|toxic: a toxic substance, usually used in the plural:
toxics flowed from the factory.
toxin: a poisonous substance that is a specific product of the metabolic activities of a living organism.
toxicant: a toxic agent, usually one produced by human-made activity, such as pesticide.
Although strictly speaking toxin should be used only for biologically produced substances and not as a synonym for toxic or toxicant, popular usage interchanges the terms. A toxic agent is anything that can produce an adverse biological effect.