EPA Signal Words

What Are Signal Words?

Signal words are found on pesticide product labels, and they describe the acute (short-term) toxicity of the formulated pesticide product. The signal word can be either: DANGER, WARNING or CAUTION. Products with the DANGER signal word are the most toxic.

The Environmental Protection Agency (EPA) requires a signal word on most pesticide product labels. They also require it to be printed on the front panel, in all capital letters, to make it easy for users to find. The only pesticide products that are not required to display a signal word are those that fall into the lowest toxicity category by all routes of exposure (oral, dermal, inhalation, and other effects like eye and skin irritation).

CAUTION

Products with the signal word CAUTION are lower in toxicity. A “CAUTION” label means the pesticide product is slightly toxic if eaten, absorbed through the skin, inhaled, or it causes slight eye or skin irritation.

WARNING

“WARNING” indicates the pesticide product is moderately toxic if eaten, absorbed through the skin, inhaled, or it causes moderate eye or skin irritation.

DANGER

“DANGER” means that the pesticide product is highly toxic by at least one route of exposure. It may be corrosive, causing irreversible damage to the skin or eyes. Alternatively, it may be highly toxic if eaten, absorbed through the skin, or inhaled. If this is the case, then the word “POISON” must also be included in red letters on the front panel of the product label.

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.

Disclaimer: Exposure to almost any pesticide can cause illness. Some pesticides are so toxic even a small quantity can be dangerous to the operator, bystanders, pets, livestock and wildlife. To apply any pesticide safely, your most important source of information is the label on the container. Read and follow the directions on it.

Please read all pesticide labels prior to use. The information contained at this web site is not a substitute for a pesticide label. Trade names used herein are for convenience only; no endorsement of products is intended, nor is criticism of unnamed products implied. Most of the agri-chemical and pesticide information is historical in nature and may no longer be applicable.