防止有害食物上市是FDA的责任。想食品里头添加东西，你要么向ＦＤＡ申请GRAS　exemption，要么找ＦＤＡ进行premarket approval，如果前者宽松，就会出现安全漏洞。

In that document, FDA not only reviewed the regulations defining
GRAS and administering the GRAS process, but also proposed
replacing the then-existing voluntary but resource-intensive GRAS
Affirmation Petition process the agency put in place in the 1970’s,
with a more streamlined voluntary GRAS notification process. In
the 1997 notice, the agency made it clear that both food additives
and GRAS ingredients require the same strength of evidence of
safety. For food additives, the FDA reviews and approves the use
based on evidence supplied by the petitioner in the form of a petition.
For GRAS ingredient uses, the extra added element is the general
recognition required that the available safety evidence is both
widely known (e.g., available in the published literature or in commonly
accessible knowledge sources such as text books) and that
there is a consensus among qualified experts about that evidence
in support of the safe use of the material in food. In fact, the GRAS
criteria are in some ways more difficult to satisfy than the food
additive criteria because of the additional requirement of public　availability of the data and general recognition and acceptance of
a safety conclusion based on those data.