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Windscale FAQs pdf - posted 3 Oct 2007 - updated 5 May 2008
Radiation, radioactivity and radioactive waste
Safety and security of radioactive materials
Medical radiation
Polonium-210
Mobile phones and power lines
Other topics
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What is radioactivity?
Some forms of matter, called radionuclides, are inherently unstable at the nuclear level. They are said to be radioactive because they lose energy in the form of radiation as they gradually become more stable.
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What is radiation?
Strictly speaking radiation is the transfer of energy through a material or through a space. However, radiation is the term commonly used to describe the energy released from radioactive atoms. This energy is more properly called ionising radiation.
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What are the different types of radiation?
There are two basic types of radiation: moving particles and electromagnetic rays. The nucleus of radioactive atoms may give off alpha and beta particles and neutrons. Electromagnetic emissions include gamma rays and X-rays. Gamma rays come from a radioactive nucleus; X-rays are more commonly produced by a machine. The particles, gamma rays and X-rays are all said to be ionising radiation.
Non-nuclear emissions from other parts of the electromagnetic spectrum (diagrams) (such as ultraviolet, visible and infrared light; microwave or radio frequency (RF) radiation, or lower frequency electromagnetic fields) are commonly described as non-ionising radiations.
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Why is ionising radiation dangerous?
The danger from radiation generally comes from its ability to ionise molecules in living cells and thus bring about biochemical change. If there is enough change in a living cell it may die, or its genetic information (DNA) may be altered. Most human cells die and are replaced regularly so cell death is only dangerous if it happens at a massive level. Alteration to DNA molecules in cells may however lead to cancer later in life.
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Is there a safe dose of ionising radiation?
Exposure to large amounts of radiation can produce acute effects such as nausea and radiation burns. There is also an increased incidence of cancer amongst survivors of the World War II atomic bombing. Most people however are exposed to very low levels of ionising radiation and there is not much evidence of harm to their long-term health. Because cancer is a very common illness it is very difficult to show a link with exposure to very low doses of radiation. To cope with this uncertainty, and to be on the safe side, it is assumed that there is always a small risk at low doses (based on an extrapolation of risks observed at much higher doses). Laws and rules are adopted so that prolonged low exposure should not produce a statistically significant increase in the usual occurrence of any cancer.
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How are people exposed to radiation?
Everyone on the planet is exposed, to slightly different extents, to a background of natural radiation. It arises from naturally occurring radioactive materials in rocks, soils, food and air. Because types of rock vary so too does the level of radiation coming from the ground; exposure thus depends on where you live. There is also an effect from cosmic radiation. Cosmic rays are more intense at higher altitudes so frequent flyers are exposed more.
Everyone is also exposed to man-made radiation. The most significant of these artificial sources is medical X- rays. There is also some exposure from industrial practices, such as weld radiography, and discharges from nuclear plants. There are still traces of radioactivity remaining in the environment from nuclear weapons testing.
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What is radon and why is it a problem?
Radon is a radioactive gas produced by radioactive decay of radium, which itself comes from the decay of uranium. The production of radon gas depends on the concentration of these radionuclides in rocks and soils. The distribution of radon is hence related to the underlying geology. Higher levels tend to be from very old rocks, usually granitic in origin. Radon gas from these rocks can be trapped in poorly ventilated buildings, thus giving the occupants a larger than normal radiation dose.
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What is cosmic radiation?
Cosmic radiation is composed of streams of particles coming partly from the sun and partly from outer space. This radiation interacts with the upper atmosphere to produce the cosmic radiation we experience at the earth's surface People who live at high altitude have a higher dose from cosmic radiation than those who live at sea level because shielding by the atmosphere is less. Aircrews and frequent flyers spend time at very high altitudes where the dose is even higher.
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What are the sources of medical exposure?
Most people experience medical radiation as a diagnostic tool through an X-ray (including dental X-rays). Alternatively radioactive materials may be given to patients when they are scanned to test an organ's function or to look for abnormalities. Radioactivity is also used to treat a number of illnesses (hyperactive thyroid glands and prostate cancers are just two of many examples).
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Do CT scans give more radiation than a normal X-ray examination?
Yes, radiation doses from CT scans are normally higher. CT scans are X-rays pictures of a slice through the body produced by an X-ray machine, which rotates around the body. Typical exposures take longer than a conventional X-ray examination. However, these scans can give better diagnostic information.
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Does having an X-ray or a CT scan make me radioactive?
No.
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What precautions are taken to ensure industrial and medical sources can't be lost?
Procedures for extensive and thorough record keeping must be demonstrated before anyone can be registered as a legal holder and user of radioactive sources. In the UK, medical radiation sources are subject to the same high level of surveillance as industrial sources.
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What are the laws governing the use of radioactive materials?
There are four main planks of the UK legislative system covering the use of radioactive materials. All of the regulations described are based on internationally agreed principles.
- The Ionising Radiations Regulations 1999 - enforced by the Health & Safety Executive (HSE) and the Ionising Radiations (Northern Ireland) Regulations 2000 enforced by the HSE for Northern Ireland.
These regulations apply to all work with ionising radiation. In essence the legislation places duties on employers that work with ionising radiation to protect their employees and others such as the public and those employed by other employers.
It should be noted that for some large users of radioactive materials additional controls (specified in licences) are put in place under the Nuclear Installations Act 1965, enforced by HSE.
- The Radioactive Substances Act 1993 - enforced by the Environment Agency in England and Wales and the Scottish Environmental Protection Agency (SEPA) in Scotland.
The Act regulates the holding, storage and use of radioactive materials, accumulation of waste and its disposal.
- The Ionising Radiation (Medical Exposure) Regulations 2000 enforced by the Department of Health for England, the National Assembly for Wales and the Scottish Executive in Scotland.
The regulations lay down basic measures for the health protection of patients against dangers of ionising radiation in relation to medical exposure.
- The Radioactive Materials (Road Transport) (Great Britain) Regulations 2002 enforced by the Radioactive Materials Transport Division of the Department for Transport.
There are some inter-related regulations, for example the Carriage of Dangerous Goods and Transportable Pressurised Equipment Regulations 2004. All are concerned with the transport of radioactive materials dictating what packaging, containers and labels must be used, how they are transported and the contingency arrangements that must be in place in the event of an accident. HSE enforces some aspects of the regulatory framewor, the Civil Aviation Authority for air transport and the Marine & Coastguard Agency for sea transport. All these follow similar rules so that a single package may be transferred from one mode of transport to another without relabelling or repackaging.
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Does irradiation of food make it radioactive?
No. Radiation doses used are huge but they do not induce any residual radioactivity in the food. The purpose of food irradiation is to kill harmful organisms. This process is also used to sterilise surgical equipment.
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Is solid radioactive waste still being dumped at sea?
No. This practice was abandoned in 1982 by international agreement.
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What radon reduction actions should be taken when a high level of radon gas is detected in a house?
Radon gas is present in all homes, from the minute amounts of uranium present in earth materials such as rocks, soils, brick and concrete. In most cases, the amount will be so low that no remedial action is justified. Above a certain level however, the householder may wish to apply one of several tried and tested methods to reduce radon levels in the house. The choice of method depends on the radon level and the way the houseis built.
For instance, increasing the ventilation, especially on the ground floor, will in most cases cause a moderate reduction in the radon level. It's a good idea to make sure that all airbricks are clear of obstructions. The most effective way to reduce high levels is to install a radon sump, a small void under a solid floor connected by a pipe to the outside. A small electric fan in the pipe continually sucks the radon from under the house and expels it harmlessly to the atmosphere. Modern sumps are often constructed from outside the house so there is no disruption inside.
There is no need to rush into any of these measures. The most important thing is to find out if there really is a problem. This can be done by looking at survey results from the area or by having the radon level in the home measured.
The Radiation Protection Division of the Health Protection Agency is the UK Government's adviser on Radon. To find out more, including how you could have the radon levels checked, visit http://www.hpa.org.uk/radiation/radon/index.htm and follow the links.
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Is there a radiation hazard to people who handle large volumes of mail which has been irradiated by the postal service to kill potential biological agents? Can mail (paper, paper clips, binder clips) that have been irradiated contain residual radioactivity?
Irradiating mail to destroy potential biological agents does not induce any radioactivity whatsoever in the mail (paper, paper clips, binder clips). The process would be the same as that used to kill harmful organisms in food and to sterilise surgical equipment. ) A simple analogy is that of having an X-ray taken, when of course the patient does not become radioactive.
Internet research suggests that irradiation is only being carried out in the United States on mail destined for certain Government offices. It is not thought that the practice is currently in use in the United Kingdom. The US Postal Service stated "Irradiated mail is sterile and poses no hazard. It is not and cannot be radioactive….We've found no medical or scientific link to irradiated mail and health-related complaints, such as itching and sneezing... and... the mail ... meets federal guidelines for potential carbon monoxide and ozone emissions. Irradiated mail... creates more paper dust" (31 Jan 2002.)"
While the mail and its contents do not become radioactive, any undeveloped photographic film carried in the mail would be spoiled by the large radiation field necessary to destroy harmful organisms. Anyone planning to implement mail irradiation would have to take this into account when setting up a programme.
Any views expressed in this answer are not necessarily endorsed by the Society for Radiological Protection.
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What happens when you breathe in radioactivity? Does the size of dust particles contaminated with radioactivity matter?
When a person inhales airborne radioactive particles, the particle size determines what fraction of them is deposited in the respiratory tract, and where, and what fraction is exhaled. Some deposited particles may be transported to the throat, swallowed, then leave the body in the faeces. Some may be transported to the lymph nodes. Some are removed as nose blows.
If the particles are soluble, some of the radioactive material will dissolve while they are within the body and will be transferred to other organs. It may then be excreted from the body. The degree of solubility of the particles, and other factors, will determine the pathways in the body taken by the radioactive material and its rate of transfer. The risk to the person is from the radiation emitted from the radioactive substance while it remains within the body. In these ways, particle size and solubility will affect the exposure of a person to radiation following inhalation of airborne radioactive particles.
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Do radioactive sources leak?
No, so long as they are handled correctly or not damaged.
Sealed radioactive sources are manufactured in such a way as to prevent
leakage.
A sealed source is a radioactive material that is either permanently sealed
in a capsule or closely bonded and in a solid form.
The capsule or material of a source is manufactured strong enough to remain
leak-tight under the conditions of use and wear for which the source was
designed and also under foreseeable mishaps.
Sealed sources are classified by an International Standard ISO2919 based on
test performance. These standards specify, appropriate to the type and
application, general requirements, performance tests, production tests,
marking and certification. Prototypes of sources are tested for resistance
to temperature, external pressure, impact, vibration, and puncture in
classes of increasing severity. Sources intended for a specific application,
e.g. industrial radiography, nuclear medicine, cancer treatment,
sterilisation of medical equipment, etc have to meet minimum criteria
outlined in the standard.
Radioactive sources used in certain medical applications or for tracer
studies, e.g. for environmental purposes, are by their nature open
(unsealed). These are governed by legislation so that during storage,
handling and use administrative and engineering controls are required to
maintain containment.
All sources are issued from the manufacturer with instructions for handling and storage. Sources are only sold to organisations that have appropriate regulatory authority to hold and work with such items. All sources are transported in appropriate types of transport containers in accordance with the current nationaland international transport regulations. The user is required to comply with regulations governing work with sources and their storage when not in use. These arrangements are subject to regulatory audit. Finally, when declared spent, sources can only be transferred to organisations that are authorised by regulatory authorities to handle and manage such wastes.
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Does spreading radiation dose over time change the risks to health?
At low doses and dose rates such as those normally experienced by workers or by the general public, the risks to health are assumed not to change with the time period over which dose is received. At high doses and rates, such as those used in radiotherapy, spreading the dose is used to reduce the risks of immediate harmful effects on healthy tissues by allowing a period for cell repair and recovery between treatment sessions.
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What is non-ionising radiation?
Non-ionising radiation is part of the electromagnetic radiation spectrum (diagrams) and has a long wavelength. This is important because long wavelength radiations do not have enough energy to "ionise" water (living cells are mostly water).
Non-ionising radiation sources commonly include radiotransmitters, mobile phones, microwave ovens, the sun, intense light sources such as lasers and infrared sources such as very hot objects.
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Will my mobile phone "fry" my brain?
No. While radio frequency radiations can cause heating, the power level of a mobile phone is so low that it cannot cause any noticeable heating in the brain.
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Do mobile phone base stations present a significant risk to the public?
No. The radio frequency radiation levels experienced by the public around a base station are much, much less than that produced by using a mobile phone.
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Will I get cancer from using my mobile phone?
This is extremely unlikely. Various reviews of the scientific evidence, carried out in the UK and internationally, came to the same conclusion - there is no evidence of a mechanism for causing cancer.
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Why have the experts warned that children may be at risk from mobile phones?
Although there is no evidence of a health effect, a group of independent experts (Stewart Report) recommended that a precautionary approach be adopted while further studies are carried out. This is because of children's developing nervous system, the greater absorption of energy in the tissues of the head and a longer lifetime of exposure.
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Should parents control mobile phone use by their children?
The Stewart Report recommends that that use of mobile phones by children aged up to 15 be discouraged until further research work has been completed.
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What effects have been observed from using mobile phones?
Some experiments have indicated changes in the electrical activity of the brain. These changes resulted in differences in cognitive tests (i.e. increased reaction times). Whether these changes result in long term health effects is not known but is doubtful.
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Can I find out where mobile phone base stations are located?
Yes, there are web-sites with maps of both rural locations (which are usually fairly obvious) and urban locations (which are not obvious). The most comprehensive web-site is http://www.sitefinder.radio.gov.uk/ maintained by Ofcom.
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What research is being undertaken to examine the potential health effects from RF radiation?
There are a wide range of studies being undertaken within the UK and Europe. The Mobile Telephone Health Research (MTHR) programme, which was set up as a result of the UK Stewart Report, includes work on epidemiology, biological effects, behavioural and measurement studies. The International Agency for Research on Cancer (IARC) plans to report in 2005 on additional work on mobile telephones. The International EMF Project, established by the World Health Organisation, is assessing health effects of exposure to electromagnetic fields in the frequency range 0 - 300 GHz. Collaborators on the project include the Health Protection Agency and the European Commission.
Link Mobile Telecommunications and Health Research Programme (MTHR)
The International Agency for Research on Cancer (IARC)
International EMF Project.
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Are the limits on RF field strength the same for all countries?
No. International guidelines are set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the majority of countries have adopted these as a basis for protection. However, some countries still use guidelines which are considerably more restrictive. Historically, the UK guidelines were higher than those in other countries, but it has now adopted the ICNIRP guidelines.
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What are examples of electromagnetic fields?
Electromagnetic fields include the Earth's magnetic field and fields from electrostatic charges, electric and magnetic fields from the electricity supply and radio waves from TV, radio and mobile phones, radar and satellite communications.
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What are the main contributions to people's exposure to power frequency EMFs?
The main sources of power frequency electromagnetic fields are the transmission, distribution and use of electricity at home, work and transport. Power lines, underground cables, substations and household electrical wiring are all sources of exposure. The field strength tends to fall rapidly with distance from the cables or appliances. People's exposure is variable and depends on lifestyle.
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What are the health effects of exposure to electromagnetic fields from the electricity supply?
Health effects depend on the strength of the field. Although fields from the electricity supply will induce currents in the body, including the central nervous system, they do not have enough energy to damage DNA. Below international guideline levels no health effects have been proved. However, some epidemiological studies have shown a weak statistical association between childhood leukaemia and higher than normal magnetic fields in the home. The international research effort continues.
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How are guidelines set?
The guidelines are based on the avoidance
of established health effects of electromagnetic fields. They are set
after extensive reviews of the scientific research on epidemiology,
biological effects, animal experiments and thresholds for human health
effects. The UK has adopted the guidelines published by the
International Commission on Non-Ionizing Radiation Protection
(ICNIRP).
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What research has been done on the possible risk of cancer from exposure to electromagnetic fields?
A great deal of research has been done world wide on examining possible health effects from EMFs, especially those associated with power lines. In March 2001, a report by an independent Advisory Group on Non-ionising Radiation (AGNIR) was published which reviewed all the information available from experimental studies on tissues, living cells and animals, and human volunteer and epidemiological studies.
ELF Electromagnetic Fields and the Risk of Cancer: Report of an Advisory Group on Non-Ionising Radiation, 6 March 2001.
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What were the main conclusions of Advisory Group on Non-ionising Radiation (AGNIR) in relation to Extremely Low Frequency (ELF) fields and cancer?
AGNIR concluded, 'Laboratory experiments have provided no good evidence that ELF electromagnetic fields are capable of producing cancer, nor do human epidemiological studies suggest that they cause cancer in general. There is however some epidemiological evidence that prolonged exposure to higher levels of power frequency magnetic fields, is associated with a small risk of leukaemia in children. In practice, the general public in the UK seldom encounters such levels of exposure. In the absence of clear evidence of a carcinogenic effect in adults, or of a plausible explanation from experiments on animals or isolated cells, the epidemiological evidence is currently not strong enough to justify the firm conclusion that such fields cause leukaemia in children. Unless, however, further research indicates that the finding is due to chance or some currently unrecognised artefact, the possibility remains that intense and prolonged exposures to magnetic fields can increase the risk of leukaemia in children.' (AGNIR Report, page 164, paragraph 15.)
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What is the international view of the possible health effects from electromagnetic fields (EMFs)?
In 2001 the International Agency for Research on Cancer (IARC) reported: "..... pooled analyses of data from a number of well-conducted studies show a fairly consistent statistical association between a doubling of risk of childhood leukaemia and power-frequency (50 or 60 Hz) residential ELF magnetic field strengths above 0.4 microTesla. In contrast, no consistent evidence was found that childhood exposures to ELF electric or magnetic fields are associated with brain tumours or any other kinds of solid tumours. No consistent evidence was found that residential or occupational exposures of adults to ELF magnetic fields increase risk for any kind of cancer.
Studies in experimental animals have not shown a consistent carcinogenic or co-carcinogenic effects of exposures to ELF magnetic fields, and no scientific explanation has been established for the observed association of increased childhood leukaemia risk with increasing residential ELF magnetic field exposure."
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Can I reduce my exposure to mobile phone emissions?
You can reduce your exposure by keeping your calls as short as possible or by text messaging. There are also three types of device that claim to reduce exposures. The first are covers that totally or partially enclose the handset. The second are clip-on or stick-on button type devices, which may contain fluids or crystals. Thirdly, there are hands-free kits. A report On the effectiveness of various types of mobile phone radiation shields prepared by SARTest Ltd for the Department of Trade and Industry is available.
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What is radioactive waste?
This is the residue of any process that uses radioactive material and
originates from a range of industries. These include the nuclear industry,
hospitals, universities, pharmaceutical companies and research
establishments. In general this waste consists of a mixture of radioactive
materials and can be solids, liquids or gases.
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Is all radioactive waste the same?
No. Radioactive waste is generally divided, for management purposes, into
four classes, which relate to the quantities of radioactivity involved and
the controls required:
- High level waste (HLW) – extremely high levels of radioactivity arising
from the reprocessing of nuclear fuel. Due to its radioactivity it produces
its own heat and must be cooled constantly. It is currently kept in
special, long-term storage.
- Intermediate level waste (ILW) – lower levels of radioactivity, which do
not require cooling. It is currently kept in special storage.
- Low level waste (LLW) – of such low activity levels that it may be disposed
of under controlled conditions or to specific authorised sites.
- Very low level waste (VLLW) – this waste is of sufficiently low activity
that it can be disposed of to landfill sites with domestic rubbish.
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What happens to radioactive waste?
Radioactive waste is either disposed of to the environment or treated and
stored. As with all industrial waste, the eventual fate of radioactive waste
is determined by its impact on people and the environment. Lower activity
wastes may be disposed of to the environment, higher activity waste is
currently placed in long term storage.
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How are radioactive discharges regulated or controlled?
Discharges to the environment are closely regulated and controlled by the
Government, through the Environment Agencies. These agencies use a system of
legal authorisations to set limits and controls on organisations that store
and discharge radioactive waste. There are continuous programmes of
inspection and monitoring of the environment around these sites, the results
of which are published by the Environment Agencies.
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How much radioactive waste is stored in the UK?
According to the Department of Environment Farming and Rural Affairs (DEFRA) in
April 2002 the radioactive wastes stored in the UK were:
- High Level Waste: volume 1960 cubic metres, mass 3290 tonnes, activity 57,800,000 terabecquerels*
- Intermediate Level Waste: volume 75,400 cubic metres, mass 90,400 tonnes, activity 5,290,000 terabecquerels*
- Low Level Waste: volume 14,700 cubic metres, mass 17,800 tonnes, activity 11 terabecquerels*
* 1 terabecquerel is 1,000,000,000,000 becquerels
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What are the government's policies for the management of the
radioactive waste that is stored?
The Government's policy on management of high and intermediate level waste
is under review. In 2001, it began a wide-ranging public consultation to
inform the development of its policy in this highly controversial area. The government set up the committee of radioactive waste management (CoRWM) http://www.corwm.org.uk/ to review, evaluate and consult on the various options for managing high and intermediate level radioactive waste. CoRWM have been tasked to produce recommendations in 2006.
The government is currently consulting on the policy for the long-term management of solid low level radioactive waste see http://www.defra.gov.uk/corporate/consult/radioactivity-llw/index.htm
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What are the options for the long-term management of intermediate level
and high level radioactive waste?
The options being considered CoRWM site
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What are the risks from long term storage of radioactive wastes?
Surface storage may leave a facility vulnerable to terrorist attack or
dispersion through accidents. However surface storage greatly eases the
long-term management of the material. Underground storage may be less
vulnerable to attack but carries a risk of contamination of ground water.
Both options present significant challenges eg, in designing structures that
will last many centuries.
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Does radioactive waste, discharged or stored, represent a significant
risk for the peoples of the UK?
For the vast majority the impact of radioactive waste is very small if not
insignificant. Even for people who live near major nuclear sites, the risk
is small compared to the other risks of modern living. In planning for long
term storage solutions, the Government has set stringent risk targets for
the public, which will be used in the selection and development of the
site(s).
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Are GPs qualified to carry out medical examinations under the Ionising Radiation Regulations and what are the criteria for qualification?
Only if appointed to do so by the Health and Safety Executive and after attending a one-day training course.
1) In the Ionising Radiation Regulations 1999 http://www.hmso.gov.uk/si/si1999/19993232.htm
"Appointed doctor" means, subject to regulation 39(5) (which relates to transitional provisions), a registered medical practitioner who is for the time being appointed in writing by the [Health and Safety] Executive for the purposes of these Regulations.
2) The Health and Safety Executive (Radiation Protection Adviser Issue 17 May 2000 at http://www.hse.gov.uk/hthdir/noframes/rad_prad/rpa17.htm#3 gives information on the Appointed Doctor system, including the introduction of a requirement for doctors appointed under IRR99 to attend a one day training course on the regulations, health effects of ionising radiation and the practical aspects of providing medical surveillance.
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How are radioactive sources controlled in the UK?
There are long standing legal controls on the use, storage and transport
of radioactive sources. It is the user's responsibility to comply
with this legislation. Compliance is monitored by the Environment
Agencies (England and Wales
and Scotland), the Health
and Safety Executive and the Department
for Transport. Part of the legislation is to ensure the security of
sources to prevent their loss, misuse or misappropriation.
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How easy is it to steal a radioactive source?
Several levels of security surround radioactive sources. Highly active
sources used in hospitals in radiotherapy are usually encased in substantial
shielding extremely difficult to remove and impossible to do so covertly.
Handling such sources would represent a significant risk to the potential
thief. Smaller sources of radioactive material are theoretically more vulnerable,
but covert misappropriation would still be extremely difficult. The potential
use as a health threat would be much smaller.
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How easy is it to disperse the contents of a sealed source into the
environment?
The design and manufacture of sealed sources is to exacting British
or international standards (BSI).
These specify rigorous tests for resistance to impact, fire and corrosion
to maintain integrity under normal and accident conditions. Determined
and very extreme actions would be therefore needed to breach source integrity.
In the unlikely situation that the capsule is breached it would be
possible for the source to contaminate the immediate environment. Widespread
contamination is more difficult, and dilution and dispersion may reduce
the risk to individuals.
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Who co-ordinates international safeguards for safety and security
of radioactive material?
The International Atomic Energy Agency
has sponsored many initiatives to improve the safety and security of radioactive
sources. Originally the initiatives were introduced because of a number
of incidents involving the mishandling of disused sources outside regulatory
and institutional control. Now the IAEA action plan includes measures to
reduce the risk of trafficking and malicious use of radioactive materials.
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What incidents have occurred with sources in the UK?
Details of incidents involving radioactive material are published by the
Health Protection Agency (HPA). There is
also the Ionising Radiations
Incident Databas (IRID), which analyses reported incidents in the workplace. Also there is a report on transport events pdf HPA site The site newsletters of
the major nuclear operators also contain information about incidents. Updated 6 December 2006
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What measures are in place to prevent the illicit import of radioactive
material into the UK?
Devices to detect radioactive material may be deployed at points of
entry into the UK where there are both permanent installations and mobile equipment
(Home Office).
In addition, various industries operate radiation detection equipment to
identify unauthorised movements of radioactive materials (e.g., the metal
recycling and nuclear industries).
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What happens when an object suspected to be a radioactive source
is found?
When the Police are informed of a suspect source, they initiate the
national arrangements for incidents involving radioactivity (The
National Arrangements for Incidents Involving Radioactivity (NAIR)).
Through NAIR, the Police have access to local radiological protection
expertise that can provide a rapid initial assessment. If necessary a secondary
response can be triggered to provide support with more specialist equipment.
14 January 2004
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What is polonium-210?
Polonium is a naturally occurring radioactive element. It is formed during the radioactive decay of uranium and thorium. It was first isolated in1898 thanks to the work of the distinguished Polish scientist Marie Curie, hence the name polonium. The isotope polonium-210 comes from uranium-238 via a long series of transformations that include radium-226 (radium was once used extensively in the luminising industry) and radon gas. Polonium-210 is also radioactive and decays by emitting alpha particles. The half life of the process (the time for the amount of radioactivity to decrease by half) is about 138 days during which the polonium decays to a non radioactive isotope of lead.
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How is polonium-210 made?
Polonium-210 could be extracted from uranium bearing rocks e.g. granite. It can however be made in larger quantities by bombarding the element bismuth with neutrons. The isotope bismuth-209 captures a neutron and becomes bismuth-210m. This unstable form undergoes radioactive beta decay with a half life of 5 days to become polonium-210. Some of the bismuth is also converted to thallium. Specialist research reactors, used to make radioactive isotopes for medical applications, also produce polonium-210. The amount of polonium likely to cause the symptoms seen in this incident can only have been produced in a large industrial scale facility.
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Is polonium-210 made in nuclear power stations?
No, UK nuclear power stations are not used for this sort of work. Nor is polonium-210 a significant component of nuclear waste.
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What are the uses of polonium-210?
Polonium-210 sources may be used as anti-static devices on spray guns or the polishing of plastics in industry. Anti-static guns and nozzles contain a small amount of polonium-210, encapsulated in a strip of copper and mounted in a stainless steel cartridge. The construction of these guns and nozzles is controlled to British Standard BS 5288:1976 (Sealed Radioactive Sources) and involves quite small amounts of polonium.
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Why is polonium-210 dangerous?
The alpha particles emitted by polonium-210 can be stopped by a sheet of paper or the dead layers of the skin. For the polonium to be harmful a person would have to eat it, drink it, breathe it in or absorb it through a cut. If eaten, dependent on the chemical form of the polonium, 10-50% could be taken up by the gut. This means that 50-90% would be excreted in the faeces within a few days. After uptake to blood, polonium-210 is widely distributed though soft body tissues including bone marrow and is eventually excreted, mostly in the urine with a half time (the time taken for the level of polonium-210 to fall by half) of about 50 days.
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Is any intake of polonium harmful?
Radiation doses, including those from polonium-210, are assumed to give rise to an increase in lifetime cancer risk. The larger the dose, the larger the risk. The very high radiation doses once polonium is inside the body can cause damage to tissues and organs and in the extreme can be fatal, as was seen in the victim of the recent incident.
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Why does the quantity matter?
The more polonium in the body, the more cells in the lining of the gut and the bone marrow will be killed by the radiation. At very high doses so many cells will die that the ones remaining will be unable to reproduce fast enough to replace the loss. There will be infection through the gut and severe blood cell deficiency. The body will not be able to withstand these changes and death results.
For smaller doses, fewer cells die and body’s natural defence mechanisms kick in.
Some cells hit by an alpha particle may not be destroyed but only damaged. When these cells go on to reproduce they may replicate the damaged form. These new cells may be cancerous. This is why there may be longer term health risks from much smaller uptakes of polonium.
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What about “innocent bystanders”
There have been reports of small amounts of polonium-210 contamination in areas used by the public. If anyone has been internally contaminated by inadvertently ingesting or inhaling polonium-210, it is most unlikely that they would receive a radiation dose high enough to give rise to any immediate medical symptoms. The long term risk would also be small.
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How can alpha radioactivity be detected?
Once inside the body, alpha radioactivity can only be detected by monitoring urine or faeces. External body surfaces, and areas such as walls, floors, carpets or airplane seats can be checked with portable (alpha) sensitive radiation monitors. The air in a room can be drawn through a filter paper and the paper monitored. Specialist laboratory tests are need to confirm that any radioactivity found is polonium-210.
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Where can I get updates on the public health issues arising from the death of Mr Alexander Litvinenko?
The Heath ProtectionAgency is publishing regular updates at http://www.hpa.org.uk/hpa/news/archive_06.htm
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What is COMARE?
COMARE is an independent expert advisory committee with members chosen for their medical and scientific expertise and recruited from Universities, Research and Medical Institutes. Members have never been drawn from the Nuclear or Electrical Power Supply Industries.
COMARE's terms of reference are "to assess and advise Government and the devolved authorities on the health effects of natural and man-made radiation and to assess the adequacy of the available data and the need for further research".
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COMARE 11 - Why was this report written?
This report considers the geographical distribution of childhood cancer throughout the UK and was produced in response to certain recommendations in their third report (1989). The study was carried out to ascertain whether patterns of cancer incidence around nuclear establishments were different from those in the rest of the UK.
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Has this epidemiological study the necessary power?
Yes, the study used as a database the National Registry of Childhood Tumours for the time period 1969-1993 which includes data on 12415 cases of leukaemia and non-Hodgkin’s lymphoma and 19908 solid tumour cases.
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What are the main conclusions?
Many cancers (including leukaemia) were shown to cluster in a non-random fashion in high socio-economic areas. The clustering was not more marked near nuclear power generating plants but there were excesses of some types of cancer near Sellafield, Dounreay, Aldermaston, Burghfield and Harwell. There was also a trend of risk with distance from Rosyth. The excesses, types of cancer and time scales were not consistent around these sites.
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Are the clusters of cancers linked with radioactive discharges?
Because there are not anomalous clusters of childhood cancers around all nuclear sites where there are discharges, the report concludes that the two are not specifically linked. However, the clusters in time and space around Sellafield (actually in the village of Seascale) and Dounreay are not likely to be due to non-random clustering. COMARE mentions population mixing as a possible explanation.
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Do COMARE suggest a causative link with any agent for childhood cancer?
The committee explores and explains the multistage theories of cancer induction and conclude that the present study’s results are consistent with an infective process i.e. one of the step’s in the development of cancer is a rare and unusual response to one or more (unidentified) infective agents.
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Overall will this report quell fears of whether childhood cancers are linked to radiation exposure from the environment?
The simple is answer is, no, although in general living near a power generating plant does not seem to confer excess risk. However, there are still largely unexplained and persistent excesses of cancers around certain sites which are historically those which have discharged the most radioactive materials.
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Other useful sources
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Disclaimer
The answers have been contributed by individual members of the Society, including members of the Communications Committee. Any views expressed and any information provided in the answers are not necessarily endorsed by the Society.
Updated 5 March 2007
