Comparison of migration and cumulative risk assessment of antioxidants, antioxidant degradation products, and other non-intentionally added substances from plastic food contact materials

Antioxidants are used in the production of synthetic resins to prevent oxidative degradation. However, non-intentionally added substances (NIAS) and the degradation products of antioxidants may contaminate food contact materials (FCM) and migrate into food. Herein, NIAS and antioxidant degradation products in synthetic resins and their migration into food simulants under various conditions were evaluated. Risk assessment was performed based on the toxicity reference values or with threshold of toxicological concern (TTC) approach. The antioxidant degradation products migrated mainly to fatty-food simulants, with the highest migration in isooctane, followed by n-heptane (similar to or lower than isooctane) and 95 % ethanol. Especially, the migration of 2,4-di-tert-butylphenol was high when the FCM was used for the first time under daily use conditions such as ultraviolet sterilization or heating in a pot, oven, or microwave. In addition, 36 target substances were monitored in 142 products of 18 synthetic resins. Of these, 2,4-di-tert-butylphenol was most sensitively detected. Risk assessment demonstrated that all the investigated substances were below the toxicity reference values. However, the risk associated with polyethylene was relatively high compared to other synthetic resins. The cumulative risks of oxidizing Irgafos 168, (z)-9-octadecenamide, tri-o-tolyl phosphite, tri-p-tolyl phosphite, and 7,9-di-tert- butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione using the TTC approach were calculated to range from 34.81 % to 73.74 %, suggesting that the TTC is a more conservative risk assessment.