Experimental use permits required under Section 5 of FIFRA can be used when conducting experimental field tests on new pesticides on:

Experimental use permits (EUPs) under Section 5 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) are specifically designed to allow for the testing of new pesticide products in defined situations. The criteria for conducting these tests are established to ensure both the safety and effectiveness of the pesticides while limiting environmental impact.

The correct answer states that an experimental use permit is appropriate for trials conducted on 10 or more acres of land or 1 or more acres of water. This is significant because the specified minimum land and water acreage reflects the scale at which the Environmental Protection Agency (EPA) believes testing can be performed without posing excessive risks to the environment, public health, or non-target organisms.

Testing on at least 10 acres allows for a reasonable evaluation of the pesticide's potential effects and efficacy across a representative portion of the landscape. Similarly, testing on at least 1 acre of water is essential for assessing any aquatic impacts, a crucial consideration given the potential for certain pesticides to affect water bodies adjacent to treated lands.

Thus, the regulations ensure that the experimental trials carried out under these permits are sufficiently large to yield reliable data while still maintaining oversight and safety protocols conducive to responsible pesticide use.