Iodine-131 Handling Precautions

SAFE
HANDLING
GUIDE
Iodine-131 Handling Precautions
I
8.04 d
ß–0.606
γ 0.364
0.637
E 0.971
131
This document contains general information designed to provide a basic understanding of radiation
safety. While we believe the information to be accurate, regulatory requirements may change and
information contained herein is not tailored to individual needs. A radiation protection specialist
should be consulted for specific applications.
Physical data
Dosimetry
Principal radiation emissions
Maximum beta energies: 0.248 MeV (2.1%)
0.334 MeV (7.4%)
0.606 MeV (89.3%)
Beta emission from 131I can present an external exposure
hazard to skin and eyes. Gamma emissions can present a
penetrating external exposure hazard. Individual iodine
metabolism can vary considerably(5). It may be assumed that
30% of an uptake of iodine is translocated to the thyroid
and 70% directly excreted in urine(5). Iodine in the thyroid is
retained with a biological half-life of 120 days in the form
of organic iodine. Organic iodine is assumed to be uniformly
distributed in all organs and tissues of the body except the
thyroid, and retained with a biological half-life of 12 days(5).
10% of organic iodine is directly excreted in feces and the
rest is returned to the transfer compartment as inorganic
iodine(5). The committed dose is significantly reduced due to
the short physical half-life of 131I(5).
(1)
Gammas: 0.723 MeV (1.8%)
0.637 MeV (7.3%)
0.364 MeV (81.2%)
0.284 MeV (6.1%)
0.080 MeV (2.6%)
X-ray: 0.030 MeV (3.9%)
Maximum range of beta in air: 165 cm (65 in)(2)
Unshielded exposure rate at 1 cm from a 1 mCi point
source: 2.16 R/h(3)
Unshielded exposure rate at 1 m from a 1 MBq point
source: 1.5 nC/kg/h
Half-value layer for lead shielding: 2.3 mm (0.091 in)(3)
Decay table
Physical half-life: 8.04 days(1).
Occupational limits(3)
To use the decay table, find the number of days in the top and
left hand columns of the chart, then find the corresponding
decay factor. To obtain a precalibration number, divide by
the decay factor. For a postcalibration number, multiply by
the decay factor. Visit www.perkinelmer.com/toolkit to
use our online Radioactive Decay Calculator.
Annual limit on intake: 30 µCi (1.1 MBq) for oral ingestion
and 50 µCi (1.8 MBq) for inhalation
Derived air concentration: 2 x 10-8 µCi/ml (740 Bq/m3)
Days
Days
0
10
20
30
0
1
2
3
4
5
6
7
8
9
1.000
0.422
0.178
0.075
0.917
0.387
0.164
0.069
0.842
0.355
0.150
0.063
0.772
0.326
0.138
0.058
0.708
0.299
0.126
0.053
0.650
0.274
0.116
0.049
0.596
0.252
0.106
0.045
0.547
0.231
0.098
0.041
0.502
0.212
0.090
0.038
0.460
0.194
0.082
0.035
PerkinElmer has developed the following suggestions for handling Iodine-131
after years of experience working with this beta, gamma and x-ray emitter.
General handling precautions for Iodine-131
1.­Designate area for handling 131I and clearly label all containers.
2. Store
131
I behind lead shielding.
3.­Wear extremity and whole body dosimeters while handling
mCi (37 MBq) quantities of 131I.
4.­­Use shielding to minimize exposure while handling
131
I.
5. Do not work over open containers.
6. Use tools to indirectly handle unshielded sources and
potentially contaminated vessels.
7. Prohibit eating, drinking, smoking and mouth pipetting in
room where 131I is handled.
8. Use transfer pipets, spill trays and absorbent coverings to
confine contamination.
9. Handle potentially volatile compounds in ventilated enclosures.
10. Handle millicurie (37 MBq) quantities in closed systems
vented through activated charcoal traps.
11.­­Sample exhausted effluent and room air by continuously
drawing a known volume through cartridges containing
activated charcoal.
18. ­Isolate waste in sealed, clearly labeled shielded containers
and hold for decay.
19. ­Establish surface contamination, air concentration, urinalysis
and thyroid burden action levels below regulatory limits.
Investigate and correct any conditions which may cause
these levels to be exceeded.
20. ­On completing an operation, secure all 131I; remove protective
clothing and dispose of protective coverings; monitor and
decontaminate self and surfaces; wash hands and monitor
them again.
Store Na131I solutions at room temperature because freezing
results in volatilization. Avoid acidic solutions to minimize
volatilization. Some radioiodine compounds may penetrate
gloves and skin. Therefore, these compounds should be handled
indirectly by using tools and wearing two pairs of gloves. The
outer layer of gloves should be changed frequently and whenever they are suspected to be contaminated.
References
12.­­Wear lab coat, wrist guards and disposable gloves for secondary protection.
1.­Kocher, David C., Radioactive Decay Data Tables, Springfield:
National Technical Information Service, 1981 DOE/TIC-11026.
13. Select gloves appropriate for chemicals handled.
2.­Calculated with computer code “Gamma” utilizing decay
scheme data from Kocher(1) and mass attenuation coefficient
for lead and mass energy absorption coefficients for air
from the Radiological Health Handbook, Washington:
Bureau of Radiological Health, 1970. The HVL reported
here is the initial HVL for narrow beam geometry.
14.­­Maintain contamination and exposure control by regularly
monitoring and promptly decontaminating gloves and surfaces.
15. Use pancake or end-window Geiger-Mueller detector,
NaI(Tl) detector or liquid scintillation counter to detect
16.­Submit urine samples for bioassay from 4 to 48 hours
after handling 131I to indicate uptake by personnel.
17. ­Monitor thyroid periodically with a NaI(Tl) detector to
determine thyroid dose.
131
I.
3.­U.S. Nuclear Regulatory Commission. 10 CFR 20 Appendix B –
Standards for Protection Against Radiation, 1994.
4.­ICRP Publication 30, Part 1, Limits for Intakes of
Radionuclides by Workers. Pergamon Press, Oxford, 1979.
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007035B_01
Jul. 2010