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THIOGLYCERIN.

Avoid CAS 96-27-5 / DEPILATORY, HAIR WAVING OR STRAIGHTENING, KERATOLYTIC, REDUCING

Thioglycerin is an organic compound recognized for its role as a reducing agent, particularly in altering hair structure. It also presents potential moisturizing benefits as a humectant and demonstrates antioxidant activity, contributing to overall formulation stability.

Reducing Agent Humectant Antioxidant Penetration Enhancer Keratolytic Product Stabilizer Depilatory Hair Waving/Straightening

Science

On the skin, Thioglycerin functions as a humectant, attracting environmental moisture to enhance hydration and improve texture. It also acts as an antioxidant, neutralizing free radicals that can contribute to skin aging. Furthermore, it serves as a penetration enhancer, potentially optimizing the delivery of other active ingredients. Its primary mechanism, involving the alteration of disulfide bonds within keratin, is most pronounced in hair applications for straightening or waving, while also stabilizing formulations by preventing ingredient separation and oxidation.


Research

Low confidence
Effective range 0.02–1%
Optimal

N/A

Key findings

  1. 01 Recommended for hair treatment and styling products, such as those designed for straightening or enhancing curls.
  2. 02 Utilized as a 1:5000 solution to promote wound healing in veterinary applications.

Transparency

Not commonly dusted

The Formula

Solubility
Both
Optimal pH 3.5 – 7
0 7 14

Stability

Thioglycerin is sensitive to air and light, which can lead to discoloration. Aqueous solutions and moist solids may slowly release hydrogen sulfide gas. While generally stable under standard conditions, moisture and temperatures exceeding 80°C must be avoided. For long-term preservation, stock solutions should be stored under nitrogen at -80°C for up to 6 months or -20°C for up to 1 month, strictly avoiding repeated freeze-thaw cycles. Heat and/or sonication can aid dissolution if precipitation or phase separation occurs during preparation.

Conflicts

  • Bases
  • Oxidizing agents
  • Reducing agents
  • Alkali metals
  • Strong acids
  • Copper
  • Brass

Safety

CIR Status
Not reviewed
Sensitization risk High

Thioglycerin carries significant hazard classifications, including being harmful if swallowed, toxic in contact with skin, causing skin irritation, potentially triggering allergic skin reactions, causing serious eye irritation, and being toxic if inhaled. There is a notable risk for sensitization and allergic dermatitis, which can manifest as rash, itching, hives, or swelling. Chronic exposure to mercaptans, the chemical class to which Thioglycerin belongs, may result in damage to the lungs, kidneys, and liver. Although one source indicates no carcinogenic identification by major agencies, another lists it as a carcinogen on the US - Maine Chemicals of High Concern List, indicating conflicting regulatory evaluations. A specific CIR or SCCS safety assessment for Thioglycerin (CAS 96-27-5) is not available; reports frequently pertain to Thioglycolic Acid (TGA), a distinct ingredient.


Your Skin

No Normal
No Dry
No Oily
No Sensitive
Irritancy High
Comedogenicity Unknown

Our Assessment

Avoid

Given the significant risks of irritation, sensitization, and systemic toxicity, along with conflicting carcinogen data and a lack of dedicated skincare safety assessments, Thioglycerin is not recommended for precision skincare formulations.


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