University of FloridaSolutions for Your Life

Download PDF
Publication #PI-100

Pesticide Labeling: Signal Words1

Frederick M. Fishel2

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.

Introduction

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 products label has no signal word displayed? The signal word conveys a message to the products 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 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, 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, 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, EPA requests that the “POISON” and the skull and crossbones symbol appear near the signal word “DANGER” (Figure 1).

Figure 1. 

"POISON" and the skull-and-crossbones symbol shoould appear near the signal word "DANGER".


[Click thumbnail to enlarge.]

Additional Information

Tables

Table 1. 

Toxicity categories.

Study

Category I

Category II

Category III

Category IV

Acute oral

Up to and including 50 mg/kg

>50 through 500 mg/kg

>500 through 5,000 mg/kg

>5,000 mg/kg

Acute dermal

Up to and including 200 mg/kg

>200 through 2,000 mg/kg

>2,000 through 5,000 mg/kg

>5,000 mg/kg

Acute inhalation*

Up to and including 0.05 mg/liter

>0.05 through 0.5 mg/liter

>0.5 through 2 mg/liter

>2 mg/liter

Primary eye irritation

Corrosive (irreversible destruction of ocular tissue) or corneal involvement or irritation persisting for more than 21 days

Corneal involvement or other eye irritation clearing in 8-21 days

Corneal involvement or other eye irritation clearing in 7 days or less

Minimal effects clearing in less than 24 hours

Primary skin irritation

Corrosive (tissue destruction into the dermis and/or scarring)

Severe irritation at 72 hours (severe erythema or edema)

Moderate irritation at 72 hours (moderate erythema)

Mild or slight irritation at 72 hours (no irritation or slight erythema)

*4-hour exposure.

Table 2. 

Signal word as determined by toxicity category.

Toxicity category

Signal word

I

DANGER

II

WARNING

III

CAUTION

IV

None required

Table 3. 

Examples of signal words based upon toxicity studies.

Type of study

Product A

Product B

Product C

Product D

Product E

Acute oral

III

IV

I*

III

II

Acute dermal

IV

III

III

IV

II

Acute inhalation

III

IV

III

III

II

Primary eye

III

II

I

I

II

Primary skin

IV

IV

II

IV

II

Contains >4% methanol

No

No

No

No

Yes**

Signal word

CAUTION

WARNING

DANGER

DANGER

DANGER

*Product C must also bear the skull and crossbones symbol in close proximity to the word “POISON” which must appear in red on a contrasting background due to acute oral toxicity.

**Product E must also bear the skull and crossbones symbol in close proximity to the word “POISON” which must appear in red on a contrasting background due to its formulation containing at least 4% methanol.

Table 4. 

Typical statements for acute oral toxicity.

Toxicity category

Signal word

Statements

I

DANGER-POISON Skull and crossbones required*

Fatal if swallowed. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco.

II

WARNING

May be fatal if swallowed. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco.

III

CAUTION

Harmful if swallowed. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco.

IV

CAUTION (optional)

No statements are required. However, manufacturers may choose to use category III labeling.

*For products containing >4% methanol, EPA believes that in order to mitigate potential risk the following statement should be added to the label: “Methanol may cause blindness.”

Table 5. 

Typical statements for acute dermal toxicity.

Toxicity category

Signal word

Statements

I

DANGER-POISON Skull and crossbones required

Fatal if absorbed through skin. Do not get in eyes, on skin, or on clothing. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Wear (appropriate protective clothing listed here). Remove and wash contaminated clothing before reuse.

II

WARNING

May be fatal if absorbed through skin. Do not get in eyes, on skin, or on clothing. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Wear (appropriate protective clothing listed here). Remove and wash contaminated clothing before reuse.

III

CAUTION

Harmful if absorbed through skin. Avoid contact with skin, eyes or clothing. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Wear (appropriate protective clothing listed here). Remove and wash contaminated clothing before reuse.

IV

CAUTION (optional)

No statements are required. However, manufacturers may choose to use category III labeling.

Table 6. 

Typical statements for acute inhalation toxicity.

Toxicity category

Signal word

Statements

I

DANGER-POISON Skull and crossbones required

Fatal if inhaled. Do not breathe (dust, vapor, or spray mist listed here). Wear (appropriate respiratory protection listed here). Remove and wash contaminated clothing before reuse.

II

WARNING

May be fatal if inhaled. Do not breathe (dust, vapor, or spray mist listed here). Wear (appropriate respiratory protection listed here). Remove and wash contaminated clothing before reuse.

III

CAUTION

Harmful if inhaled. Avoid breathing (dust, vapor, or spray mist listed here). Remove and wash contaminated clothing before reuse.

IV

CAUTION (optional)

No statements are required. However, manufacturers may choose to use category III labeling.

Table 7. 

Typical statements for primary eye irritation.

Toxicity category

Signal word

Statements

I

DANGER

Corrosive.* Causes irreversible eye damage. Do not get in eyes or on clothing. Wear (appropriate protective eyewear such as goggles, face shield, or safety glasses listed here). Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Remove and wash contaminated clothing before reuse.

II

WARNING

Causes substantial but temporary eye injury. Do not get in eyes or on clothing. Wear (appropriate protective eyewear such as goggles, face shield, or safety glasses listed here). Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Remove and wash contaminated clothing before reuse.

III

CAUTION

Causes moderate eye irritation. Avoid contact with eyes or clothing. Wear (specify protective eyewear, if appropriate, here). Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco.

IV

CAUTION (optional)

No statements are required. However, manufacturers may choose to use category III labeling.

*The term “corrosive” is not required if corrosive effects were not observed during the study.

Table 8. 

Typical statements for primary skin irritation.

Toxicity category

Signal word

Statements

I

DANGER

Corrosive. Causes skin burns. Do not get in eyes, on skin, or on clothing. Wear (appropriate protective clothing and gloves listed here). Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Remove and wash contaminated clothing before reuse.

II

WARNING

Causes skin irritation. Do not get on skin or on clothing. Wear (appropriate protective clothing and gloves listed here). Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Remove and wash contaminated clothing before reuse.

III

CAUTION

Avoid contact with skin or clothing. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or using tobacco. Wear (appropriate protective clothing and gloves listed here).

IV

CAUTION (optional)

No statements are required. However, manufacturers may choose to use category III labeling.

Table 9. 

Typical statements for dermal sensitization.

Study results

Statement

Product is a sensitizer or is positive for sensitization.

Prolonged or frequently repeated skin contact may cause allergic reactions in some individuals.

Product is not a sensitizer or is negative for sensitization.

No labeling is required for this result.

Footnotes

1.

This document is PI-100, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date January 2006. Revised February 2009. Reviewed January 2012. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Frederick M. Fishel, professor, Agronomy Department, and Director, Pesticide Information Office; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

Use pesticides safely. Read and follow directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.