40 CFR 152.161: Definitions.

In addition to the definitions in § 152.3, the following terms are defined for the purposes of this subpart:

(a) Dietary LC50 means a statistically derived estimate of the concentration of a test substance in the diet that would cause 50 percent mortality to the test population under specified conditions.

(b) Outdoor use means any pesticide application that occurs outside enclosed manmade structures or the consequences of which extend beyond enclosed manmade structures, including, but not limited to, pulp and paper mill water treatments and industrial cooling water treatments.