Safe Pesticide Handling and Signal Words

Why is pesticide handling important?

Pesticides are toxic materials which must be handled with extreme caution. Pesticides that are packaged in their concentrated form and which must be diluted before application are of most concern.In particular, operations which involve mixing and loading of pesticides are considered to be the most hazardous processes when a pesticide is to be applied. During mixing and loading of pesticides, the possibility of direct exposure to spills and splashes is highest.

Direct exposure to a pesticide can be via inhalation, ingestion, and contact with the skin. If exposure is in significant amounts, the pesticide can be toxic. However, not all pesticides are equally toxic.

With proper handling and application, pesticides rank among the safest production aids used. They undergo exhaustive manufacturer’s tests and pass stringent label requirements before being approved and registered for market by the US Environmental Protection Agency (EPA). In addition, pesticide residues and their effects are carefully monitored or surveyed. Teams of scientists maintain surveillance on air and water quality, crops, soils, animals, and humans to ensure that dangerous levels of pesticides are not accumulating in the environment.

Pesticide toxicity and exposure

Pesticides are toxic substances which can cause injury or lead to death depending on the length of exposure someone has had. Toxicity is the inherent capability of the pesticide to produce injury or death. Ultimately, the hazardous nature of pesticides depends upon their toxicity and the length of exposure someone has had to the pesticide.

As a guide, the US EPA requires pesticide containers and labels to contain signal words that denote the relative toxicity of the pesticide product.

What are the signal words on pesticide labels?

Every pesticide label must contain a signal word that provides a clue to the potential user as to how dangerous the product is to humans. Knowing the hazard potential of a product helps users choose the proper protective measures for themselves,all others who may be exposed, and the environment.

The signal word is found in large letters on the front part of the pesticide label immediately following the ‘Keep Out of Reach of Children’ statement which must appear on every pesticide label.

Why must pesticides be kept out of the reach of children?

Children are particularly susceptible to the hazards associated with pesticides. Children absorb more pesticide than adults relative to body weight and children also have developing organ systems that are more vulnerable and less able to detoxify hazardoussubstances.

The pesticide signal words are CAUTION, WARNING, and DANGER-POISON.

• CAUTION signals that:
  • The product is slightly toxic orally, dermally, or through inhalation and causes slight eye or skin irritation.
  • An ounce to more than a pint taken orally could kill an average-sized adult.

• WARNING signals that:
  • The product is moderately toxic orally, dermally, or through inhalation and causes moderate eye and skin irritation.
  • A teaspoonful to a tablespoonful by mouth could kill an average-sized adult.

• DANGER-POISON signals that:
  • The pesticide is highly toxic.
  • The skull and crossbones symbol will be found on the label.
  • A taste to a teaspoonful taken orally could kill an average-sized adult.
  • The word DANGER alone may be found on a few labels where the pesticide is corrosive or causes severe eye and skin burns but is not highly toxic orally or through inhalation.

Read the label

• Read and follow all recommendations on the label for safe handling and use.
• The signal words are assigned on the basis of the highest measured toxicity, be it oral, dermal, or inhalation, effects on the eyes and external injury to the skin.
• Signal words are based on the total formulation and not active ingredient. Therefore certain products may have the same active ingredient but may bear different signal words in different formulations.
• Signal words indicate the relative toxicity of a pesticide formulation. You should always read the pesticide label to determine what Personal Protective Equipment (PPE) you are required to wear for that product.

Further Reading

• Pesticide Safety: 10 Things That Must be on a Pesticide Label
• Pesticide Safety: Personal Protective Equipment (PPE)

References

• Bohmont, B.L. 2007. The Standard Pesticide User’s Guide – 7^th Pearson Prentice Hall. Pp. 201-245.
• MSU Extension. Personal Protective Equipment for Pesticide Applicators. Montana State University, Pesticide Education Program.  [Accessed June 29, 2022].