The general criteria for the use of food additives set out in the EU Directives stipulate that additives can be approved only if they present no hazard to human health at the level of use proposed based on the scientific evidence available. The safety evaluation is based on a scientific review of all pertinent toxicological data on the specific additive—both observations in humans and mandatory tests in animals. In the EU, all the evidence is reviewed by the Scientific Committee on Food.

The toxicological tests required by the regulatory authorities include lifetime feeding studies and multigenerational studies that determine how the additive is handled by the body in order to assess any possible harmful effects of the additive or its derivatives. The starting point for establishing the ADI is the determination of the “No Observed Adverse Effect Level” (NOAEL) for the most sensitive adverse effect relevant to human health in the most sensitive species of experimental animal. The NOAEL is, therefore, the highest dietary level of an additive at which no adverse effects were observed in the studies and it is expressed in milligrams of the additive per kilogram of bodyweight per day (mg/kg bodyweight/day). The NOAEL is then divided by a large factor, usually 100, which results in a substantially lower level of permitted intake for man, and a large margin of safety.