Any chemical substance is toxic if it is ingested or absorbed in excessive amounts.
Table salt, for example, if consumed in excess, can be toxic. The degree of danger or hazard when using a pesticide is determined by multiplying toxicity times exposure. The designation given to a pesticide indicating its relative level of toxicity is called the Lethal Dose, or LD 50 value. This value identifies the dosage rate necessary to kill 50 percent of a test population. Lethal dose is expressed in milligrams of chemical per kilogram of body weight of the test population.