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Skin irritation / corrosion

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Administrative data

Endpoint:
skin irritation / corrosion
Remarks:
in vitro
Type of information:
experimental study
Adequacy of study:
key study
Study period:
13 Apr 2010 - 16 Apr 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))
Principles of method if other than guideline:
Skin corrosion ability was tested on a human three dimensional epidermal model (EpiDerm (EPI-200)).
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Silica-Zirkonia Filler
- Physical state: White powder
- Analytical purity of components: 72.4% silicon dioxide (CAS No. 7631-86-9) and 26.0% zirconium dioxide (CAS No. 1314-23-4) and a not stated percentage of disodium oxide (CAS No. 1313-59-3)
- Storage: at room temperature in the dark
- Batch: IT-253
- Stability: stable under storage conditions
- Expiry date: 20 Nov 2010
- not soluble in water

Test animals

Species:
human
Strain:
other: not applicable

Test system

Type of coverage:
other: not applicable, in vitro test
Preparation of test site:
other: moistened with water
Vehicle:
water
Controls:
other: not applicable, in vitro experiment
Amount / concentration applied:
Skin tissue was moistened with 25 µL of Milli-Q water.
25 mg test material was applied directly on top of the skin tissue and spread to match the size of the tissue.
Duration of treatment / exposure:
3 minutes and 1 hour
Observation period:
After exposure cytotoxicity was immediately determined by MTT assay. (Cytotoxicity was expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) at the end of the treatment.)
Number of animals:
not applicable, in vitro experiment
Details on study design:
TEST MODEL
EpiDerm Skin Model (EPI-200, Lot no.: 12971 kit K), surface 0.6 cm².
The model consisted of normal, human-derived epidermal keratinocytes which have been cultured to form a multilayered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EpiDerm tissues were cultured on polycarbonate membranes of 10 mm cell culture inserts placed on the surface of cell culture medium.
Source: MatTek Corporation, Ashland MA, U.S.A.

The test was performed on a total of 4 tissues per test substance together with negative and positive controls.
Negative control: Milli-Q water (Millipore Corp., Bedford, Mass., USA)
Positive control: 8.0 N Potassium hydroxide solution (KOH; Merck, Darmstadt, Germany)

Two tissues were used for a 3-minute exposure and two for a 1-hour exposure. After exposure, the tissues were washed with phosphate buffered saline (PBS) to remove residual test substance.

Cell viability was measured immediately after exposure by replacing the cell culture medium (DMEM) with MTT-medium (1 mg/mL) and incubation for 3 hours. After incubation the tissues were washed with PBS and formazan was extracted with 2 mL isopropanol. The amount of formazan was determined spectrophotometrically at 540 nm in triplicate with the Multiskan Spectrum (Thermo Labsystems). Cell viability was calculated for each tissue as percentage of the mean of the negative control tissues.

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
other: mean tissue viability
Value:
ca. 95
Remarks on result:
other:
Remarks:
The relative mean tissue viability obtained after the 3-minute with the test substance compared to the negative control tissues was 95%. (migrated information)
Irritation / corrosion parameter:
other: other: mean tissue viability
Value:
ca. 101
Remarks on result:
other:
Remarks:
The relative mean tissue viability obtained after the 1-hour treatments with the test substance compared to the negative control tissues was 101%. (migrated information)

In vivo

Irritant / corrosive response data:
The relative mean tissue viability obtained after the 3-minute and 1-hour treatments with the test substance compared to the negative control tissues was 95% and 101%, respectively. Because the mean relative tissue viability was not below 50% after 3 minutes treatment and not below 15% after 1 hour treatment, the test material was considered to be not corrosive.

Any other information on results incl. tables

No direct MTT reduction was found in the pretesting of the test material.

The absolute mean OD 540 (optical density at 540 nm) of the negative control and positive control tissues was within the laboratory historical control data range (collected in 44 observations in the period of January 2007 - December 2009).

Table 1: Mean absorption (OD540) in the in vitro skin corrosion test

 

3-minute application

1-hour application

 

A

B

Mean

A

B

Mean

Negative control (water)

1.711

1.634

1.673

1.718

1.748

1.733

Test material

1.618

1.564

1.591

1.763

1.754

1.758

Positive control (8.0 N KOH)

0.107

0.111

0.109

0.101

0.100

0.101

Duplicate exposures are indicated by A and B.

OD540= Optical density at 540 nm.

 

Table 2: Mean tissue viability in the in vitro skin corrosion test

 

3-minute application (percentage of control)

1-hour application

(percentage of control)

Negative control (water)

100

100

Test material

95

101

Positive control (8.0 N KOH)

7

6

 

Applicant's summary and conclusion

Interpretation of results:
other: not corrosive
Remarks:
Criteria used for interpretation of results: EU