However, note that, in order to identify amounts of radioactive
substances which could be exempted from the need for regulatory control,
"exemption criteria" were established in the IAEA Safety Standards
(Safety Series No.115, International Basic Safety Standards for the
Protection against Ionizing Radiation and for the Safety of Radiation
Sources, Schedule I, p. 81-89; Vienna, 1996. IAEA is currently in
the process of updating IAEA Safety Series No.115). For practical
purposes, the IAEA defined values (e.g., "exemption levels") that
could be considered as "thresholds" below which the substances could
be automatically exempted from any control without further consideration.
National Regulatory Authorities normally establish exemption levels
for radioactive sources and other radioactive materials.