Signal Words On A Pesticide Label

When shopping for pesticides, look closely at the product label. On the front panel, you will find what’s called “signal words” describing the short-term toxicity (acute toxicity) of the formulated pesticide on most pesticide products. The signal words are required by the EPA to be printed in all capital letters alerting users to the health hazards of a particular pesticide.

These signal words represent the determined toxicity (poisonous) levels of pesticides. The order of least to the highest levels include “Caution”, “Warning” and “Danger”. The only pesticide products not required to display the operative signal word are those that fall into the lowest toxicity category by all routes of exposure which includes oral, dermal, inhalation, and other effects like eye and skin irritation.

A goal of Pest Control Management is choosing a pesticide with the least toxicity to people that is still efficient in controlling a targeted pest. Regardless of the signal word on the label, it is crucial to know that every pesticide, regardless of how low the toxicity. has the potential to poison people and pets depending upon the exposed dosage.

Signal Word Descriptions

CAUTION. means the pesticide product is slightly toxic if eaten, absorbed through the skin, inhaled, or it causes slight eye or skin irritation.

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

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, the word “POISON” must also be included in red letters on the front panel of the pesticide product label.

How Signal Words Are Determined

The manufacturer of a pesticide performs research on laboratory animals to determine the toxicity of the formulation. The required research and studies by the EPA include oral exposure, dermal exposure, inhalation and exposure to eyes and skin for irritation.

Based on various studies, the EPA requires that the highest toxicity be used as the signal word. As an example, if the pesticide product demonstrated low toxicity when eaten, moderate toxicity when inhaled, and high toxicity when applied to skin, the EPA would assign the signal word DANGER, based on the most sensitive route of entry since the highest toxicity level was the skin study.

Toxicity Category Chart

Pesticide Toxicity Category Chart Showing Toxicity Levels Determining Signal Words Click to Enlarge

Restricted Use Pesticides (RUP’s)

Some pesticides are ‘Restricted Use Pesticides” (RUP) and can only be purchased by certified pesticide applicators and must be marked on the product label. Certified applicators are required to undergo specialized training, testing and continuing education.

Safest Approach To Using Pesticides

If you decide to use pesticides, always use the least toxic choice that will be the most productive in controlling pests. Do not use a more toxic pesticide until all other options have failed. If you use a pest control service, always discuss safety options and ask to see the product label or product material data sheet.

Relevant Sources of Information