If you tank mix a pesticide with a WARNING signal word with a pesticide that has a CAUTION signal word, you should treat the mixture as which signal word?

• A. DANGER
• B. CAUTION
• C. WARNING
• D. UNKNOWN

Answer: (C)

When you mix pesticides, you must follow the most restrictive signal word shown on any of the labels. Signal words reflect acute toxicity and guide how carefully you should handle and apply the product. If one component says WARNING and another says CAUTION, the mixture is treated as WARNING because WARNING represents a higher level of hazard than CAUTION. This ensures you use the higher level of protective equipment and follow the stricter handling precautions that come with WARNING. A DANGER label would apply only if any component carried DANGER, which isn’t the situation here. A CAUTION-only result would occur if all components were CAUTION, and UNKNOWN isn’t appropriate because there is a clear hierarchy among the signal words. So the mixture should be treated as WARNING.