Which label signal word indicates that a pesticide is the least hazardous to humans?

The signal word "Caution" indicates that a pesticide is the least hazardous to humans. This classification is part of a standardized system that helps communicate the level of toxicity and potential risk associated with a pesticide. "Caution" is used for products that pose relatively low risk if used according to label directions, meaning they are generally safer for human health, especially when compared to products labeled with "Warning" or "Danger."

In this context, "Warning" signifies a moderate level of toxicity, whereas "Danger" denotes a high toxicity level and indicates that the product could cause serious harm or even be fatal if mishandled. The term "Hazard," while it implies a risk, is not used as a specific signal word under the labeling system like the others and does not directly indicate the degree of risk as clearly as the other terms do. Thus, "Caution" effectively communicates that the pesticide presents the least hazard to humans in terms of potential exposure and health effects.