Which of the following is NOT a route of entry for toxic materials?

Toxic materials can enter the body through various routes, but excretion is not one of them. Inhalation refers to the process where harmful substances are breathed in, allowing them to enter the bloodstream through the lungs. Ingestion involves swallowing toxic substances, which then enter the digestive system and can be absorbed into the body from there. Absorption occurs when toxic materials penetrate through the skin or mucous membranes, also leading to a potential buildup of harmful substances in the body.

Excretion, on the other hand, is the body's natural process of eliminating waste products and toxins after they have already entered the system. It does not refer to a way that toxic materials enter the body; instead, it is a route used by the body to remove them. Therefore, identifying excretion as not a route of entry for toxic materials highlights a fundamental aspect of toxicology and the mechanisms through which harmful substances can affect human health.