What is the meaning of "toxic" in a scientific context?

In a scientific context, "toxic" refers specifically to substances that can cause harm to living cells, tissues, or organisms. This can include a wide range of effects, from short-term irritations to long-term health issues, depending on the nature of the substance and the level of exposure. Toxic materials can disrupt biological processes, induce cell death, or lead to various diseases. Understanding toxicity is essential in fields such as medicine, environmental science, and nanotechnology, where the interaction of materials at the cellular level is a central concern.

The other interpretations from the options do not align with the established definition of toxicity. For instance, a beneficial material or a harmless substance cannot be considered toxic, as toxicity inherently implies the potential for damage or adverse effects on living organisms. Similarly, while infectious organisms can cause harm, they are not synonymous with the broader definition of toxic substances, which encompass a wider array of chemical compounds.