Migration of 35 Siloxanes from Silicone Food Contact Materials in China and Their Potential Exposure Assessment

Silicone food contact materials (FCMs) pose potential health risks due to the migration of siloxanes. This study presents a comprehensive migration profiling of 35 siloxanes (cyclic D3-D22 and linear L2-L14) from 30 silicone FCMs, with migration tests rigorously conducted under worst-case intended-use scenarios to ensure conservative and reliable exposure estimates. Methodological innovations include an expanded analytical scope, age-stratified exposure assessment across seven age groups, and a multi-tiered risk evaluation framework. The results reveal that migration behaviors were affected by simulant polarity, siloxane solubility, and silicone thermal stability. The risk evaluation framework integrates aggregate migration limits for total cyclic (D3-D13) and total cyclic plus linear siloxanes (D3-D13, L3-L13), complemented by individual siloxane assessment via Risk Quotient (RQ) and Threshold of Toxicological Concern (TTC) approaches. While the total migration of cyclic siloxanes exceeded the proposed action limit of 12 mg/kg for adults in several samples and 2 mg/kg for children in most samples, granular assessment revealed divergent risks: Cyclic D4 and D5 showed negligible risk (RQ < 5). In contrast, D3 migration posed a potential concern (RQ > 5), especially for individuals aged >13 years. Notably, the estimated exposures to 14 siloxanes with low molecular weight (<1000 Da), including highly prevalent D6 and L12 with detection frequency >90%, exceeded the TTC threshold across all age groups, highlighting unaddressed risks that are not captured by aggregate action limits. This work underscores the need for substance-specific, age-specific risk evaluations and regulatory updates for silicone FCMs.