Effects of ionizing radiation on food contact materials

FDA's Office of Food Additive Safety is responsible for the evaluation of food additive petitions and pre-market notifications requesting approval of new food contact materials for irradiation. Our lab supports that review process by conducting research to identify and quantify the products formed in food contact polymers after exposure to ionizing radiation and then determining whether any of these compounds migrate into food. A major objective of this research is to assist in the development of guidance to manufacturers seeking FDA approval to irradiate their products. Different polyesters, polyamides, a high-density polyethylene, and an ethylene vinyl alcohol copolymer were evaluated before and after exposure to different levels of gamma and electron-beam radiation. Volatile chemicals were isolated from the test materials using static headspace sampling and analyzed by gas chromatography with mass selective detection. Semi-volatile and non-volatile chemicals were extracted from the test materials using a variety of solvents including n-heptane, a fatty food simulating solvent, and the extracts were analyzed using high performance liquid chromatography with mass selective detection, The extracts containing semi-volatiles were also analyzed by gas chromatography with mass selective detection. Most of the chemicals found are thought to be products of the polymerization process or conversion of the polymer(s) into a finished package, and breakdown products of polymer additives. Although exposure to ionizing radiation increases the concentration of some of these chemicals and decreases the concentration of other chemicals, few of the chemicals determined are thought to be chemicals specifically formed by ionizing radiation. Results of these analyses and data on the migration of some of the chemicals are presented.