What kind of exposure typically leads to sensitization?

Sensitization typically occurs when an individual first encounters an allergen, resulting in an initial immune response that is often non-allergic in nature. This first exposure primes the immune system, leading to a heightened sensitivity. Future exposures can then trigger allergic reactions, as the body has been sensitized to the allergen.

In this context, the initial non-allergic reactions refer to the body's immune response setting the stage for a more significant reaction upon subsequent exposures. It’s a crucial principle in understanding how allergens work within the realm of pesticides and similar substances. Therefore, this initial reaction is what leads to sensitization, making it the most relevant choice for understanding the process.