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Ethyl Thioglycolate
AKA “Ethyl 2-mercaptoacetate, Ethyl mercaptoacetate, USAF EK-2070, Thioglykolsaeure-aethylester, NSC 8834, Ethyl .alpha.-mercaptoacetate, Acetic acid, ethyl ester”
Synthetic
Ingredient Facts
Ethyl thioglycolate
AKA: Ethyl 2-mercaptoacetate, Ethyl mercaptoacetate, USAF EK-2070, Thioglykolsaeure-aethylester, NSC 8834, Ethyl .alpha.-mercaptoacetate, Acetic acid, Ethyl ester
Synthetic · Depilatory · EWG: 4
Synthetic
Synthetic
Clean
A chemical that breaks down hair structure to relax waves or remove unwanted hair. Used in professional straightening and hair removal treatments.
Formula
C4H8O2S
Mol. Weight
120.17
CAS #
623-51-8
Form
Liquid
State
Colorless liquid with a stench; [Alfa Aesar MSDS]
See origin →
Functions
Depilatory
Hair Waving Or Straightening
Reducing
Moisturizing
Locks in moisture to keep skin soft and supple throughout the day
Strengthens Barrier
Changes hair texture
Removes unwanted hair
Chemical reduction
Traditional Use
Developed as a reducing agent in the 1940s-1950s. Became the standard active ingredient in chemical hair relaxers and permanent wave solutions due to its ability to break disulfide bonds in hair.
Skin Types
●all-skin-types
Best For
General
Melanin-Rich Skin
Suitable
Pregnancy & Breastfeeding Safe
Caution
EWG
4
CIR
Safe w/Qualifications
Pregnancy
Caution
CIR Safety Findings
Not a Sensitizer
medical-approval
all-shades-safe
Regulatory Status
USA✔ permitted
EU✔ permitted
JAPAN✔ permitted
CANADA✔ permitted
RIFM fragrance ingredient safety assessment, pentanedioic acid, 1,5-dimethyl ester, CAS Registry Number 1119-40-0.
Api AM, Belsito D, Botelho D, Browne D, Bruze M et al.
Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2018
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Safety Assessment of Tetrasodium Glutamate Diacetate and Beta-Alanine Diacetic Acid as Used in Cosmetics.
Burnett CL, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2025
→
Safety Assessment of Tetrasodium Glutamate Diacetate and Beta-Alanine Diacetic Acid as Used in Cosmetics.
Burnett CL, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2025
→
Sodium Dehydroacetate and Dehydroacetic Acid.
Cherian P, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2024
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Sodium Dehydroacetate and Dehydroacetic Acid.
Cherian P, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2024
→
Final Amended Report on the Safety Assessment of Ammonium Thioglycolate, Butyl Thioglycolate, Calcium Thioglycolate, Ethanolamine Thioglycolate, Ethyl Thioglycolate, Glyceryl Thioglycolate, Isooctyl T
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Final Report on the Safety Assessment of Ethyl Ester of PVM/MA Copolymer and Butyl Ester of PVM/MA Copolymer
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Final Report on the Safety Assessment of Sodium Dehydroacetate and Dehydroacetic Acid
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Safety Assessment of Tetrasodium Glutamate Diacetate and Beta-Alanine Diacetic Acid as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Sodium Dehydroacetate and Dehydroacetic Acid
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Acetic Acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Beta-Alanine Diacetic Acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
dehydroacetic acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Ethyl Ester of PVM/MA Copolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Ethyl Thioglycolate
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Methyl Thioglycolate
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Potassium Ethyl Ester of PVM/MA Copolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Shea Butter Ethyl Esters
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Silybum marianum ethyl ester
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Acetic acid and the skin: a review of vinegar in dermatology.
Elhage KG, St Claire K, Daveluy S
International journal of dermatology, 2022
→
Acetic acid and the skin: a review of vinegar in dermatology.
Elhage KG, St Claire K, Daveluy S
International journal of dermatology, 2022
→
Acetic Acid
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
dehydroacetic acid
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Ethyl Ester of PVM/MA Copolymer
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Shea Butter Ethyl Esters
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Potential application of novel liquid crystal nanoparticles of isostearyl glyceryl ether for transdermal delivery of 4-biphenyl acetic acid.
Fujii MY, Asakawa Y, Fukami T
International journal of pharmaceutics, 2020
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Preparation of (13)C-labeled ceramide by acetic acid bacteria and its incorporation in mice.
Fukami H, Tachimoto H, Kishi M, Kaga T, Waki H et al.
Journal of lipid research, 2010
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Detection of fatty acid ethyl esters in skin surface lipids as biomarkers of ethanol consumption in alcoholics, social drinkers, light drinkers, and t
González-Illán F, Ojeda-Torres G, Díaz-Vázquez LM, Rosario O
Journal of analytical toxicology, 2011
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3-Imidazol-4-ylacrylic acid and its ethyl ester
Health Canada
Health Canada Cosmetic Ingredient Hotlist
→
Trichloroacetic acid
Health Canada
Health Canada Cosmetic Ingredient Hotlist
→
Synthesis of mixed esters of ascorbic acid using methyl esters of palm and soybean oils.
Hsieh HJ, Chen JW, Giridhar R, Wu WT
Preparative biochemistry & biotechnology, 2005
→
Verified Feb 2026
Data: PubChem · CosIng · EWG · CIR