The U.S Environmental Protection Agency (EPA) defines a<unk>  as "any substance or mixture of substances intended for preventing, destroying, repelling, or lessening the damage of any pest".
A<unk>  may be a chemical substance, biological agent (such as a virus or bacteria), antimicrobial, disinfectant or device used against any pest. Pests include insects, plant pathogens, weeds, mollusks, birds, mammals, fish, nematodes (roundworms) and microbes that compete with humans for food, destroy property, spread or are a vector for disease or are a nuisance. Many<unk> s are poisonous to humans.
Pesticide
Food additive
Counterfeit drug
Designer drug
Inhalant
Alternative medicine
Prescription drug
Generic drug