Iodine-125 (I-125) - doe-hdbk-1106-97

DOE-HDBK-1106-97

IODINE-125 (I-125)

Iodine-125 is a gamma and X-ray emitter. I-125 contamination may be detected by a thin-window

G-M probe or with liquid scintillation counting.

1. Maximum energy: 0.035 MeV gamma (6.5%), 0.027 MeV x-ray (112.5%) and 0.031

MeV X-ray (25.4%).

2. IAEA toxicity classification: Medium-high.

3. Physical half-life: 60 days.

4. Effective half-life (Teff): 42 days.

Critical organ: Thyroid gland.

Personnel monitoring: Internal uptakes evaluated by thyroid scan.

ALI:

0.06 mCi (2 x 106 Bq) by inhalation, daily clearance.

0.04 mCi (1 x 106 Bq) by ingestion.

8. Shielding: 0.25 mm of lead is the first half-value layer.

Other considerations for iodine compounds:

Volatilization of iodine (NaI) is the most significant hazard.

Simply opening a vial of sodium iodide at high-radioactive concentrations can

cause minute droplets to become airborne.

Solutions containing iodide ions should not be made acidic nor stored frozen;

both lead to formation of volatile elemental iodine.

Some iodide compounds can penetrate surgical rubber gloves - wear two pairs or

polyethylene gloves over rubber.

Can be easily absorbed through the skin.