__________________ is the capacity of a substance to produce an unwanted effect when that substance has reached a sufficient concentration at a certain site in the body.

Toxicity refers to the inherent capacity of a substance to cause harm or an unwanted effect to living organisms when it reaches a certain concentration at a specific site in the body. This capacity can depend on various factors, including the nature of the substance, the duration of exposure, and the individual’s health and sensitivity.

In this context, toxicity emphasizes the relationship between the chemical or physical characteristics of the substance and the potential adverse health outcomes that can result from its presence in the body. This understanding is vital in safety practices, as it helps identify and manage risks associated with exposure to hazardous substances in a workplace or environmental setting.

The other concepts, though related, do not specifically define the capacity of a substance to produce adverse effects. For instance, hazard is often associated with the potential for an item to cause harm but does not inherently imply the effect will occur at all concentrations. Reactivity refers to how a substance behaves in chemical reactions, which is distinct from its potential for causing harm. Exposure relates to the situation of being in contact with or subjected to a substance, without necessarily indicating the harmful effects that might follow.