Toxicity is defined as which of the following?

• A. An expression of the capacity of a substance to produce injury in a living host
• B. The rate at which a substance decomposes in the environment
• C. The color of a toxic chemical
• D. The environmental persistence of a chemical

Answer: (A)

Toxicity refers to the inherent ability of a substance to cause harm to a living organism. It describes how capable the chemical is of producing injury when a sufficient amount reaches the body through a given route. This concept matters because the actual harm depends on both the substance’s potency and the exposure (how much, how long, and by what route). The other statements describe environmental fate or appearance rather than the potential to cause injury: a rate of environmental decomposition, a color, or how long a chemical persists in the environment. In risk assessment, knowing a chemical’s toxicity helps compare potencies and, together with exposure, determines the likelihood of adverse health effects.