Cytotoxic Evaluation of Hair Relaxers and Straighteners Actives in Human-Derived Skin Cells

This study evaluated the cytotoxic effects of hair relaxers and straighteners, which typically have a pH above 11 and are linked to increased alopecia risk and skin irritation. With the EU ban on animal testing, the study used in vitro cell-based technologies and human-derived skin cells to assess toxicity. It found that relaxers containing thioglycolic acid, ammonium bisulphite, lithium hydroxide, and sodium hydroxide caused significant cellular toxicity, reducing cell index and ATP production, and increasing apoptosis in keratinocytes and fibroblasts. The study concluded that these in vitro methods could effectively replace animal testing for evaluating the safety of hair relaxers and cosmetics.