In which scenario could a pollutant still be considered non-toxic?

A pollutant can still be considered non-toxic when it primarily affects aesthetic qualities only, rather than causing direct harm to health or the environment. For instance, a substance may alter the appearance of water or soil, leading to issues such as unpleasant odors or discoloration, but if it does not pose a risk to human health or ecological systems, it may be classified as non-toxic. This emphasizes the distinction between aesthetic impacts, which may be undesirable but not harmful, and those that result in serious health effects or ecological damage.

In contrast, pollutants that impact health directly are considered toxic due to their immediate risks to human well-being. Similarly, those that can be harmful in large quantities suggest a potential risk that escalates with increased exposure, disqualifying them from being classified as non-toxic. Lastly, pollutants that possess beneficial ecological traits could complicate their classification but do not align with the definition of non-toxicity, particularly if they still contribute to pollution. Thus, the recognition of a substance as non-toxic hinges significantly on its implications for health and the environment, which are well-captured by the scenario involving aesthetic qualities only.