of
their permissible allocation and these will require no significant modification.
Modifications are introduced in all future plants and where required even in the
older plants.
5:
The
ICRP has progressively reduced the dose limits. Does it mean that many of the
earlier exposures are highly unsafe ? If answer is yes to the above question, is
the country prepared to pay "radiation damage" compensation to earlier
workers. Are we not morally/legally bound to do so ?
Most
of the earlier exposures are within 20% to 30% of the then ICRP limits. Average
exposures are much less. These exposures are thus within the present safety
limits. The question of `Radiation damage' compensation payment arises when a
radiation related illness is brought to light. In case of other industries also,
workers are paid compensation for an accident or damage in the course of work
and not for the risk involved in the work.
6:
Synergistic
effects due to radiation and malnutrition are not yet revealed. Influence due to
total body/tissue size and metabolic changes are not large enough to recommend
separate limits for control purposes. In case of accidents and incidents,
separate individual calculations are made.
7:
Why
is a worker allowed to take dose exceeding the permissible value at the time of
accident ?
At
the time of accident, a worker is not allowed to get exposed, but he happens to
get exposed. However, under certain circumstances a worker may get over-exposed
but it will be once in lifetime and his life time dose remains within limit.
8:
What
is the immediate radiation risk for accidental exposures and daily exposures?
Accidental
or daily exposures with an immediate risk to life or health are very rare. Even
a disaster like Chernobyl has caused only 32 deaths.
Daily
exposures are controlled with occupational exposure limits and do not result in
any perceptive risk.
9:
When
we are exposed to nuclear radiation does it remain in our body ? If it is so,
how do we take out its ill effects ?
Radiation
does not remain in the body when exposed to external source of radiation. If
radioactive isotope are inhaled/ingested, these may remain in the body and
continue to irradiate the tissues. These can be removed by methods like isotopic
dilution i.e. drinking more water in case of exposure to tritium as water,
consumption of potassium iodide to prevent deposition of radioactive iodine,
administration of carbonate or bicarbonate to remove Uranium etc.
Radiation effects are also subject to repair mechanisms, either natural or similar to other illness medically influenced like bone-marrow transplant and the like
10:
In
calculating the dose to the population, whether separate consideration is taken
for children below 5 years and about pregnant
ladies ?
No
separate considerations are made for children or pregnant women while fixing
limits for population exposure. The recommended limits for population exposure
are at a safe level even for children, born and unborn.
11
When
safety recommendations are followed, the dose to members of public from waste
disposal at a given time has to decrease with time due to radioactive decay.
12:
On
an average, how much radiation dose a patient receives in taking an X-ray for
chest? How much risky is it? What damage can it cause to him ?
One
X-ray examination results in a radiation dose of about 200 microSv to
the patient. This is not expected to give any immediate damage at all, and makes
a very insignificant contribution to cancer incidence or genetic risk (1.2x10-5
).
13
C-14,
K-40, Ra-226, Th-232, Th-228 Uranium and isotopes of Radon are some of the
radioactive isotopes present in the body and irradiate our body. In addition,
cosmic rays also irradiate our body. Total radiation dose is 2.4 mSv and risk to
life is 7% per Sv.
14:
It
is reported that about 300 workers from TAPS, MAPS, RAPS and NFC are
hospitalized due to diseases caused by over exposure - what will be the official
reply for this?
The
report is not correct. The BARC Hospital at Mumbai has less than 300 beds and
caters to about 90,000 persons in a year. No DAE employee has been treated in
the hospital for illness due to over-exposure.
POLICY AND INFORMATION
1:
2:
Persons
working with radioactive materials are aware of the dangers of radiation and
take necessary precautions against them. Theft cases of such a nature that you
mentioned are always investigated and necessary security measures are taken so
that this does not recur; unfortunately these pencils have a shining surface and
attract the attention of persons in the
hope that it is something valuable.
3:
Any
company or industry handling radiological
materials should follow the prescribed procedures as approved by Atomic Energy Regulatory Body. This practice is generally followed by all including nuclear power stations at present. No breach of practice has been noticed so far. Adequate action will be taken as and when found guilty by way of
restraining the operations or shutting the
unit down or cancelling the license for
the company.
4:
We
are not aware of any international law to arrest the abuse of a nuclear site
during any dispute or war. However while selecting the site this aspect is taken
care of. Of late, some countries have gone for agreement of not attacking each
other's nuclear installations.
5:
Health
risks associated with the production of electricity from various sources have
been analysed in detail by various agencies. Some estimates ("Risk and
Benefits of Energy systems" proceeding series IAEA, 1984) of fatalities per
1000 MWe generation per year are as follows.
Fatalities/1000 MWe
|
Source |
Occupational |
Total
Including Public |
|
Coal |
2.5 - 7.4 |
19-60 |
|
Oil |
0.3 - 2 |
6 - 19 |
|
Wind |
3.6 - 4.3 |
4.2 - 6.0 |
|
Hydro |
1.5 - 2.6 |
2.6 - 4.2 |
|
Natural
Gas |
0.16 - 0.5 |
0.2 - 0.5 |
|
Nuclear |
0.5 - 1.6 |
0.6 - 2.1 |
As
compared to other industries and power generation systems, the risks of nuclear
industry are better understood and hence are being effectively controlled. The
nuclear industry has set a goal that the risks associated with utilization of
atomic energy for power generation are only a small fraction of similar risks
elsewhere. Since this risk is to be reckoned from both normal operation as well
as accident conditions, very stringent safety standards have been established in
siting, construction, design and operation of nuclear facilities. The United
Nations Risk assessment studies have shown that the health hazards due to
chemical industry and thermal power stations are much more than that caused due
to environmental pollution from nuclear industries.
6:
7:
Nuclear
Power Corporation of India Limited has created a Directorate of Environment and
Public Awareness to educate and disseminate authentic information to the public
about various aspects of harnessing nuclear power. In association with Publicity
Division of DAE, NPCIL is holding various exhibitions, seminars, open
discussions on the above subject.
A
mobile exhibition is being put up to be taken
around the various villages around our nuclear installations to educate the
people around the installations about the
benefits of nuclear energy and steps taken
to ensure its safety.
8:
Normal
police action as per the law of the country has been taken in such cases also.
9:
No
worker has been exposed more than the permissible limits set by AERB and ICRP
during the operation of Indian reactors uptil now, so the question of comparison
does not arise.
There
is no provision for compensation due to radiation exposure anywhere in the
world. It is understood that exposures contained within the limits prescribed by
ICRP do not cause any damage and are taken care of by the normal repair
mechanism of the human body.
10:
In
all nuclear power stations, hospitals are provided not for radiation victims but
for welfare and medical treatment of all personnel working in the organisation.
However
personnel decontamination centres are provided to help the radiation victims and
arrangements for treating them as required in the existing hospitals.
Arrangements exists for transferring patients to Mumbai and some other centers
for specilized treatment if warranted.
11:
No
person has been contaminated beyond the permissible limit. However external
contamination can be removed by thorough wash, scrubbing and clinical cleanup
with chemicals. They are found successful.
12:
13:
We
are aware of the above reports. Their truth is yet to be established.
14:
15:
16:
Government's
policy is to use atomic energy for welfare of people and the society. And so is
that of Department of Atomic Energy. Scientists and engineers are trying their
best to bring out the fruits of this technology to the doorsteps of the people.
It is a healthy situation that this matter is being discussed not only among the
technologists and scientists but also among the society. It is the society which
has to decide what risk they can accept for extracting the benefits. But we
should be cautious enough in giving unauthentic publicity to the people so that
they are not swayed away and are deprived themselves of the benefit of the power
of atom.
17:
The
accident at TMI was a result of operator's wrong action. While this did result
in the partial melting of the core but no release of radioactivity into the
environment took place because of the containment. The accident at Chernobyl in
1986, the worst in the history of nuclear power, is the one where release of
radioactivity did take place. This was due to wrong design and adoption of wrong
operating procedures and absence of proper containment building as is in vogue
elsewhere.
The
design of Indian reactors are of different type and are with containment and
operating procedures are much more stringent; as such the possibility of a
severe accident is very remote. Knowledge gained from these accidents is being
applied as and where required.
18:
From
time to time, Publicity Division of DAE is bringing out the reports in this
regard. These reports can be obtained from DAE.
19
Health
Physics and E.S. Labs are not directly under the management of Nuclear Power
Corporation.of India Limited Their activities are monitored by Atomic Energy
Regulatory Body which is independent of DAE. and reports to Atomic Energy
Commission.