Safety Office
Reviewed: 06 April 2009
Radiation Risk Assessment - Indicative Source Information
The information in this table is provided to assist in assessing the risk from isotopes that have been used within the University. The
indicative dose rates can be used to estimate the cumulative exposure to external radiation from a procedure (see guidance on radiation
risk assessment).
Isotope
Principal
Principal
Emissions
energies
Half-life
Annual Limit
Indicative Dose Rate (uSv/hr/MBq)
Relative
on Intake -
Data assumes no shielding applied.
radio-
inhalation
5cm
10cm
30cm
50cm
1m
toxicity
Tritium (Water)
Beta
18.6 keV
12.33 y
1.1 GBq
Maximum range in air - 6mm; No skin dose at 1 cm
4
Tritium (Organic)
Beta
18.6 keV
12.33 y
480 MBq
Maximum range in air - 6mm; No skin dose at 1 cm
4
Carbon-14
Beta
156 keV
5734 y
34 MBq
Maximum range in air - 24cm; dose at 1cm 0.55 Sv/hr/MBq
Phosphorus-32
Beta
1.71 MeV
14.3 d
6.3 MBq
Phosphorus-33
Beta
249 keV
25.3 d
14 MBq
Maximum range in air - 50cm; dose at 1cm 0.55 Sv/hr/MBq
4
Sulphur-35
Beta
167 keV
87.4 d
15 MBq
Maximum range in air - 27cm; dose at 1cm 0.55 Sv/hr/MBq
4
Iodine-125
Gamma
35 keV
59.4 d
2.7 MBq
4.44
1.11
0.12
0.04
0.01
2
Iodine-129
Gamme
40 keV
1.57e7y
390kBq
0.37
0.09
0.01
0.004
0.001
2
Beta
150 kev
Gamma
365 keV
8d
1.8 MBq
138
34.44
3.83
1.38
0.34
2
Beta
606 keV
Sodium-22
Gamma
1.27 MeV
2.6 y
10 MBq
62
15.6
1.73
0.62
0.16
2
Sodium-24
Gamma
2.75 MBq
15 h
38 MBq
580
145
16.12
5.8
1.45
2
Beta
1.3 MeV
Calcium-45
Beta
256 keV
163 d
7.4 MBq
Maximum range in air - 52 cm; dose at 1cm 0.55 Sv/hr/MBq
Chromium-51
Gamma
320 keV
27.7 d
560 MBq
16.84
4.21
0.47
0.17
0.04
3
Iron-55
Gamma
126 keV
2.69 y
22 MBq
5.76
1.44
0.16
0.06
0.02
2
Iron-59
Gamma
1.1 MBq
45.1 d
5.7 MBq
222
55.5
6.17
2.22
0.56
2
Beta
467 keV
Zinc-65
Gamma
1.11 MeV
244.3 d
6.9 MBq
116
28.9
3.21
1.16
0.29
2
Copper-67
Gamma
185 keV
62 h
34 MBq
16.72
4.18
0.46
0.17
0.04
2
Iodine-131
1000
120
55
3
34
2
3
Beta
580 keV
Arsenic-73
Gamma
53 keV
80.3 d
Technetium-99m
Gamma
347 keV
6.01 h
Cadmium-109
Gamma
88 keV
453 d
Indium-111
Gamma
245 keV
Caesium-137
Gamma
662 keV
Beta
520 keV
Gamma
103 keV
Beta
705 keV
Gamma
279 KeV
Beta
210 keV
Samarium-153
Mercury-203
3.98
1.0
0.11
0.04
0.01
4
690 MBq
36.83
9.21
1.02
0.37
0.09
3
2.1 MBq
3.88
0.97
0.11
0.04
0.01
2
2.8 d
65 MBq
26.5
6.62
0.74
0.26
0.07
2
30.1 y
3 MBq
50.75
12.69
1.41
0.51
0.13
1
46.3 h
29 MBq
23.04
5.76
0.64
0.23
0.06
2
46.8 d
8.7 MBq
14.68
3.67
0.41
0.15
0.04
2
22 MBq
The above data are indicative. Dose rates are conservative in that no allowance is made for shielding.
Where there is a beta component as well as gamma the beta dose has not been included. For high-energy beta emitters this can be
significant close to the source. However a 1mm glass vial will reduce the beta dose rate from P-32 by 70%. The plastic of an eppendorf
tube will reduce the beta dose rate from P-32 by 30%.
Annual Limits on Intake are based on the quantity by inhalation that would result in a 20 mSv dose - i.e. the maximum annual dose
permitted under the Ionising Radiations Regulations. ALIs for ingestion are also available and may be higher or lower that the inhalation
route depending on the isotope.
Relative radiotoxicity ranks from 4 (lowest) to 1 (highest).
The sources of the data are The Radionuclide and Radiation Protection Handbook 2002 (Delacroix, Guerre, Leblanc and Hickman); HHSC
Handbook No 14 - Radiation Protection Handbook for Laboratory Workers (Connor and McLintock); and The Health Physicist's Companion
2003 (Syberad Ltd).