Platinum migration and dietary exposure associated to commercial silicone food containers for microwave or oven use

Reusable silicone food contact materials (FCMs) for cooking have gained popularity. In this work, we have found Pt contents of 2.09 ± 0.03, 0.63 ± 0.07 and 0.65 ± 0.03 mg kg⁻¹ in a commercial silicone cooking case, muffin baking mold and baby training cup, respectively, derived from Pt catalyst residues. The Pt migration to food simulants and real foods was evaluated during the repeated use of these FCMs, under oven or microwave heating, according to European Commission guidelines. Appreciable Pt migration was found by ICPMS analysis, especially for fatty food simulants. The migrations obtained for the third use were: 3.6 ± 0.7 µg Pt kg⁻¹ for salmon baked in the cooking case at 180 ºC and 4.0 ± 0.7 µg Pt kg⁻¹ for microwave heating at 800 W; 0.43 ± 0.07 µg Pt kg⁻¹ for muffins prepared at 180 ºC in the baking molds; and 0.05 ± 0.02 µg Pt kg⁻¹ for chocolate milk under microwave heating in the baby cup. 3-kDa and 0.22-µm filtration of the extracts revealed the presence of both Pt-containing particles and soluble Pt, the latter presenting a higher bioavailability. Significant release of silicone microparticles (5–25 µm) to 95 % EtOH extracts was observed by SEM analysis, especially for the baby cup. Pt nanoparticles (PtNPs) were neither detected in the silicone nor in the extracts by SEM and single particle-ICPMS analysis. The Pt intakes due to the daily use of these FCMs lie within tolerable limits, but represent a significant source of Pt exposure.