The Hershey Co. and Trader Joe’s both are facing class-action lawsuits concerning the levels of lead and cadmium in their dark chocolate products.

Making sure that people walking the aisles don’t tamper with product — and catching them when they do and making sure they never do it again — is crucial to assuring loyal customers that their grocery store is a safe place to shop and one where maintaining the integrity of the products they buy is paramount.