Reactions of epoxide monomers in food simulants used to test plastics for migration

The reactions of four epoxides used as monomers for food contact plastics were studied in the food simulants distilled water, 15% aqueous ethanol, 3% aqueous acetic acid and olive oil. Loss of the parent substance and formation of products was monitored to establish the transformation products to be expected in each simulant following migration testing of plastics. Each epoxide was stable in olive oil but suffered extensive loss in the three aqueous simulants. Reaction half-lives were from < 1 to 10 h in aqueous acetic acid, 25-63 h in distilled water, and 33-87 h in aqueous ethanol simulant. Hydrolysis to the diol was the main reaction pathway. Epoxide ring opening in aqueous ethanol simulant gave the diol and also the diol monoethyl ether. It is concluded that, for aqueous simulants and by implication for most foods, testing plastics against specific migration limits for epoxides is not likely to give reliable results due to their reactivity. The present EC mode of control for these reactive monomers, via compositional limits in food contact plastics, is more practical since the hydrolysis products are less toxic than the parent epoxide.