TLDR Hair relaxers and straighteners can be toxic to 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.
1 citations
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June 2021 in “Preprints.org” Hair relaxers and straighteners can be toxic to skin cells.
January 2011 in “Yearbook of Dermatology and Dermatologic Surgery” Hair relaxers are linked to reduced cystine levels and potential hair damage.
94 citations
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September 2008 in “Journal of the American Academy of Dermatology” Traction alopecia is more common in African women than girls, especially when traction is applied to chemically relaxed hair; avoiding such hairstyles may reduce the risk.
10 citations
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January 1994 Hair can be straightened using different chemicals, not just strong alkali.
2 citations
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January 2022 in “Anais brasileiros de dermatologia/Anais Brasileiros de Dermatologia” Chemical hair straighteners can cause scalp and hair damage, but long-term effects are unclear.
47 citations
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January 2017 in “RSC Advances” Keratin peptides can change hair shape gently without harsh chemicals.
20 citations
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July 1988 in “Clinics in dermatology” Thioglycolate lotions are the most popular method for permanent waving and hair straightening.
32 citations
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August 2015 in “Anais Brasileiros de Dermatologia” Black women's unique hair characteristics and styling practices can lead to specific scalp conditions, which require early diagnosis and appropriate treatment.
53 citations
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July 2016 in “Cosmetics” Future hair cosmetics will be safer and more effective.
