Final answer:
The correct term for an agent used to reduce the number of bacteria on a toilet is a disinfectant. Disinfectants are applied to inanimate surfaces and compared to phenol for assessing their effectiveness; antiseptics are used on living tissues for infection control.
Step-by-step explanation:
An agent used to reduce the number of bacteria on a toilet would most accurately be called a disinfectant. Disinfectants are chemicals used for microbial control on inanimate surfaces. They serve to inactivate most microbes, but do not necessarily lead to sterilization as some resilient microbes, such as endospores, may survive the disinfecting process.
When discussing microbial control on living tissues, such as human skin, the correct term would be antiseptic. Antiseptics are applied to living tissues to prevent infection, and are crucial in healthcare settings to maintain cleanliness and prevent disease transmission.
The effectiveness of disinfectants has historically been evaluated against phenol, due to its prominent use by Joseph Lister in aseptic surgery. While chemical disinfectants such as chlorine bleach are commonly used on nonliving surfaces, they should be chosen with considerations for their intended use, safety, and ecological impact.