How is toxicity defined in relation to substances?

Toxicity is specifically defined as the degree of biological harm that a substance can cause to living organisms. This definition encompasses a variety of factors, including the severity of the effects that exposure to the substance can produce. Toxicity is not solely about how quickly a substance is absorbed into the body, which informs the speed at which effects might be felt, but rather it is focused on the potential harm that those effects can inflict on health.

Understanding toxicity involves considerations such as the chemical structure of the substance, the dose, the route of exposure, and the specific biological systems affected. It's essential for determining safe handling practices and setting exposure limits for workers and consumers. This contrasts with considerations of effectiveness in pest control or the specific amounts necessary for a substance to achieve its intended effect, which relate more to practicality in application than to the fundamental risks posed by toxicity.