(GMOs) are excluded and require mandatory authorization. To establish substantial equivalence, the modified product is tested by the manufacturer for unexpected changes to a targeted set of components such as toxins, nutrients, or allergens, that are present in a similar unmodified food. The manufacturer's data is then assessed by a regulatory agency. If regulators determine that there is no significant difference between the modified and unmodified products, then there will generally be no further requirement for food safety testing. However, if the product has no natural equivalent, or shows significant differences from the unmodified food, or for other reasons that regulators may have (for instance, if a gene produces a protein that has not been a food component before), further safety testing may be required. Issues There have been criticisms of the effectiveness of substantial equivalence. See also GRAS - Generally Recognized As Safe, an FDA designation References Notes Food safety Genetically modified organisms in agriculture Biotechnology