2-(2-naphthyloxy)ethanol

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01 to 16 February 2012

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River, Margate
- Age at study initiation: Between 8 and 10 weeks old
- Weight at study initiation: 16.6 to 21.0 g
- Housing: In groups of 2 or 3
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 8 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21°C to 22°C
- Humidity (%): 48% to 70%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: To: 01 to 13 February 2012

Vehicle:

other: maize oil

Concentration:

0%, 2.5%, 10% and 50%

No. of animals per dose:

6 at 0% and 4 at each of 2.5%, 10% and 50%

Details on study design:

RANGE FINDING TESTS:
- Irritation and toxicity

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay: dermal application
- Criteria used to consider a positive response: Stimulation Indices greater than or equal to 3 in groups treated at either 2.5%, 10% or 50%

TREATMENT PREPARATION AND ADMINISTRATION: No preparation. Dermal administration to dorsum of the ears by micropipette

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

Dixon’s Q-test for the detection of a single outlier was performed on disintegrations per minute values

Positive control results:

Stimulation index = 8.09

Parameter:

SI

Value:

1

Test group / Remarks:

Control

Parameter:

SI

Value:

1.25

Test group / Remarks:

Group 2 (2.5%)

Parameter:

SI

Value:

1.15

Test group / Remarks:

Group 3 (10%)

Parameter:

SI

Value:

1.59

Test group / Remarks:

Group 4 (50%)

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Control group = 1533. Group 2 (2.5%) = 1916. Group 3 (10%) = 1766. Group 4 (50%) = 2440.

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the conditions of the study, since treatment with 2-(2-naphthoxy)ethanol at concentrations of up to 50% did not achieve a stimulation index of =3, it was considered that the test item does not have the potential to cause skin sensitisation.
This study is considered to be relevant, reliable and adequate for risk assessment and for classification purposes.

Executive summary:

The objective of this study was to determine the delayed contact hypersensitivity potential of 2-(2-naphthoxy)ethanol. 

The study was performed using female CBA/Ca mice. A preliminary test was conducted by administering a 50% concentration of test item to two mice. Each mouse received an open application of 25 µL of test formulation onto the dorsum of each ear.

As a result of the findings from the preliminary test, formulation concentrations were selected for the main study. The study design for the main study was as follows:

Text Table1
Experimental Design

Group Number	Treatment	Formulation Concentration (%)	Animal Numbers
1	Vehicle Control	0	1 to 6
2	2-(2-naphthoxy)ethanol	2.5	7 to 10
3	2-(2-naphthoxy)ethanol	10	11 to 14
4	2-(2-naphthoxy)ethanol	50	15 to 18
5	Hexylcinnamicaldehyde (HCA)	50	49 to 52

 

The selected vehicle was corn oil and the vehicle control group received only this. Each mouse received an open application of 25 µL of the appropriate formulation onto the dorsum of each ear for 3 consecutive days. Three days after the final application each animal received an intravenous injection of [methyl-³H] thymidine into the lateral tail vein. Approximately 5 h later the draining auricular lymph nodes were collected in order that incorporation of tritiated thymidine could be assessed by scintillation counting.

The stimulation indices (SI) for groups of mice that received 2-(2-naphthoxy)ethanol at concentrations of 2.5%, 10% or 50%, when compared with controls, were 1.25, 1.15 and 1.59, respectively. The group treated with HCA, a chemical known to induce skin sensitisation, recorded a stimulation index of 8.09. This is considered to demonstrate competent performance of the test procedures.

Under the conditions of the study, since treatment with 2-(2-naphthoxy)ethanol at concentrations of up to 50% did not achieve a stimulation index of =3, it was considered that the test item does not have the potential to cause skin sensitisation.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The substance was tested for skin sensitisation potential in the mouse local lymph node assay.The Stimulation Index did not exceed 3 in any treatment group; therefore, the test material was considered to be a non-sensitiser under the conditions of the test.

Migrated from Short description of key information:
The substance is not a skin sensitiser based on the results of a Local Lymph Node Assay.

Justification for selection of skin sensitisation endpoint:
Study conducted in accordance with OECD guidelines and GLP. Klimisch score 1.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the negative result in the Local Lymph Node Assay, no classification for skin sensitisation is required.

The respiratory sensitisation potential of the substance has not been tested experimentally, but based on the lack of dermal sensitisation potential, it is concluded that based on current knowledge no classification for respiratory sensitisation is required.