Which route of entry into the body is not usual in cases of mercury poisoning?

The route of entry into the body that is not typical in cases of mercury poisoning is inoculation. Inoculation generally refers to the introduction of a substance (such as a vaccine) into the body through a puncture in the skin or mucous membrane. This method is not a common means of exposure for mercury, which usually enters the body through other routes.

Mercury can be absorbed through the skin or mucous membranes when there is direct contact with mercury in elemental or other forms. Ingestion occurs when a person consumes contaminated food or water, which can lead to mercury poisoning, particularly in those who eat fish that have accumulated mercury. Inhalation can happen through the breathing of vapors from metallic mercury, especially in industrial settings, leading to respiratory absorption of the toxic metal.

While inoculation is a valid method of introducing substances into the body for medical treatments, it is not a typical exposure route for mercury, making it the least usual option in the context of mercury poisoning.