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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin corrosion: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
18 April - 04 September 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study was conducted in accordance with international guidelines and in accordance with GLP. All guideline validity criteria were met.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)
Version / remarks:
29 July 2009
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))
Version / remarks:
Council Regulation (EC) No 440/2008, 30 May 2008
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
impurity
Type:
impurity
Type:
impurity
Type:
impurity
Type:
impurity
Type:
impurity
Test material form:
solid
Details on test material:
Storage: ambient (5 °C – 30 °C), dark, dry
Specific details on test material used for the study:
RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: n/a
- Specific activity: n/a
- Locations of the label: n/a
- Expiration date of radiochemical substance: n/a

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: assumed stable
- Solubility and stability of the test substance in the solvent/vehicle: test item applied as a paste using 50 µL water per 25 mg of test item powder.
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: no

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: test item applied as a paste using 50 µL water per 25 mg of test item powder.
- Preliminary purification step (if any): no
- Final dilution of a dissolved solid, stock liquid or gel: 25 mg of test item applied to skin using 50 µL of water (as a paste)
- Final preparation of a solid: n/a

FORM AS APPLIED IN THE TEST (if different from that of starting material) : test item applied as a paste using 50 µL water per 25 mg of test item powder.

TYPE OF BIOCIDE/PESTICIDE FORMULATION (if applicable) n/a

OTHER SPECIFICS: n/a

In vitro test system

Test system:
human skin model
Source species:
human
Cell type:
non-transformed keratinocytes
Cell source:
other: normal (non-cancerous), human-derived epidermal keratinocytes (NHEK) were cultured to form a multilayered, highly differentiated model of the human epidermis. Model was supplied by MatTek In Vitro Life Sciences, Bratislava, Slovak Republic
Details on test system:
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDermTM Reconstructed Human Epidermis
- EpiDerm RHE kit lot #: 25806
- Production date: Not reported
- Shipping date: Not reported
- Delivery date: Not reported
- Date of initiation of testing: 20 April 2017

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 ± 1 ºC
- Temperature of post-treatment incubation (if applicable): 37 ± 1 ºC

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: Rinsed with PBS ("20 times"), volume not reported.
- Observable damage in the tissue due to washing: Not reported, assume no.
- Modifications to validated SOP: No

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1 mg/mL
- Incubation time: 3 hours
- Spectrophotometer: Yes, details not reported
- Wavelength: 570 nm
- Filter: No / not reported
- Filter bandwidth: No / not reported
- Linear OD range of spectrophotometer: Not reported

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: Acceptable
- Barrier function: Not reported
- Morphology: Not reported
- Contamination: Not reported
- Reproducibility: COV of mean replicated was <30 %.

NUMBER OF REPLICATE TISSUES: 2

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
- Freeze killed tissues
- Procedure used to prepare the killed tissues (if applicable): Not applicable - substance was not a MTT reducer.
- No. of replicates : Not applicable

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 2

PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
- The test substance is considered to be corrosive to skin if the viability after 3 minutes exposure is less than 50%, or if the viability after 3 minutes exposure is greater than or equal to 50 % and the viability after 1 hour exposure is less than 15%.
- The test substance is considered to be non-corrosive to skin if the viability after 3 minutes exposure is greater than or equal to 50% and the viability after 1 hour exposure is greater than or equal to 15%.
- Justification for the selection of the cut-off point(s) if different than recommended in TG 431 and 439: N/a
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 25 mg
- Concentration (if solution): Powder applied using 50 µL of distilled water (as a paste)

VEHICLE
- Amount(s) applied (volume or weight with unit): 50 µL
- Concentration (if solution): Not applicable
- Lot/batch no. (if required): Lot # RNBF7110
- Purity: Not reported (assume 100 % for distilled water)

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): Not applicable

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): 8 N
Duration of treatment / exposure:
3 minutes and 60 minutes
Duration of post-treatment incubation (if applicable):
Incubated in MTT medium for 3 hours and followed by an overnight extraction in isopropanol.
Number of replicates:
2 for each treatment

Test animals

Species:
other: n/a
Strain:
other: n/a
Details on test animals and environmental conditions:
n/a

Test system

Type of coverage:
other: n/a
Preparation of test site:
other: n/a
Vehicle:
other: n/a
Amount / concentration applied:
n/a
Duration of treatment / exposure:
n/a
Observation period:
n/a
Number of animals:
n/a
Details on study design:
n/a

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
3 min exposure
Value:
87.9
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of irritation
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
60 min exposure
Value:
4.2
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of irritation
Other effects / acceptance of results:
- OTHER EFFECTS:
- Visible damage on test system: No
- Direct-MTT reduction: No
- Colour interference with MTT: No

DEMONSTRATION OF TECHNICAL PROFICIENCY: Yes

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: Yes
- Acceptance criteria met for positive control: Yes
- Acceptance criteria met for variability between replicate measurements: Yes
- Range of historical values if different from the ones specified in the test guideline: N/A

Any other information on results incl. tables

Table 2:       Mean OD570Values and Viabilities for the Negative Control Item, Positive Control Item and Test Item

Tissue

Exposure Period

MeanOD570of individual tissues

Mean OD570of duplicate tissues

Standard Deviation

Coefficient of Variation

(%)***

Relative Mean Viability (%)

Negative Control

3 Minutes

1.646

1.663*

0.025

1.5

100

1.681

60 Minutes

1.680

1.695*

0.020

1.2

1.709

Positive Control

3 Minutes

0.144

0.148

0.005

3.1

8.9

0.151

60 Minutes

0.075

0.097

0.032

32.8

5.7**

0.120

Test Item

3 Minutes

1.482

1.462

0.029

2.0

87.9

1.442

60 Minutes

0.077

0.071

0.020

1.2

4.2

0.066

* mean OD5700.7 – 2.8

** mean relative tissue viability of the 60 min positive control < 15 %

*** COV (in the range of 20 – 100 % viability) between two tissues treated identically is ≤ 30 %

Applicant's summary and conclusion

Interpretation of results:
other: A combination of optional Sub-categories 1B-and-1C
Conclusions:
In this study under the given conditions the test item showed corrosive effects. The mean relative tissue viability (% negative control) was reduced below 15% after 60 min treatment but not below 50% after 3 min treatment. Sodium Octane-1-sulphonate is therefore classified as “corrosive“ in accordance with UN GHS sub-category 1B.
Executive summary:

OECD 431 (2017) - The skin corrosivity potential of sodium octane-1-sulphonate was assessed using an EpiDerm Reconstructed Human Epidermis (RHE) Model Kit in accordance with OECD guidance 431 and GLP.

Duplicate tissues were treated with the test item for exposure periods of 3 and 60 mins. At the end of the exposure period the test item was rinsed from each tissue before being loaded with MTT. After MTT loading each tissue was placed in 2 mL isopropanol for MTT extraction. After extraction, each tissue was pierced and the extraction solution aliquoted for absorbance measurements. Absorbency at 570 nm of each well was measured using a spectrophotometer.

Mean viability of tissues exposed to the test substance after 3 and 60 minutes were 87.9 % and 4.2 %, respectively. The quality criteria required for acceptance of the results was met.

Under the conditions of this study the test substance is considered to be corrosive to the skin in accordance with a combination of optional UN GHS sub-categories 1B and 1C; however for the purposes of conservative classification the substances is designated as corrossive: sub-category 1B.