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"Caution" Signal-Word Rule Change

Mark Mohr, Ag. Eng. Dept., Extension Specialist, 360t Agricultural Engineering Sciences Building, (MC-644), Urbana, IL, (217) 333-9418, mmohr@age.uiuc.edu

The US EPA has changed the signal-word requirements for the least toxic category of pesticides, those that fall into toxicity category IV. Starting February 12, 2002, if a pesticide falls into the least toxic category for all routes of exposure–such as oral, dermal, and inhalation–the product label will no longer be required to show the signal word "caution," though the word may be used by the manufacturer voluntarily. The child-hazard warning is still required on all products, and other uses of signal words stay the same.

Signal words are assigned to a product based on the toxicity of the product. There are four toxicity categories, and a signal word is assigned to each of the first three categories. Ranked from most to least toxic, the signal words are "danger" (or "danger—poison"), "warning," and "caution," for categories I, II, and III, respectively.

Under the old signal-word rules, pesticides in category IV were also required to bear the word "caution." The EPA sought to clarify the difference between categories III and IV by using a different signal word for the least toxic category. Because no suitable word could be found to indicate a lower risk from toxicity than "caution," the new rules make the use of the signal word "caution" optional on the labels of products in toxicity category IV.