This document interprets signal words seen on pesticide labels and discusses the toxicity criteria used in determining the appropriate signal word for the pesticide. Examples of typical statements found on pesticide labels which convey information to the handler of the product are provided.
When reviewing a pesticide label prior to handling the product, one may see a prominent display of one word on the front panel of the label. What does it mean to see one of the following signal words: "CAUTION," "WARNING," or "DANGER?" What does it mean if the product's label has no signal word displayed? The signal word conveys a message to the product's handler regarding its acute toxicity.
The signal word for a pesticide is typically determined by the results of the six acute toxicity studies performed with the product formulation. The acute oral, dermal, and inhalation studies evaluate systemic toxicity by those routes of entry. The primary eye and skin irritation studies measure irritation or corrosion, while the dermal sensitization study evaluates the potential for allergic contact dermatitis. With the exception of dermal sensitization, each acute study is assigned to a toxicity category based on the study results (Table 1).
Determining the Precautionary Labeling Signal Word
When required. A signal word is required for all registered pesticide products unless the pesticide product meets the criteria of toxicity category IV by all routes of exposure. If a pesticide manufacturer desires its label to list a signal word in this case, it must be "CAUTION."
Determining the signal word. The signal word is determined by the most severe toxicity category assigned to the five acute toxicity studies seen in Table 1 or by the presence of methanol in concentrations of 4% or more. Table 2 lists the appropriate signal word based upon toxicity category. Examples of appropriate signal words based upon toxicity studies are provided in Table 3. Typical statements seen on pesticide labels for acute oral, dermal, and inhalation toxicity are shown in Tables 4, 5, and 6, respectively. Typical statements seen on pesticide labels for products which potentially cause primary eye irritation are shown in Table 7, and statements for products which potentially cause primary skin irritation are shown in Table 8. Table 9 lists typical statements for dermal sensitization.
Location and prominence. The signal word is required to appear on the front panel of the label, and the EPA requests pesticide manufacturers to place it on a separate line from the required Child Hazard Warning statement (Keep Out of Reach of Children). The signal word is also required on any supplemental label intended to accompany the product in distribution or sale.
Related information. Because of the potential for confusion, the EPA historically has not approved labels containing the terms, "caution," "warning," or "danger," except as the signal word for that label. For example: "CAUTION: Wash hands before eating, or smoking" on a label with the signal of "CAUTION."
POISON—Skull and Crossbones Symbol
When required. The word "POISON" and the skull and crossbones symbol are required for products classified as toxicity category I for acute oral, acute dermal, or acute inhalation toxicity studies. If the inert ingredient, methanol, is present at 4% or more in the product, the EPA suggests that the manufacturer post the skull and crossbones symbol on the label. Examples are shown in Table 3.
Location and prominence. If required, the word "POISON" and the skull and crossbones symbol must appear in immediate proximity to each other. The word "POISON" must appear in red on a background of a distinctly contrasting color. In addition, the EPA requests that the "POISON" and the skull and crossbones symbol appear near the signal word "DANGER" (Figure 1).
Fishel, F.M. 2005. Interpreting Pesticide Label Wording. PI-34. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/PI071
Fishel, F.M. 2005. Respirators for Pesticide Applications. PI-77. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/PI114
Fishel, F.M. 2008. EPA Approval of Pesticide Labeling. PI-167. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/PI203
Fishel, F.M. 2009. Personal Protective Equipment for Handling Pesticides. PI-28. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/pi061
Nesheim, O.N., F.M. Fishel and M. Mossler. 2005. Toxicity of Pesticides. PI-13. Gainesville: University of Florida Institute of Food and Agricultural Sciences. https://edis.ifas.ufl.edu/PI008
Signal word as determined by toxicity category.
Examples of signal words based upon toxicity studies.
Typical statements for acute oral toxicity.
Typical statements for acute dermal toxicity.
Typical statements for acute inhalation toxicity.
Typical statements for primary eye irritation.
Typical statements for primary skin irritation.
Typical statements for dermal sensitization.