An Explaination of (GRAS) or Generally Recognized As Safe

Wikipedia, the free encyclopedia states that:
Generally Recognized as Safe (GRAS) is a United States of America Food
and Drug Administration (FDA) designation that a chemical or substance
added to food is considered safe by experts, and so is exempted from
the usual Federal Food, Drug, and Cosmetic Act (FFDCA) food additive
tolerance requirements.

GRAS exemptions are granted for substances that are generally
recognized, among experts qualified by scientific training and experience to
evaluate their safety, as having been adequately shown through scientific
procedures (or, in the case of a substance used in food prior to
January 1, 1958, through either scientific procedures or through experience
based on common use in food) to be safe under the conditions of their
intended use.

The substance must be shown to be "generally recognized" as safe under
the conditions of its intended use. The proponent of the exemption has
the burden of proving that the use of the substance is "generally
recognized" as safe. To establish such recognition, the proponent must show
that there is a consensus of expert opinion regarding the safety of the
use of the substance. However, the existence of a severe conflict
among experts regarding the safety of a substance precludes a finding of
general recognition.

When a use of a substance does not qualify for the GRAS exemption that
use of the substance is subject to the premarket approval mandated by
the FFDCA. In such circumstances, the FDA can take enforcement action to
stop distribution of the food substance and foods containing it on the
grounds that such foods are or contain an unlawful food additive. [1]

A GRAS designation typically exists in one of three forms:

Self-affirmed. The manufacturer of this chemical or substance had
performed all necessary research, including the formation of an expert panel
to review safety concerns, and is prepared to use these findings to
defend its product’s GRAS status.
FDA-pending. The manufacturer has performed all the aforementioned due
diligence, and submitted to the Food & Drug Administration for GRAS
approval.
No comment. The FDA has reviewed a product’s GRAS claim and responded
with "no comment," i.e. no further challenges on the product’s GRAS
status.