WordNet sense 1 (having the qualities or effects of a poison):

toxicant

WordNet sense 2 (of or relating to or caused by a toxin or poison):

toxic

WordNet sense 3 (not suitable for food):

uneatable

WordNet sense 4 (marked by deep ill will; deliberately harmful):

venomous, vicious

WordNet sense 5 (having the nature of or resulting from malice):

malicious