Radioactive Hazard SymbolRadiation Safety

Properties of Commonly Used Isotopes

Isotope H-3 C-14 P-32 S-35 Ca-45 Cr-51 I-125
Radiological Half Life 12.3y 5730y 14.3d 87.4d 163d 27.7d 60d
Biological Half Life 10d 0-25d 19d 90d variable 616d 138d
Max Beta Energy 19 keV 156 keV 1.71 MeV 167 keV 257 keV n/a n/a
Gamma Ray Exposure Rate 1cm from 1 mCi Point Source n/a n/a n/a n/a n/a .18 R/h 1.4 R/h
Dose Rate 1 cm from a beta point source 300 rad/h per mCi of activity 300 rad/h per mCi of activity 300 rad/h per mCi of activity 300 rad/h per mCi of activity 300 rad/h per mCi of activity n/a n/a
Range in Air 4.7mm 21.8cm 6.1m 24.4cm 47.9cm n/a n/a
Critical Organ whole body body fat bone whole body bone lower large intestine thyroid
Monitoring Method swipe counted by liquid scintillation swipe counted by liquid scintillation GM swipe counted by liquid scintillation GM NaI or other scintillation detector NaI or other scintillation detector
ALI, Oral Injestion, Occupational (uCi) 8E+4 2E+3 6E+2 1E+4 6E+3 (LLI wall) 2E+3 4E+4 4E+1 1E+2 (thyroid)
Release to Sewers, Monthly Average Concentration (uCI/ml) 1E-2 3E-4 9E-5 1E-3 2E-4 5E-3 2E-5
Special Considerations note 1, note 2, note 3 note 1, note 2, note 4, note 9 note 5 note 1, note 6, note 9 note 1 note 7 note 7, note 8

Notes

  1. millicurie amounts do not pose significant external exposure hazard
  2. many compounds can penetrate gloves and skin; consider wearing two layers of gloves and change top layer frequently
  3. additional notes on H-3: after use of >100 mCi open bench or >1000 mCi in a fume hood, bioassay by the Radiation Safety Section is required (prior to using H-3, you must have a baseline bioassay performed); place previously-opened containers of tritiated water into a fume hood, not a refrigerator; monitor storage areas where large activities of H-3 are kept as certain forms tend to "creep"
  4. because of the long halflife of C-14, take care not to contaminate items which are difficult to decontaminate
  5. notes on P-32: users handling > 5 mCi at a time require a TLD ring dosimeter; users handling > 10 mCi at a time require a whole body dosimeter; work behind shielding when possible; shield with plexiglass, NOT LEAD; wear eye protection
  6. some compounds, such as S-35 methionine, may vaporize on opening of container
  7. shield large (mCi) quantities with lead
  8. notes for I-125: users handling > 1 mCi carrier-free iodine on the open bench or > 10 mCi carrier-free iodine in a fume hood must report to the Radiation Safety Section for a thyroid bioassay within 24-48 hours of use (prior to work a baseline bioassay must be performed); reduce unbound fractions of carrier-free iodine as soon as possible with sodium metabisulfate or thiosulfate
  9. Surveys for gross levels of contamination may be performed using a Geiger counter. However, for a more sensitive analysis, particularily in radiologically uncontrolled areas, swipe surveys ans LSC analysis should be used.

ALI and sanitary sewer release values obtained from Code of Federal Regulations, Title 10, Part 20, Appendix B.

Questions?

Contact the Division of Research Safety, Radiation Safety Section (333-2755 or via e-mail) or visit our website: http://www.drs.illinois.edu/rss/.

Other Radiation Safety Fact Sheets are available from the Radiation Safety Section at our website: http://www.drs.illinois.edu/rss/factsheets/.

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