Registration Dossier

Administrative data

Endpoint:
skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
18 January 2012 to 09 July 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in accordance with current guideline and GLP compliant.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Deviations:
no
Principles of method if other than guideline:
N/A
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Naphthoxyethanol
- Lot/batch No.: E00173-186
- Physical state: solid
- Analytical purity: 98.5%
- Expiration date of the lot/batch: 31 July 2013

Results and discussion

In vivo

Irritant / corrosive response data:
Exposure to Naphthoxyethanol resulted in a mean EpiSkin viability of 91.77% ± 2.70% of the negative control value.

Any other information on results incl. tables

MTT Direct Reduction Test (Preliminary Assay)

 

The test was scored by visual assessment of the formation of purple-coloured formazan. The positive control eugenol reduced the MTT solution to purple-coloured formazan. The negative controlwater did not reduce MTT to formazan after 3 h incubation. The test item,Naphthoxyethanol, did not reduce MTT to formazan after 3 h incubation.

 

EpiSkin® Irritation Test

Percentage Viability of EpiSkin® Tissues After ca 42h Recovery Time

Treatment

Mean viability per tissue (%)

Mean viability per test item (%)

SD (%)

2-Naphthoxyethanol

94.54

91.77

2.70

89.16

91.60

Aqueous SDS Solution

(5%, w/v)

(Positive Control)

6.20

10.52

3.91

13.83

11.54

PBS Solution

(Negative Control)

95.36

100.00

4.87

99.58

105.07

The negative control results were similar for the three viable EpiSkin® units dosed with Dulbecco’s PBS. Exposure to Dulbecco’s PBS resulted in a mean EpiSkin® viability of 100.00% ±4.87%.

 

The positive control results were similar for the three viable EpiSkin® units dosed with aqueous SDS solution (5%, w/v). Exposure to aqueous SDS solution (5%, w/v) resulted in amean EpiSkin® viability of 10.52% ±3.91%.

 

The results were similar for the three viable EpiSkin® units dosed with Naphthoxyethanol.Exposure to Naphthoxyethanol resulted in a mean EpiSkin® viability of 91.77% ±2.70% ofthe negative control value.

 

The test item was considered to be irritant to skin in accordance with GHS category 2 if the tissue viability after exposure and post-treatment incubation was less than or equal (≤) to 50%.

Applicant's summary and conclusion

Interpretation of results:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: OECD GHS
Conclusions:
Naphthoxyethanol was demonstrated to be non-irritant when tested in the EpiSkin® in vitro irritation assay.
Executive summary:

Evaluation of skin irritation is part of the Human Health Hazard Assessment required for registration of a chemical. In this study, the irritation potential of Naphthoxyethanol was evaluated using the SkinEthic EpiSkin in vitro irritation assay. Prior to the conduct of the irritation assay, a preliminary test was conducted to assess the intrinsic ability of the test item to reduce methylthiazoldiphenyl-tetrazolium bromide (MTT) to formazan. Naphthoxyethanol did not reduce MTT to formazan. The dermal irritation potential was assessed by applying 10 mg ± 2 mg of the solid Naphthoxyethanol to the exposed surface of three EpiSkin reconstructed human epidermis (RhE) units for 15 min. Prior to applying the test item, the EpiSkin surface was pre-moistened with sterile, ultra-pure water (5 μL). The surface area of the EpiSkin was 0.38 cm2, therefore the application rate was ca 26.3 mg/cm2. After the 15 min exposure period, the test item was washed from the surface of the EpiSkin using Dulbecco’s phosphate-buffered saline (PBS). The EpiSkin was then incubated for a recovery period of ca 42 h in a humidified incubator, set to maintain temperature and CO2 levels of 37°C and 5%, respectively. Following incubation, the EpiSkin units were transferred to assay medium containing MTT (0.3 mg/mL) and returned to the incubator for 3 h. Biopsies of the EpiSkin membranes were removed, added to acidified isopropanol, and refrigerated for ca 69 h in order to extract the

formazan. The formazan production (cell viability) was assessed by measuring the optical density of the extracts at a wavelength of 550 nm. Three replicates of the positive control, aqueous sodium dodecyl sulphate (SDS) solution (5%, w/v) (10 μL), and the negative control, PBS (10 μL) were tested in parallel to demonstrate the efficacy of the assay. The viability of each individual EpiSkin tissue was calculated as a percentage of the mean negative control viability (defined as 100%). Exposure to Naphthoxyethanol resulted in a mean EpiSkin viability of 91.77% ± 2.70% of the negative control value. Exposure to the positive control, aqueous SDS solution (5%, w/v), resulted in a mean EpiSkin viability of 10.52% ± 3.91% of the negative control value. In conclusion, Naphthoxyethanol was demonstrated to be non-irritant when tested in the EpiSkin in vitro irritation assay.