0.6 mCi (2 x 107 Bq) by inhalation, clearance in weeks.
0.4 mCi (1 x 107 Bq) by ingestion.
Half-value layer (the thickness required to attenuate the dose rate by 1/2) is 0.26
inches (6.5mm) of lead.
Multi-hundred mCi quantities need to be completely surrounded by beta
shielding material to prevent the betas from escaping and creating a source of
secondary annihilation radiation outside the shielding.
11. Special considerations:
Near an unshielded Na-22 source, dose rates due to beta radiation can be much
higher than dose rates due to gamma radiation.
Avoid direct eye exposure by interposing transparent shielding or indirect
Avoid skin dose by indirect handling.