Safety Assessment of Inorganic Hydroxides as Used in Cosmetics

Abstract

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of inorganic hydroxides, which function in cosmetics primarily as pH adjusters. Representatives from the cosmetic industry have indicated these ingredients are used in depilating and hair waving/straightening formulations to raise pH values. The Panel considered relevant data related to these ingredients. The Panel concluded that these inorganic hydroxides are safe in hair straighteners and depilatories under conditions of recommended use; users should minimize skin contact. These ingredients are safe for all other present practices of use and concentration described in this safety assessment when formulated to be nonirritating.

Chemicals of concern in select packaged hair relaxers available on the Kenyan market: an examination of ingredient labels and measurement of pH

“…The CSC Red List classifies sodium hydroxide as both a Tier 2 and Tier 3 CoC, labeling it as an emerging CoC and a potential skin and eye irritant ( 32 ). However, the Expert Panel for Cosmetic Ingredient Safety has concluded that hydroxides, including sodium hydroxide, are safe in hair straighteners when applied under manufacturer recommended conditions with minimal skin contact ( 57 ).…”

Chemicals of concern in select packaged hair relaxers available on the Kenyan market: an examination of ingredient labels and measurement of pH

“…The CSC Red List classifies sodium hydroxide as both a Tier 2 and Tier 3 CoC, labeling it as an emerging CoC and a potential skin and eye irritant ( 32 ). However, the Expert Panel for Cosmetic Ingredient Safety has concluded that hydroxides, including sodium hydroxide, are safe in hair straighteners when applied under manufacturer recommended conditions with minimal skin contact ( 57 ).…”

Decoding Cosmetic Complexities: A Comprehensive Guide to Matrix Composition and Pretreatment Technology

“…The distinct acid–base properties of certain ingredients necessitate the use of pH adjusters to maintain the pH within this desired range [ 38 , 39 ]. Common pH adjusters include sodium hydroxide (NaOH), potassium hydroxide (KOH), triethanolamine, citric acid, sodium citrate, succinic acid, disodium succinate, and potassium phosphates (compounds 25 – 30 in Figure 4 ) [ 40 , 41 ]. Certain components, such as the high-molecular-weight thickener carbopol, require specific pH conditions to function optimally.…”

Safety Assessment of Zinc Salts as Used in Cosmetics

“…6,7 For complete and detailed information, please refer to the original documents, which are available on the Cosmetic Ingredient Review (CIR) website (https://www.cir-safety.org/ ingredients). Some of the constituent acids or salts, related to the zinc salt ingredients in this report, have been reviewed previously by the Panel; a summary of safety conclusions for those ingredients [2][3][4][5][8][9][10][11][12][13][14][15][16][17][18] is included in this report (Table 2). Those original reports are also available on the CIR website.…”

Chemicals of concern in select packaged hair relaxers available on the Kenyan market: an examination of ingredient labels and measurement of pH

“…The CSC Red List classifies sodium hydroxide as both a Tier 2 and Tier 3 CoC, labeling it as an emerging CoC and a potential skin and eye irritant ( 32 ). However, the Expert Panel for Cosmetic Ingredient Safety has concluded that hydroxides, including sodium hydroxide, are safe in hair straighteners when applied under manufacturer recommended conditions with minimal skin contact ( 57 ).…”

Decoding Cosmetic Complexities: A Comprehensive Guide to Matrix Composition and Pretreatment Technology

“…The distinct acid–base properties of certain ingredients necessitate the use of pH adjusters to maintain the pH within this desired range [ 38 , 39 ]. Common pH adjusters include sodium hydroxide (NaOH), potassium hydroxide (KOH), triethanolamine, citric acid, sodium citrate, succinic acid, disodium succinate, and potassium phosphates (compounds 25 – 30 in Figure 4 ) [ 40 , 41 ]. Certain components, such as the high-molecular-weight thickener carbopol, require specific pH conditions to function optimally.…”

Safety Assessment of Zinc Salts as Used in Cosmetics

“…6,7 For complete and detailed information, please refer to the original documents, which are available on the Cosmetic Ingredient Review (CIR) website (https://www.cir-safety.org/ ingredients). Some of the constituent acids or salts, related to the zinc salt ingredients in this report, have been reviewed previously by the Panel; a summary of safety conclusions for those ingredients [2][3][4][5][8][9][10][11][12][13][14][15][16][17][18] is included in this report (Table 2). Those original reports are also available on the CIR website.…”

Chemicals of concern in select packaged hair relaxers available on the Kenyan market: an examination of ingredient labels and measurement of pH

“…The CSC Red List classifies sodium hydroxide as both a Tier 2 and Tier 3 CoC, labeling it as an emerging CoC and a potential skin and eye irritant ( 32 ). However, the Expert Panel for Cosmetic Ingredient Safety has concluded that hydroxides, including sodium hydroxide, are safe in hair straighteners when applied under manufacturer recommended conditions with minimal skin contact ( 57 ).…”

Decoding Cosmetic Complexities: A Comprehensive Guide to Matrix Composition and Pretreatment Technology

“…The distinct acid–base properties of certain ingredients necessitate the use of pH adjusters to maintain the pH within this desired range [ 38 , 39 ]. Common pH adjusters include sodium hydroxide (NaOH), potassium hydroxide (KOH), triethanolamine, citric acid, sodium citrate, succinic acid, disodium succinate, and potassium phosphates (compounds 25 – 30 in Figure 4 ) [ 40 , 41 ]. Certain components, such as the high-molecular-weight thickener carbopol, require specific pH conditions to function optimally.…”

Safety Assessment of Zinc Salts as Used in Cosmetics

“…6,7 For complete and detailed information, please refer to the original documents, which are available on the Cosmetic Ingredient Review (CIR) website (https://www.cir-safety.org/ ingredients). Some of the constituent acids or salts, related to the zinc salt ingredients in this report, have been reviewed previously by the Panel; a summary of safety conclusions for those ingredients [2][3][4][5][8][9][10][11][12][13][14][15][16][17][18] is included in this report (Table 2). Those original reports are also available on the CIR website.…”