Safe Working With Ionising Radiation

1. Safe Working With Ionising Radiation

3. Objectives Foundation for Training in School Understand principles radiation types and effects biological effects relative risk legislation university arrangements Safe Practice

4. Atomic Structure

5. Isotopes

6. Ionisation

7. Half - life

8. Types of Radiation Video

9. Types of Radiation Alpha From heavy nuclei (e.g. Americium 241) Helium nuclei (2P+2N) 1500 ionisations Dangerous internally Easily shielded as very large particles Sheet of paper or plastic film Small distance of air Dead outer layer of skin

10. Types of Radiation Beta Particles (B) High speed electrons from nucleus Identical to orbital electrons Neutron Proton + B- Energy dependent penetrating power 3H - 18.6 KeV 14C - 156 KeV 32P - 1.71 MeV Rule of thumb for maximum range of beta particles 4 metres in air per MeV of charge P32 can travel up to 7 m in air but 3H only 6mm! Easily shielded with perspex, higher energy needs greater thickness 10 mm will absorb all P32 betas Cannot reach internal organs

11. Types of Radiation Bremsstrahlung X-radiation resulting from high energy � particle absorption in high density shielding, e.g. lead. Risk with 32P and similar high energy � emitters. Shield � with lightweight materials such as perspex. Very large activities can still produce some Bremsstrahlung from perspex - supplement perspex with lead on outside to absorb the X-rays.

12. Types of Radiation Gamma Radiation (Y) Electromagnetic radiation Emitted from nucleus Readjustment of energy in nucleus following a or � emission Variable energy characteristic of isotope Highly penetrating 5 - 25 cm lead 3m concrete Can reach internal organs Can pass through the body

13. Types of Radiation X-Radiation Similar to gamma but usually less energetic Originates from electron cloud of the nucleus Produced by machines - can be switched off! Also produced by some isotopes Iodine-125 produces both gamma and x-rays Broad spectrum of energy

14. Types of Radiation Neutrons Large, uncharged, physical interaction. Spontaneous fission (Californium 252) Alpha interaction with Beryllium (Am-241/Be) Shield with proton-rich materials such as hydrocarbon wax and polypropylene. Americium/Beryllium sources are used in neutron probes for moisture or density measurement in soils and road surfaces etc. These also emit gamma radiation.

15. Units of Radiation SI units Becquerel, Gray, Seivert replaced Curies, Rems, Rads Activity Dose absorbed equivalent committed

16. Units of Radiation - activity Quantity of r/a material Bequerel (Bq; kBq; MBq) 1 nuclear transformation/second 3.7 x 1010 Bq = 1 Curie Record keeping Stock, disposals Expt protocols

17. Units of Radiation - dose Absorbed - Gray (Gy) Radiation energy deposited 1 Gy = 1 joule/kg Dose Equivalent - Seivert (Sv) modified for relative biological effectiveness beta, gamma, X = 1 alpha, neutrons = 10-20

18. Units of Radiation - relationship quantity x energy = dose rate (uSv. hr-1) number of DPS (Bq) energy in electron volts 1 eV = 1.6 x 10-13 joules e.g. 1 MBq of a 1MeV source, thus 1 MeV = 1.6 x 10-7 joules, and 1 MBq = 106 disintegrations per second, hence Energy flux = 1.6 x 10-1 joules/second = 576 joules/hour [Note: 1 Sv/h = 1 joule/kg/h deposited in tissue]

19. Units of Radiation - committed Internal irradiation until decay or elimination radiological and biological half-lives data for 50-year effect Annual Limit on Intake (ALI) limit on committed dose equivalent quantity causing dose limit exposure

20. Exposure to Ionising Radiation Environment Naturally occurring radioactive minerals remaining from the very early formation of the planet. Outer space and passes through the atmosphere of the planet � so-called cosmic radiation. Man-made medical treatment and diagnosis. industry, primarily for measurement purposes and for producing electricity. fallout from previous nuclear weapon explosions and other accidents/incidents world-wide. Ionising Radiation and How We Are Exposed to It Ionising radiation is the energy produced from natural and man-made radioactive materials. It is present in the environment because of naturally occurring radioactive minerals remaining from the very early formation of the planet. This leads to exposure to gamma rays and radioactive radon gas from certain rocks and from radioactive material in our food and drink. We are also exposed to natural ionising radiation that comes from outer space and passes through the atmosphere of the planet � so-called cosmic radiation. There are three main sources of man-made ionising radiation. First, it is used in medicine for treating cancer and for the diagnosis of many diseases. Second, radioactive materials are also used in industry, primarily for measurement purposes and for producing electricity. Both medical and industrial uses of radiation produce radioactive waste. Third, it is present as fallout from previous nuclear weapon explosions and other accidents/incidents world-wide. Exposure of the UK population to man-made ionising radiation from medical and industrial activity is closely controlled and the estimation of all exposures, whether from natural or man-made radioactive sources, is undertaken by NRPB. These estimates show that, on average, doses from industrial activity plus weapons fallout are a very small part of the total (less than 1%), doses from medical practices are greater (about 14%) and the remainder (about 85%) comes from natural sources. Similar figures are seen in other developed countries. The damaging effects of ionising radiation come from the packages of high energy that are released from radioactive material. Although different types of ionising radiation have different patterns of energy release and penetrating power there is no general property that makes man-made ionising radiation different and more damaging than the ionising radiation that comes from natural radioactive material. This means that we can make direct comparisons between doses from man-made sources of ionising radiation and those from natural sources. Finally it is important to know that the radiations in the environment that come from sunlight, power-lines, electrical equipment and mobile phone systems do not have enough energy to produce these ionisations. Therefore, they are called non-ionising radiations.Ionising Radiation and How We Are Exposed to It

21. Biological Effects of Radiation Exposure Ionising radiation affects the cells of the body through damage to DNA by: Direct interaction with DNA, or Through ionisation of water molecules etc producing free radicals which then damage the DNA. Some damaged cells might be killed outright so do not pass on any defect. In some cases cell repair mechanisms can correct damage depending on dose. Ionising Radiation Damage and Cancer There is very strong scientific evidence that the energy from radioactive material affects the cells of the body, mainly because of the damage it can cause to cellular genetic material known as DNA. DNA controls the way in which each individual cell behaves. At high doses enough cells may be killed by damage to DNA and other parts of the cell to cause great injury to the body and even rapid death. At lower doses there will be no obvious injury but a number of the cells that survive will have incorrectly repaired the DNA damage so that they carry mutations. Some specific mutations leave the cell at greater risk of being triggered to become cancerous in the future. The body will already carry cells with these mutations from other causes but the ionising radiation exposure increases the number of these mutant cells. It therefore increases the chance of cancer development, usually after many years. The scientific information that has been obtained worldwide leads NRPB to believe that even the lowest dose of ionising radiation, whether natural or man-made, has a chance of causing cancer. The extra cancer risk from very low doses will be extremely small and, in practice, undetectable in the population. However the extra cancer risk at higher doses may be detectable using statistical methods. Even after high dose exposure it is rarely possible to be certain that radiation was directly responsible for a cancer arising in an individual.Ionising Radiation Damage and Cancer

22. Deterministic Effects. Threshold beneath which there is no effect and above which severity increases with exposure. High dose effects - cells may be killed by damage to DNA and cell structures. Clinically observable effects include: 5 Sv to whole body in a short time is fatal. 60 Sv to skin causes irreversible burning. 5 Sv to scalp causes hair loss 4 Sv to skin causes brief reddening after three weeks 3 Sv is threshold for skin effects. Biological Effects of Radiation Exposure

23. Stochastic (Chance) Effects No threshold dose, probability of effect increases with dose but severity of effect remains unchanged Lower dose effects No obvious injury, Some cells have incorrectly repaired the DNA damage and carry mutations leading to increased risk of cancer. Rapidly dividing cells most at risk � blood forming cells in bone marrow; gut lining. Biological Effects of Radiation Exposure

24. Cancer Risk at Low Doses Evaluation of Cancer Risk Studied for decades. atomic bomb explosions in Japan, fallout from nuclear weapons tests radiation accidents. medical irradiations, work (e.g. nuclear power industry) living in a region that has unusually high levels of radioactive radon gas or gamma radiation. The Estimation of Cancer Risk at Low Doses The cancer-causing effects of ionising radiation at high doses have been known for many decades. Since then, there have been many large studies worldwide of cancer arising in people exposed to high and low doses. These studies include people exposed to the atomic bomb explosions in Japan, to fallout from nuclear weapons tests and during radiation accidents. Information is also available from people irradiated for medical reasons, during their work or as a result of living in a region that has unusually high levels of radioactive radon gas or gamma radiation. From all of this scientific work published in peer-reviewed papers we know more about cancer risk after ionising radiation than for any other cancer-causing substance. However, because cancer is unfortunately a common disease with many causes it is extremely difficult to measure directly the small extra risk from ionising radiation when the doses are very low. National and international organisations worldwide constantly discuss the best way to use the cancer information that we have to make estimates of the risks at the low doses that are received by the general public and workers. Special attention is given to the risks from man-made ionising radiation that can be controlled and regulated. As mentioned earlier, it is also important to take account of the risks from natural radiation, most of which cannot be controlled. At present the estimate of cancer risk at low doses recommended by NRPB for use in the UK predicts that a lifetime of exposure of the population to all sources of ionising radiation (natural plus man-made) could be responsible for an additional risk of fatal cancer of about 1% � this can be compared with a life-time risk of cancer of about 20�25% from all causes. The very small doses from non-medical, man-made radiation would be responsible for only a tiny fraction (about one-hundreth) of this 1% radiation risk. Therefore, compared with other known cancer risk factors in the population such as cigarette smoking, excessive exposure to sunlight and poor diet, the risk to the population from non-medical man-made radiation is generally agreed to be very small indeed. It is the responsibility of NRPB to advise the UK Government on cancer risk estimates and standards for radiation protection. At present there are only small differences in the risk estimates used by different countries world-wide for the protection of their populations � almost all countries follow the recommendations made by the independent International Commission on Radiological Protection (ICRP). However, from time to time scientific advances make it necessary to consider an adjustment of these estimates and this can be done at a national as well as international level. To illustrate this, a review by NRPB in 1987 of newly published epidemiological studies led to a recommendation to increase the estimate of low dose cancer risk to be used in the UK. This was accepted by Government and within a few years other national and international bodies came to similar conclusions. NRPB, through its Advisory Group on Ionising Radiation (AGIR), continues to assess radiation cancer risks to the UK population. Most recently leukaemia risks have been reviewed (Docs NRPB 14(1) 2003), a sub-group of AGIR has been formed to examine solid cancer risks.The Estimation of Cancer Risk at Low Doses

25. Life-time risk of cancer from all causes of about 20�25%. Exposure to all sources of ionising radiation (natural plus man-made) could be responsible for an additional risk of fatal cancer of about 1% Dose from natural background radiation is about 2.2 mSv per year. Dose from non-medical, man-made radiation 0.02 to 0.03 mSv per year (1/100th natural background), 0.01% of additional cancer risk. More significant cancer risk factors include: cigarette smoking, excessive exposure to sunlight, and poor diet. Cancer Risk at Low Doses

26. Cancer Risk at Low Doses Most simplistic assumption is linear relationship between dose and risk This produced the following risk probabilities: Fatal Cancer 1 in 25,000 per mSv Non-fatal cancer 1 in 125,000 per mSv Hereditary Effect 1 in 125,000 per mSv Combined risk 1 in 18,000 per mSv

27. Biological Effects 4-10 Sv - death 1 Sv - clinical effects 100 mSv - clinical effects on foetus 50 mSv - max lifetime univ. dose 20 mSv - annual whole body dose limit 6 mSv - classified worker 2.5 mSv - average annual exposure (UK) 1 mSv - foetus after pregnancy confirmed 150 - 250 uSv - max annual dose at univ. 20 uSv � average annual dose at univ.

28. Perspective on Exposures Nature of work AND precautions in place show risk from exposure at work is extremely low. 10-15% of those subject to dosimetry receive a measurable dose, Average dose ~ 18uSv 0.1% of the dose limit of 20 mSv, 1% of that received from natural background radiation (2.2 mSv). Follow Safe Procedures

29. Properties of Main Isotopes

30. Legislation Health and Safety Ionising Radiations Regulations 1999 Environmental Radioactive Substances Act 1993

31. Ionising Radiations Regulations 1999 Worker protection dose limits justification risk assessment for exposure restrict exposure through equipment, procedure, expt design time, distance , shielding

32. Protection through distance Inverse square law applies Distance Dose rate (uSv/hr) 1m 1 2m 0.25 4m 0.06

33. Protection through distance HOWEVER !!!!!! Distance Dose rate (uSv/hr) 100cm 1 50cm 4 30cm 9 10cm 100 1cm 10,000 1mm 1,000,000

34. Ionising Radiations Regulations 1999 Local Rules RPS�s for all areas Worker/Project registration Designation of areas; access control Secure storage and accounting Movement packaging and labelling No posting or carriage on public transport

35. Radioactive Substances Act 1993 Enforced by Environment Agency. Licensing regime stocks accumulation and disposal of waste specific limits on isotope and quantity, disposal route and disposal period Strict record keeping essential

36. Administrative Controls Project Registration Isotopes Quantities Disposal routes Lab Facilities Worker Registration Project Dosemeter - Care Amend Details if Work Changes

37. End of Part One X-ray and Sealed Source Users to Other Room Harry Zuranski Sign in.

38. Isostock - Computer Recordshttp://www.nottingham.ac.uk/safety/publications/radiation.html

39. cpres/v1b/ca/1998-08/ 39 The Use of Radiochemicals in Life Science Research

40. 40 Definitions Radioactivity - the property of certain nuclides of emitting radiation by the spontaneous transformation of their nuclei Specific activity - Activity per unit mass of a compound Radioactive concentration - The activity per unit quantity of any material in which a radionuclide occurs Radiochemical purity - the amount of radioactivity in the stated chemical form ( does not take into account non-radioactive impurities)

41. Production of radiochemicalsneutron in / proton out

42. Isotope production Isotope 3 Hydrogen (Tritium) 14 Carbon 35 Sulphur 32 Phosphorus 33 Phosphorus 125 Iodine Stable daughter nuclide Helium -3 Nitrogen -14 Chlorine - 35 Sulphur -32 Sulphur - 33 Tellurium - 125

43. 43 Commonly used isotopes

44. cpres/v1b/ca/1998-08/ 44 14C maximum specific activity

45. cpres/v1b/ca/1998-08/ 45

46. 46 Carbon-14 Low energy b emission - no shielding required Long half-life -less time pressure Low specific activity - low sensitivity Detection scintillation counter autoradiography Geiger counter phosphorimager Labelled compounds generally stable - few decomposition problems Label is part of the backbone of molecule Labelled molecules are natural species - no artefacts

47. cpres/v1b/ca/1998-08/ 47 14C is in the backbone

48. cpres/v1b/ca/1998-08/ 48

49. 49 H-3 (Tritium) Very low energy b emission - no shielding required Long half - life High specific activity - reasonably sensitive, but weak emission Detected by scintillation counter detection less easy autoradiography less accurate and fluorography less efficient than 14C phosphorimager Labelled compounds less stable - radiation decomposition problems Label on periphery of molecule - no confidence in label position Labelled molecules are natural species - no artefacts

50. cpres/v1b/ca/1998-08/ 50 Label moves around the molecule

51. cpres/v1b/ca/1998-08/ 51

52. 52 Iodine -125 g emission - lead shielding required Short half-life - time pressures Very high specific activities - high sensitivities Detection Gamma counter Scintillation probe Autoradiography phosphorimager Labelled compounds stable - some decomposition problems Label covalently bound to molecules - position of label fixed Not often part of natural molecule - artefacts

53. 53 Phosphorus - 32 High energy b emission - shielding required (perspex and lead) 1 MBq in 1ml plastic vial @ 1m 2.5uSv/hr @ 10cm 200uSv/hr 30MBq in 1ml plastic vial @ 10cm 6mSv/hr 25 hours of work = 150mSv, i.e.Classified Worker NEVER HOLD VIAL IN FINGERS

54. Phosphorus - 32 High energy b emission - shielding required (perspex and lead) Short half-life - time pressures Very high specific activity - very high sensitivity Detection Scintillation counter Cerenkov counter Geiger counter Autoradiography phosphorimager Labelled compounds unstable - decomposition problems Label covalently bound to molecule - position fixed Labelled molecules natural species - no artefacts

55. 55 Phosphorus - 33 Low energy b emission - low shielding required (1cm perspex) Short half -life - time pressures High specific activity - high sensitivity Detection Scintillation counter Easy to detect Proportional counter and accurate counting Geiger counter Autoradiography phosphorimager Labelled compounds generally stable - few decomposition problems Label covalently bound to molecule - position of label fixed Labelled molecules are natural species - no artefacts

56. 56 Sulphur -35 Low energy b emission - low shielding required (1cm perspex) Shortish half-life - some time pressures High specific activity - high sensitivity Detection Scintillation counter Proportional counter Geiger counter Autoradiography phosphorimager Labelled compounds generally stable - few decomposition problems Label covalently bound to molecule - position of label fixed Labelled molecules may be natural (S-35 Met) or not (S-35 nucs)

57. 57

58. 58 Resolution

59. 59 Comparison P-32/P-33/S-35 Resolution in autoradiography S-35 > P-33 > P-32 Sensitivity in detection P-32 > P-33 > S-35 Probe stability S-35 > P-33 > P-32 Decay rate P-32 > P-33 > S-35

60. 60 Choosing an isotope Detection method Resolution required Sensitivity Specific activity Formulation - aqueous/ethanol Position of label - important in metabolic studies / can affect protein binding

61. 61 Working safely with radioactivity Understand the nature of the hazard and get practical training Plan ahead to minimise handling time Distance yourself appropriately from sources of radiation Use appropriate shielding Contain radioactive materials in a defined work area Wear appropriate protective clothing and dosimeters Monitor the work area frequently Follow the local rules and safe ways of working Minimise accumulation of waste and dispose of it correctly After completion of work monitor yourself and work area

62. cpres/v1b/ca/1998-08/ 62 Radiation Decomposition The chemical decomposition of a compound caused by, or accelerated by, the presence of one or more radioactive atoms in the molecule

63. 63 Modes of decomposition

64. 64 Typical rates of decomposition Carbon -14 1-3% per year Tritium 1-3% per month Sulphur -35 1-3% per month Phosphorus -32 1-3% per week Iodine -125 5-10% per month

65. cpres/v1b/ca/1998-08/ 65 Stability of [2,4,6,7-�H]Oestradiol

66. cpres/v1b/ca/1998-08/ 66 Effect of Specific Activity

67. cpres/v1b/ca/1998-08/ 67 Effect of temperature

68. cpres/v1b/ca/1998-08/ 68 Effect of temperature

69. cpres/v1b/ca/1998-08/ 69 Effect of temperature

70. 70 Effect of slow freezing

71. cpres/v1b/ca/1998-08/ 71 Effect of free radical scavengers

72. cpres/v1b/ca/1998-08/ 72 Effect of free radical scavengers

73. 73 Control of decomposition Store at lowest specific activity Store at lowest radioactive concentration Disperse solids - store under inert atmosphere Add 2% ethanol to aqueous solutions Store in the dark Use RedivueTM formulations Tritium - Store just above freezing point or -140 Reanalyse immediately prior to use Aliquot if long storage expected

74. cpres/v1b/ca/1998-08/ 74