Safety assessment of the use of recycled high-density polyethylene in cosmetics packaging based on in silico modeling migration of representative chemical contaminants for dermal sensitization and systemic endpoints

A safety assessment of recycled high-density polyethylene (rHDPE) in cosmetic packaging was performed based on guidelines published by the European Food Safety Authority (EFSA) on the use of recycled plastics for food packaging. EFSA guidelines require demonstration that the concentration of selected representative chemical contaminants in recycled plastic resulting from exposure from food is lower than the threshold of toxicological concern (TTC) for genotoxic substances of 0.0025 µg/kg bw/day. To investigate the highest concentration (Cmod) of representative chemical contaminants, that would not exceed the genotoxic TTC, when migrating from rHDPE packaging to foodstuffs, used as cosmetic formulation surrogates, we used mathematical modeling software (MIGRATEST®EXP). The Cmod values of representative chemical contaminants were then compared with the EFSA-reported residual concentration (Cres) of each contaminant in the rHDPE. For each of the cosmetic product/packaging combinations evaluated, we found that the modeled values were clearly lower for Cmod than Cres, i.e., the recycling process could effectively reduce potential contaminants of rHDPE to levels that would not result in daily consumer exposure from cosmetic use exceeding the genotoxic TTC. For skin sensitization, we modeled a worst-case scenario and assumed 100 % of each representative chemical contaminant migrates into the cosmetic formulation from rHDPE. We then calculated the consumer exposure level for each contaminant based on the dose per unit area and compared it with the dermal sensitization threshold (DST) for reactive materials, which is 64 µg/cm². In each case, we demonstrated that the migration of each representative chemical contaminant from rHDPE into each cosmetic formulation was far below the DST, confirming that there is no appreciable risk of sensitization for protein-reactive chemicals. In conclusion, these data support the safe use of rHDPE in the packaging of cosmetic products for leave-on and rinse-off applications.