Answer:

tox

Answer	Crossword Clue
TOX	... screen (lab test)
TOX	Crime lab sci.
TOX	Poison sci.

TOX	.. screen: health care test for poisons, drugs, etc.
TOX	.. screen: medical test
TOX	Poison: Prefix.
TOX	Poisonous: Prefix
TOX	Medical examiner's subj.
TOX	Study of poisons: Abbr.
TOX	Food safety subj.
TOX	... screen (drug test)