What is the name of the agency that investigates human-child contamination in Monsters, Inc.?

The agency that investigates human-child contamination in Monsters, Inc. is the Child Detection Agency.

The Child Detection Agency, usually called the CDA, responds when monsters believe a human child or an object touched by one has entered Monstropolis. Its members wear yellow hazardous-material suits and use containment procedures designed to isolate possible contamination.

The agency’s arrival creates some of the film’s most memorable comic scenes. CDA workers surround Sulley and Mike after Boo’s belongings are suspected of being contaminated, treating ordinary items as dangerous evidence. Their exaggerated emergency response reflects the monsters’ widespread fear of humans.

The CDA is not the same organization as Monsters, Incorporated. Monsters, Inc. is the energy company employing Sulley and Mike, while the CDA is a public authority responsible for contamination incidents. The film later reveals that the danger associated with children is based on a mistaken belief rather than a real biological threat.