Silicic acid, lithium salt

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation / corrosion

Remarks:

other: EpiDerm (in vitro)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 - 27 Sep 2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study according to a draft guideline with acceptable restrictions (limited documentation).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD guideline for the testing of chemicals. Draft proposal for a new guideline. In vitro skin irritation: human skin model test, December, 2007

Deviations:

yes

Remarks:

- Interleukin-1 alpha was not determined

Principles of method if other than guideline:

The skin irritancy potenial of lithium silicate was tested by using the human skin model EpiDerm and measurement of cell viability by dehydrogenase conversion of MTT into a blue formazan salt.

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Mainz, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Silicic acid, lithium salt

EC Number:

235-730-0

EC Name:

Silicic acid, lithium salt

Cas Number:

12627-14-4

Molecular formula:

Li2O*2.8SiO2 - Li2O*6.3SiO2

IUPAC Name:

Silicic acid, lithium salt

Details on test material:

- Name of test material (as cited in study report): lithium silicate
- Physical state: white powder
- Analytical purity: > 99%
- Batch No.: 009061957
- Expiration date of the batch: 28.05.2010
- Storage condition of test material: at room temperature, 20 ± 5 °C
- Other: Molar Ratio SiO2/Li2O: 4.8 (information provided in the product information sheet for Lithium polysilicate by the data owner)

Test animals

Species:

other: in vitro test: human skin

Strain:

other: in vitro test: human skin

Details on test animals or test system and environmental conditions:

not applicable

Test system

Type of coverage:

other: in vitro test: human skin model test

Preparation of test site:

other: in vitro test: human skin model test

Vehicle:

other: DPBS buffer

Controls:

other: not applicable

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (weight): 25 mg of the neat test item were applied to each of triplicate tissues and wetted with 25 µL DPBS (Dulbecco's Phophate Buffered Saline) buffer.

VEHICLE
- Amount(s) applied (volume): 25 µL DPBS buffer

Duration of treatment / exposure:

not applicable: see "any other information on materials and methods"

Observation period:

not applicable: see "any other information on materials and methods"

Number of animals:

not applicable: see "any other information on materials and methods"

Details on study design:

not applicable: see "any other information on materials and methods"

Results and discussion

In vivo

Irritant / corrosive response data:

Under the experimental conditions, the test item is considered to have no skin irritation potential.

Any other information on results incl. tables

After treatment with the negative control the absorbance values were well within the required acceptability criterion thus showing the quality of the tissues. The positive control induced a decrease in the relative absorbance as compared to the negative control to 15.8% thus ensuring the validity of the test system. After tissue incubation with lithium silicate, the relative absorbance values were increased to 111.5%. This value is well above the threshold for irritancy of 50%. Therefore, the test item is considered to have no skin irritation potential.Results see table 1.

Table 1:

Dose group	Absorbance 570 nm, tissue 1*	Absorbance 570 nm, tissue 2*	Absorbance 570 nm, tissue 3*	Mean absorbance of 3 tissues	Mean formazan production [%]
Negative control	1.454	1.568	1.633	1.562	100%
Positive control	0.253	0.249	0.240	0.247	15.8%
Test item	1.629	1.752	1.844	1.742	111.5%

*Mean of two measurements after blank correction

** relative absorbance [rounded values]: (100 x (absorbance test item)) / (absorbance negative control)

Applicant's summary and conclusion

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

CLP: not classified
DSD: not classified