August 2007 in “Microscopy and Microanalysis” Hair fibers break by cuticle cell slipping, shape changing, cuticle fraying, and surface cracking when stretched under specific conditions.
33 citations
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June 1995 in “International journal of legal medicine” Environmental factors can greatly reduce drug levels in hair.
3 citations
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June 2019 in “Journal of cosmetic dermatology” Lower pH straighteners change hair more but weaken it.
12 citations
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July 2015 in “British journal of dermatology/British journal of dermatology, Supplement” Curly hair breaks due to mechanical damage and environmental factors, not chemical makeup, and needs ongoing care to prevent breakage.
21 citations
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December 2011 in “Chungara” Mummy hair's chemical composition may not accurately show ancient people's health due to environmental contamination.