Their initial findings prompted them to look further. In total, NRDC estimates that about 1,000 of the 10,000 additives used in food today have been added more or less on the down low by companies that don’t want to go through an official review process, don’t want their process known by competitors, or don’t want to face safety questions directly.

Thanks to a Freedom of Information Act (FOIA) request, Maffini and her co-authors got ahold of correspondence between a number of chemical companies and FDA staff members involved in review processes that resulted in withdrawals by the companies. If the FDA rejects a GRAS notice, it informs the company of its safety concerns and makes those concerns public. But if a company withdraws its request for review, the public is left in the dark.

In one example, Maffini and her team looked into a chemical called EGCG, made from an extract of green tea. “We found out the GRAS notice had been submitted to [the FDA] and withdrawn several times. However, it’s really popular in sports drinks, energy drinks, etc.,” she said.

“While the company was basically explaining that these types of purified chemicals were ‘just like green tea,’ FDA had concerns about EGCG,” Maffini said.  In letters to the company, the agency pointed to studies that raised health questions, such as an association with fetal leukemia, and one paper that cited evidence that the chemical caused genetic damage in human cells.

And this is just one example. As the report reads, “companies found their chemicals safe for use in food despite potentially serious allergic reactions, interactions with common drugs, or proposed uses much greater than company-established safe doses.

Of course, NRDC isn’t suggesting that everything added to food under the GRAS rule is unsafe. The point is merely that, under the current system, there is no way for most consumers to know either way. And while many additives appear on ingredient lists, Maffini points out that when additives are used in “incidental” quantities, or included in categories like “natural flavors,” food companies have no obligation to disclose them.

NRDC has made a list of recommendations in the report, including that Congress require the FDA to be informed of GRAS determinations so it can confirm that each chemical’s use in food is, in fact, safe. The organization also wants to see the correspondence between FDA and the companies filing for GRAS review made public, even if they have been withdrawn. In other words, the group is pushing for a more transparent system all around. Until then, NRDC suggests that perhaps GRAS should stand for “generally recognized as secret.”