Cullen wanted me to find a chemical that explodes on contact with air. For a "project."

I found this very oddly phrased article about a scale blowing up during an experiment.

"There is no danger to students," he said. "No freshman is going to be damaged by this."

Um why is he only concerned about freshman?

"We're pretty sure there is no risk of secondary contamination," he said. "It was contained on one person."

Pretty sure? What is that?