The Collaborative International Dictionary of English v.0.48:

Toxicology \Tox`i*col"o*gy\, n. [Gr. toxiko`n poison + -logy;
   cf. F. toxicologie. See Toxic. ]
   The science which treats of poisons, their effects,
   antidotes, and recognition; also, a discourse or treatise on
   the science.
   [1913 Webster]

WordNet (r) 3.0 (2006):

toxicology
    n 1: the branch of pharmacology that deals with the nature and
         effects and treatments of poisons

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "toxicology":
   acaricide, anthelmintic, antibiotic, antiseptic, bug bomb,
   carbamate insecticide, chemosterilant,
   chlorinated hydrocarbon insecticide, contact poison, defoliant,
   disinfectant, eradicant, fumigant, fungicide, germicide, herbicide,
   insect powder, insecticide, microbicide, miticide,
   organic chlorine, organic phosphate insecticide, pesticide, poison,
   rat poison, roach paste, roach powder, rodenticide, stomach poison,
   systemic, systemic insecticide, toxic, toxicant, toxin, venin,
   venom, vermicide, virus, weed killer