A cook drops a metal scouring pad near the prep area and a piece breaks off into a pot of sauce unnoticed. This is a source of:

解析

A metal fragment from a scouring pad is a hard foreign object in the food, which makes it physical contamination and something that could cut or choke a guest. It is not a living pathogen (biological), not a cleaning chemical, and not an allergen protein moved from one food to another. Managers should keep such tools away from open food and inspect for stray fragments.