The label that comes with a pesticide product is a legal document and must be followed explicitly, otherwise there is a risk of fines and other possible repercussions. Here are the components of a pesticide label, specifically toxicity.

Pesticide toxicity is its ability to cause injury or illness. The measure of this is calculated over time following testing both the active ingredient alone and the formulated product. There are two types of toxicity: chronic and acute. Acute toxicity refers to damage, illness, or reaction to a single exposure to a chemical while chronic toxicity refers to multiple exposures over time.

Acute toxicity occurs in four different ways, and each are tested throughout the process in order to assign a value of potential risk. These manners of exposure include dermal (or absorption through the skin), oral (ingestion), inhalation (breathing in), and contact with eyes. This testing will result in findings which are then expressed as a lethal dose and will be listed as LD₅₀ (lethal dose) or LC₅₀ (lethal concentration).

These values will indicate toxicity in terms of a lethal dose that will kill 50% of the test population. The LD₅₀ is measured in milligrams of chemical per kilogram of the exposed individual and is usually associated with the oral and dermal aspects. LC₅₀ or lethal concentration is expressed in ppm or parts-per-million and generally relates to the inhalation aspect.

The lower either one of these values is indicates the greater toxicity value and therefore the greater care which should be taken. Lethal dosage values have also been assigned to other common everyday products, below is a list for comparison:

• Water: 90,000
• Salt: 3,000
• Vitamin A: 2,000
• THC: 1,270
• Aspirin: 300
• Caffeine: 192
• Nicotine: <60

Remembering that the lower the number, the more toxic the substance is, here are some values for commonly used pesticides:

• Carbaryl (Sevin): 850
• Bifenthrin, Sulfentrazone (Dismiss), and Cypermethrin: >2000
• Imidacloprid (Merit) and Pendimethalin: >5000
• Glyphosate (Roundup, Ranger Pro): 5600

Of course, this does not suggest that these products should be taken in orally, but it does show that their toxicity is similar to many household items. All pesticides can be hazardous to humans, animals, and other organisms so care should be taken when handling, storing, and applying these materials.

These associated values are then used to determine which signal word must be used on the label. The signal words are Danger, Warning, and Caution, and are categories of a toxicity range that will give you the first clue as to the level of risk in using the product.

• Danger (Category I): Highly toxic - LD₅₀ up to 50
• Warning (Category II): Moderately toxic - Oral LD₅₀ 50 – 500
• Caution (Category III): Slightly toxic - Oral LD₅₀ 500 – 5000

Other factors are involved including dermal and inhalation values along with potential damage to eyes. Any product that has an LD₅₀ higher than 5000 and does not present any other major risk will fall into category IV or considered very low toxicity. For example, the insecticide Acelepryn does not require the use of a signal word on the label.

We'll discuss other important details and bits of information in the future. For now, make sure to read and follow all label instructions when using pesticides and remember to apply them safely. Here's a valuable link on pesticide exposure and first aid from the University of Kentucky.

Please contact us with any questions or suggestions for future topics.