Which signal word is associated with very low oral LD50 values?

The signal word "Danger-Poison" is associated with very low oral LD50 values, indicating that the substance presents a high level of acute toxicity if ingested. The LD50 (lethal dose for 50% of the population) is a standard measure used to indicate the toxicity of a chemical; a lower LD50 value signifies that only a small amount of the substance can be lethal to a significant portion of test subjects.

In this context, the "Danger-Poison" signal word is used on pesticide labels to alert users about the extreme hazard posed by the product. The use of "Poison" specifically emphasizes that the material is so toxic that ingestion, even in small quantities, can result in severe health consequences or death. This positioning in the labeling system is critical for the safety of applicators, consumers, and the environment, ensuring that the appropriate precautions and handling procedures are followed when using such substances.

By contrast, the other signal words— "Caution," "Warning," and "Danger"—indicate lower levels of toxicity or lesser potential harm compared to "Danger-Poison," making them inappropriate for substances with very low oral LD50 values.