Strategy proposal using QSAR models to approach mutagenicity assessment of non intentionally added substances in recycled plastic resins.

Context: Transition to the use of recycled plastics raises an issue concerning safety assessment of Non Intentionally Added Substances (NIAS). To assess the mutagenic potential of the recycled polyethylene impurities and to evaluate the need to perform in vitro assays on recycled resins, this study lies in identifying existing NIAS associated with recycled Low/High Density Polyethylene and assessing the mutagenicity data-gaps by employing in silico tools.

Methods: Quantitative Structure-Activity Relationship (QSAR) models predicting Ames mutagenicity were selected from literature, then NIAS were run to 1/evaluate performances of each model, 2/apply a QSAR strategy on the NIAS molecular space and address data-gaps.

New approach for hair keratin characterization: Use of the confocal Raman spectroscopy to assess the effect of thermal stress on human hair fibre.

Objective: The objective of our research was to investigate the heat-protecting effect of a product ex vivo and in vivo on human hair fibres.

Methods: A preparatory study was carried out in order to determine an optimal threshold of thermal stress. For this, the structure of cross-sections of the hair fibre was observed by optical microscopy.

Epidermal reconstructs: a new tool to study topical and systemic photoprotective molecules.

In this study, we compared the effects of sunscreens and antioxidants on reconstructed epidermis made with or without melanocytes 24 h after UVB, UVA or UVA+B irradiation. For this purpose, we studied sunburn cells and cyclobutane pyrimidine dimer formation, protein and lipid oxidation, catalase and superoxide dismutase activities and vitamin E levels. Topical sunscreens protected against direct cell death and thymine dimer formation whereas their protective effect against protein and lipid oxidation and antioxidant depletion was less marked partly due to the difficulty of spreading the cream.