What symbol is required on labels of highly toxic pesticides?

The symbol required on labels of highly toxic pesticides is a skull and crossbones. This symbol is universally recognized as a warning of danger and indicates that the substance is highly toxic to humans and can pose serious health risks if ingested, inhaled, or absorbed through the skin. The skull and crossbones serves as an immediate visual cue that reinforces the need for caution, thereby promoting safer handling and usage practices.

This label requirement is part of regulations that aim to mitigate the risks associated with the handling of hazardous chemicals, ensuring that individuals are adequately informed of the potential dangers before using such products. Other symbols, like the triangle, circle, or square, may have different meanings related to other classifications of pesticides or products but do not convey the same level of urgency regarding toxicity as the skull and crossbones symbol does.