National Uniformity for Food Act of 1998 - Amends the Federal Food, Drug, and Cosmetic Act (FDCA) to prohibit any State or political subdivision from establishing or continuing in effect as to any food in interstate commerce any requirement for food labeling or food that is not identical to specified FDCA provisions.

Prohibits any State or political subdivision from establishing or continuing in effect any notification requirement for a food that provides for a warning concerning the food's safety that is not identical to FDCA provisions. Allows a State to petition for an exemption and for a national standard regarding any requirement under the FDCA or the Fair Packaging and Labeling Act relating to food regulation. Allows a State to establish a requirement that would otherwise violate FDCA provisions relating to national uniform nutrition labeling or this paragraph if the requirement is needed to address an imminent hazard to health that is likely to result in serious adverse health consequences and if other requirements are met.