In 1972, the FDA designed a special transitional category for food-use substances whose safety has been called into question.255 The new procedural regulations emerged from the FDA's successful experience with issuing an interim order concerning brominated vegetable oil, a stabilizer in fruit-flavored beverages.256 As it explained in the preamble to the regulation:
The Commissioner recognizes that, with the vast increase in the quantity of scientific testing and in the sophistication of test methodology, there is virtually no[ ] natural or synthetic food substance that cannot be questioned on some technical ground. It would be impossible to require elimination from the food supply of every food substance for which such scientific questions have been or will be raised.257
The agency may promulgate an "interim" food additive regulation "when new information raises a substantial question about the safety or functionality of the substance but there is a reasonable certainty that the substance is not harmful and that no harm to the public health will result from the continued use of the substance for a limited period of time while the question raised is being resolved by further study."258 In promulgating an interim regulation, the FDA must abide by the same rulemaking procedures applicable to the issuance of a final food additive order,259 but the interim order is summarily revocable. The regulation may demand compliance "with whatever limitations the Commissioner deems to be appropriate under the circumstances.''260
In every case, a promise by one or more sponsors to undertake additional studies represents the primary condition for continued marketing. 261 Within 60 days after the effective date of an interim food additive regulation, an interested person must certify that "adequate and appropriate" studies have been undertaken to resolve the questions raised about the substance; otherwise, an order shall be published immediately to revoke the interim food additive regulation.262 In the preamble, the FDA emphasized that the purpose of an interim food additive regulation "is to assure that prompt action is taken to resolve the issue."263 Progress reports are due every six months; otherwise, the same revocation sanction may apply.264 "Promptly upon completion of the studies undertaken on the substance, the Commissioner will review all available data, will terminate the interim food additive regulation, and will either issue a food additive regulation or will require elimination of the substance from the food supply."265
During the past 20 or so years, the FDA has regulated the following substances as interim food additives: acrylonitrile copolymers, mannitol, brominated vegetable oil, and saccharin.266 In each case, the regulations called for additional toxicological studies, though with different levels of specificity.267 The original interim food additive regulation for saccharin contained a 17-month sunset provision,268 but the FDA subsequently revised the regulation to delete any expiration date. 269
With the exception of nitrites used in certain curing premixes,270 no previously listed interim food additive has been made subject to permanent restrictions or an outright prohibition. The FDA recently revised the mannitol regulation to authorize an additional method of manufacture without commenting on the fact that the "interim" regulation remained in place more than two decades after promulgation. 271 Apart from saccharin, which is the subject of a continuing regulatory moratorium imposed by Congress,272 the FDA's inaction on these interim food additives seems inexplicable.273 Courts have invalidated a similar "holding category" designed by the agency to authorize the continued use of an OTC drug product while awaiting the results from further studies of an active ingredient.274 Nevertheless, the FDA and the industry seem content to leave these particular additives in what has evolved into a semi-permanent regulatory limbo.