What is a critical factor that can affect the toxicity of a pesticide?

The delivery method is indeed a critical factor that can affect the toxicity of a pesticide. This is because different methods of application can influence how much of the pesticide reaches the target organism effectively while also determining the potential for exposure to non-target organisms, including humans, animals, and beneficial organisms in the environment.

For example, pesticides can be applied as sprays, granules, or in bait formulations, each with varying potentials for drift, runoff, and persistence. A method that creates fine droplets may lead to higher drift, increasing the possibility of exposure to sensitive areas or individuals. Conversely, employing a soil application may reduce direct exposure to non-target species but can change the bioavailability of the pesticide to pests. Thus, understanding the delivery method is crucial for mitigating risks and ensuring effective pest management.

The other factors, while important in their own right, do not have the same direct impact on the inherent toxicity of the pesticide itself. Temperature at application, time of day, and area of exposure can influence the effectiveness and behavior of the pesticide but are not as fundamental in determining the pesticide's intrinsic toxicity compared to the delivery method.