Why are preharvest intervals legally required?

Preharvest intervals are legally required primarily to prevent the harvesting of produce that contains illegal residues from pesticides or other agricultural chemicals. These intervals specify the minimum time that must pass between the last application of a chemical and the harvest of the crop. This is critical for ensuring food safety, as residual chemicals can pose health risks to consumers. By establishing these intervals, regulatory authorities aim to protect public health and maintain agricultural integrity.

The other options do not address this crucial aspect of safety and regulatory compliance, focusing instead on aspects like growth promotion, yield increase, or pest resistance, which are not the primary concern of preharvest regulations.