What is the definition of toxicity?

The definition of toxicity refers specifically to the capacity of a chemical to cause injury or death to living organisms. This encompasses how harmful or poisonous a substance can be, depending on various factors like dose, duration of exposure, and the organism's susceptibility. Understanding toxicity is crucial in fields such as pest control, environmental science, and health care, as it helps professionals assess the risks associated with chemicals and their impact on organisms within an ecosystem.

The other options do not accurately define toxicity. For instance, a substance enhancing growth relates to its beneficial effects rather than its harmful impacts. Determining a chemical's usefulness is a broader evaluation that considers efficacy and practicality, not specifically its potential to cause harm. Similarly, measuring drug effectiveness in plants focuses on the beneficial effects of a substance rather than its adverse effects. Thus, the importance of identifying the proper definition lies in ensuring safety and gauging risks associated with chemical use.