What is the potential risk of using outdated or expired pesticides?

The correct choice highlights the significant concern regarding the use of outdated or expired pesticides, which is reduced efficacy and an increased risk of harmful chemical changes. When pesticides pass their expiration dates, their active ingredients may degrade over time due to environmental factors such as temperature, light, and moisture. This degradation can lead to a loss of potency, rendering the pesticide less effective at controlling pests.

Moreover, expired pesticides can undergo chemical transformations that may not only reduce their effectiveness but could also result in the formation of toxic byproducts. These byproducts may pose increased risks to both human health and the environment. Therefore, it is crucial for applicators to use pesticides within their recommended shelf life to ensure safety and effectiveness.

The other choices do not support a correct understanding of the impact of using outdated pesticides. For instance, the notion of increased effectiveness and better chemical stability contradicts the known effects of degradation. Similarly, suggesting enhanced application rates overlooks the critical issues of safety and efficacy when using expired products.