Which term describes pest control materials that are relatively nontoxic to people with few environmental side effects?

The term "biorational" specifically refers to pest control materials that are designed to be relatively nontoxic to humans and have minimal environmental side effects. These materials operate on the principle of targeting specific pests while sparing beneficial organisms and humans, thereby promoting a safer and more sustainable approach to pest management. The use of biorational products reflects an understanding of ecology and the interactions within ecosystems, making it a favorable choice for integrated pest management systems.

Biorational products can include materials such as certain plant extracts, insect growth regulators, and pheromones that affect pest behavior without the broad-spectrum lethality associated with traditional chemical pesticides. This makes them particularly valuable in agricultural and horticultural practices where ecological balance is a priority.

Other terms in the options have distinct meanings that do not align with the characteristics of the correct answer. The term "chemical" generally refers to a broader category of substances, many of which can be harmful to humans or the environment. "Biological" mainly describes control agents derived from living organisms, which may not always be non-toxic. "Environmental" is a more generic term that does not specifically address toxicity or the specific attributes of pest control materials.