LABELED COMPOUND	A compund consisting of labeled molecules. By observations of radioactivity or isotopic composition, this compund or its fragments may be followed through physical, chemical biological processes.
LATENT PERIOD	The period or state of seeing inactivity between the time of exposure of tissue to an injurious agent and response.
LD 50/30	The dose of radiation expected to cause death within 30 days to 50 percent of those exposed.
LICENSED MATERIAL	Source material, special nuclear material, or byproduct material received, possessed, used, transferred or disposed of under a general or specific license issued by the Nuclear Regulatory Commission.
LICENSEE	The holder of the license.
LIMITS	The permissible upper bounds of radiation exposures, contamination or releases.