Are insect growth regulators considered harmless to humans and other vertebrates?

Insect growth regulators (IGRs) are designed to disrupt the normal development of insects by targeting specific biological processes related to growth and reproduction. Their mode of action is generally selective, meaning they affect insects more than other organisms. This selectivity is due to the differences in physiology and biochemistry between insects and vertebrates, including humans.

The concept that IGRs are considered relatively harmless to humans and other vertebrates is based on this targeted action. While it is always important to handle any pesticide product according to label instructions and safety guidelines, the lower toxicity to non-target organisms, such as mammals, contributes to the perspective that they are safer options in pest management.

This understanding of the specificity of IGRs is why the assertion in the correct answer highlights their target action as a key reason for their lower risk to humans and vertebrates, creating a stronger basis for their use in agriculture and pest control.