Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

Sodium Hydroxide: Source - the sodium hydroxide summary risk assessment report JRC EC 2008

Based on a negative human skin sensitisation study and the fact that no human cases of skin and respiratory sensitisation have been reported despite the long and widespread use of NaOH, the substance is not considered to be a skin and respiratory sensitiser.


Migrated from Short description of key information:
This substance is a multi-constituent substance consisting of sodium hydroxide (215-185-5, 1310-73-2) and disodium metasilicate (229-912-9, 6834-92-0). It is the by-product of a reaction between zircon (EC no 239-019-6) and sodium hydroxide; after hydrolysis, this substance is the water-soluble fraction. The substance in water has a pH of > 13 due to the presence of significant amounts of sodium hydroxide. The substance as produced would be highly corrosive to skin due to the alkali; testing would not be required to demonstrate this as the properties of sodium hydroxide are well-known. In vivo testing of the substance would be inappropriate on animal welfare grounds, and such testing for substances where the pH is >11 is prohibited. The substance is classified based on this as skin corrosion/irritation, category 1A (H314), i.e. corrosive. Disodium metasilicate (229-912-9) has been tested for skin sensitisation. This would not contribute at all to the corrosiveness due to the sodium hydroxide present in this substance. In view of the corrosive nature of this substance, its potential for sensitisation is essentially irrelevant.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

Sodium Hydroxide: Source - the sodium hydroxide summary risk assessment report JRC EC 2008

Based on a negative human skin sensitisation study and the fact that no human cases of skin and respiratory sensitisation have been reported despite the long and widespread use of NaOH, the substance is not considered to be a skin and respiratory sensitiser.


Migrated from Short description of key information:
This substance is a multi-constituent substance consisting of sodium hydroxide (215-185-5, 1310-73-2) and disodium metasilicate (229-912-9, 6834-92-0). It is the by-product of a reaction between zircon (EC no 239-019-6) and sodium hydroxide; after hydrolysis, this substance is the water-soluble fraction. The substance in water has a pH of >13, due to the presence of significant amounts of sodium hydroxide. The substance as produced would be highly corrosive to skin due to the alkali; testing would not be required to demonstrate this as the properties of sodium hydroxide are well-known. In vivo testing of the substance would be inappropriate on animal welfare grounds, and such testing for substances where the pH is >11 is prohibited. The substance is classified based on this as skin corrosion/irritation, category 1A (H314), i.e. corrosive. Disodium metasilicate (229-912-9) has been tested for skin sensitisation. This would not contribute at all to the corrosiveness due to the sodium hydroxide present in this substance. In view of the corrosive nature of this substance, its potential for sensitisation is essentially irrelevant.

Justification for classification or non-classification