What is the basis of the concept that all substances, in the right amounts, can become toxic?

The concept that all substances, in the right amounts, can become toxic is fundamentally rooted in the Dose Response concept. This principle posits that the effects of a substance depend on its concentration, or dose, in relation to the exposure and individual susceptibility. In other words, while certain substances may be harmless or beneficial at low doses, they can become harmful or toxic when taken in higher quantities.

This idea applies to a wide variety of substances, including everyday items like food, medications, and chemicals. The magnitude of the response—whether beneficial or harmful—depends on the amount of the substance that enters the body. Therefore, understanding the dose-response relationship is crucial for assessing the toxicity and safety of substances, allowing for informed decisions regarding exposure and use.

The other choices, while relevant to toxicity, do not encapsulate this central idea as comprehensively. The action-reaction principle pertains to physics and does not directly relate to toxicity. The concentration threshold focuses specifically on the level of a substance above which toxic effects start to occur, but it does not embody the broader understanding that any substance can be toxic depending on the dose. Exposure duration considers how long a substance is present in the body, which affects toxicity but is a factor of the dose-response relationship