A portion or piece of a whole. A selected subset of a population or subset of
whatever is being studied. For example, in a study of people the sample is a
number of people chosen from a larger population [see population]. An
environmental sample (for example, a small amount of soil or water) might be
collected to measure contamination in the environment at a specific location.
ATSDR Glossary of Terms
Contaminant(s) - Population