Migration of monomers, plastic additives, and non-intentionally added substances from food utensils made of melamine–formaldehyde resin following ultraviolet sterilization

Ultraviolet (UV) sterilization of kitchenware is considered environmentally friendly and economical. However, there are many cases of extended UV irradiation, which raises concerns about the release of hazardous substances. Here, we investigated the migration of monomers, plastic additives, and non-intentionally added substances (NIAS) from food utensils made of melamine–formaldehyde resin into food simulants after UV irradiation for up to 7 d. The migration of monomers (melamine and formaldehyde) was analyzed using a high-performance liquid chromatograph with a diode array detector. When irradiated with a UV lamp for 7 d, the release of melamine from food utensils made of melamine–formaldehyde resins increased by up to 85-fold compared with that from the unexposed samples. Formaldehyde release increased up to 4-fold after UV exposure. UV exposure led to a sustained increase in melamine migration in a time-dependent manner. Formaldehyde release also increased on the first day, but plateaued after seven days of exposure. Safety assessment demonstrated that there is a low risk of melamine and formaldehyde exposure of up to 11.78% and 7.95%, respectively, compared with the tolerable daily intake. Non-target screening analysis of plastic additives and NIAS from melamine–formaldehyde resin and other synthetic resins was performed using high-performance liquid chromatography quadrupole time-of-flight mass spectrometry. Exposure of melamine–formaldehyde resin to UV for 7 d drastically increased the release of plastic additives and NIAS. In contrast, for other synthetic resins (polypropylene, polyamide, polyethylene, polyethylene terephthalate, and silicone), the peaks of these compounds disappeared or decreased after UV exposure, indicating that the melamine–formaldehyde resin is less resistant to UV degradation than other synthetic resins.