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

The signal word associated with very low oral LD50 values is "DANGER-POISON." This term indicates that the substance is highly toxic, with a low lethal dose, meaning that even a small amount can be hazardous or potentially lethal to humans or animals if ingested. The use of "DANGER-POISON" on pesticide labels serves to alert users to the high level of risk involved when handling or using the product, emphasizing the need for strict precautions and protective measures.

In contrast, the other signal words, "WARNING" and "CAUTION," suggest a lesser degree of toxicity compared to "DANGER-POISON." "WARNING" typically indicates moderate toxicity, while "CAUTION" suggests that a product is less harmful and has a higher LD50 value, meaning it requires less stringent safety measures. "DANGER" alone signifies a high level of toxicity, but without the "POISON" designation, it does not carry the same implication of very low oral LD50 values as "DANGER-POISON" does. Therefore, the combination of "DANGER" and "POISON" more precisely communicates the severe hazard posed by substances with very low oral LD50 values.