GRAS

Our government food watchdogs can't and don't test every ingredient in every food we consume.

Instead, they maintain a list of ingredients "generally regarded as safe," which goes by the catchy name of GRAS.

According to the Food and Drug Administration, an ingredient is considered safe if there is a "reasonable certainty in the minds of competent scientists that the substance is not harmful under its intended conditions of use."

If the substance does not fall under the GRAS umbrella, it is considered a food additive by the FDA and is subject to a lengthy review and approval process.

Source:  http://www.ochef.com/answers/1642.htm