The term caution indicates that a substance is:

The term "caution" in relation to substances generally refers to those that are considered slightly toxic or relatively nontoxic. This classification indicates that while there may be some potential for harm, it is not severe, and proper handling can typically mitigate risks. Substances marked with this label often require basic safety measures but are not regarded as an imminent threat to health in standard usage scenarios.

In contrast, highly toxic substances demand immediate and rigorous protocols to safeguard against serious health hazards, whereas moderately toxic substances, while still posing significant risks, do not carry the same urgency as those classified as highly toxic. On the other hand, a classification of completely safe would imply no risk or caution is necessary, which does not align with the concept of "caution" that suggests a need for awareness and minimal protective actions when handling such substances.