53 Radioactive Materials Safety Manual 59Fe IRON-59 Half - Life Physical Biological Effective 44.6 days 800 days 44.2 days Radiation Emitted Type Energy (max) Beta 273 keV (45.2%) 466 keV (53.1%) Gamma 1.099 MeV (56.5%) 1.292 MeV (43.2%) External Hazard 1 meter 1 cm Dose rate from a 1 mCi (37 MBq) point source: 0.66 mrad/hr (6.6 mGy/hr) 6.6 rad/hr (66 mGy/hr) Internal Hazard Effective Committed Dose Ingestion Inhalation Equivalent per Unit Intake: 6.7 mrem/µCi (1.81 x 10-9 Sv/Bq) 14.8 mrem/µCi (4.0 x 10-9 Sv/Bq) Annual Limit on Intake: (ALI)* 800 µCi 300 µCi *ALIs expressed are from Appendix B, Table 1 – Iowa Administrative Code 641.40 (136C). Special Considerations • 59Fe emits relatively energetic gamma rays which can pose a significant external hazard. • High external doses to the fingers can result from direct handling of unshielded vials of millicurie quantity 59Fe solutions. • Because of its relatively long effective half-life, 59Fe has a low annual limit on intake. Radiation Safety Practices • Dosimetry – Whole body badge required when working with quantities of 100 µCi (3.7 MBq) or more; ring badge required when working with quantities of 1 mCi (37 MBq) or more. • Bioassay – Required for individuals involved in spills or other incidents where significant uptake is suspected. • Shielding – 4.5 cm lead provides 95% attenuation; lead HVL is 1.1 cm. • Surveys – GM meter surveys, wipes analyzed in an LSC or gamma counter. • General – Bare source vials of 59Fe should be handled with leaded rubber gloves; shielded containers, tongs, or vial/tube racks.
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