Metabolism (biotransformation) is the sum of the processes by which a foreign chemical is subjected to chemical change by living organisms.
LOEL is the lowest observable effects level.
NOEL is the no observable effects level.
Pharmacokinetics is the quantitation and determination of the time course and dose dependency of the absorption, distribution, biotransformation, and excretion of chemicals.
40 C.F.R. §799.9748