Pesticide products are regulated by laws meant to minimize unintended impact on humans, the environment, and property. Pesticide product labels are subject to detailed regulations including the requirement to use a “signal” indicating the acute toxicity of the product. The four signals are (1) Caution, (2) Warning, (3) Danger, and (4) Danger-Poison (with a skull and crossbones symbol). While an uninformed observer might view these terms as merely emphasizing a need to be careful, these are actually terms of art indicating, in order of increasing toxicity, categories of threats to human health.
(1) Toxicity Category I. Any pesticide product meeting the criteria of Toxicity Category I for any route of exposure must bear on the front panel the signal word “DANGER.” In addition, if the product is assigned to Toxicity Category I on the basis of its oral, inhalation or dermal toxicity (as distinct from skin and eye irritation), the word “Poison” must appear in red on a background of distinctly contrasting color, and the skull and crossbones symbol must appear in immediate proximity to the word “Poison.”
(2) Toxicity Category II. Any pesticide product meeting the criteria of Toxicity Category II as the highest category by any route of exposure must bear on the front panel the signal word “WARNING.”
(3) Toxicity Category III. Any pesticide product meeting the criteria of Toxicity Category III as the highest category by any route of exposure must bear on the front panel the signal word “CAUTION.”
(4) Toxicity Category IV. A pesticide product meeting the criteria of Toxicity Category IV by all routes of exposure is not required to bear a signal word. If a signal word is used, it must be “CAUTION.”40 CFR § 156.64(a)(1)-(4)
The toxicity categories are clearly defined according to the acute hazards presented by the substance and the label must make this clear. But without an understanding of the technical language and the threats presented, the significance of the words could be lost on the one exposed to the product.
Just as the words Caution, Warning, and Danger on pesticide labels indicate more than the plain meaning of those words, so it is with many terms of art. But in order to understand the full meaning and implication of the words used (or those not used), subject-matter background or at least expert guidance is often necessary. Life and death could be at stake.