Reaction mass of disodium metasilicate and sodium hydroxide

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

repeated dose toxicity: inhalation

Remarks:

other: Assessment

Type of information:

other: Expert Assessment

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Expert Assessment as opposed to experimental result

Data source

Reference

Reference Type:

other: Expert Assessment

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Principles of method if other than guideline:

Assessment

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of disodium metasilicate and sodium hydroxide

EC Number:

910-245-3

Molecular formula:

NaOH Na2SiO3

IUPAC Name:

Reaction mass of disodium metasilicate and sodium hydroxide

Results and discussion

Effect levels

Remarks on result:

not measured/tested

Remarks:

It has an aqueous pH of >13; the high pH makes testing by the inhalation route inappropriate for animal welfare reasons

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Assessment

Applicant's summary and conclusion

Executive summary:

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. It has an aqueous pH of >13; the high pH makes testing by the inhalation route inappropriate for animal welfare reasons. In addition, REACH Annex VIII requires testing by “the most appropriate route of exposure” where acute testing additional to the oral route is appropriate. As well as animal welfare considerations, testing by the inhalation route would be inappropriate as the severe irritancy affect would mask any systemic toxicity effects. An inhalation toxicity study has been conducted for silicic acid, potassium salt (215-199-1), which showed an LC₅₀ of >2.06 mg/L air. Thus, running an acute inhalation study would add nothing to the hazard assessment for this substance, and risk management measures are driven primarily by its corrosive nature due to the high pH. Determination of acute toxicity by the inhalation route is therefore considered inappropriate and unnecessary.

The above should be considered as an expert statement to waive the requirement for testing for acute toxicity by the inhalation route REACH Annex VIII for endpoint 8.6.1.