Benzeneacetic acid, 2-(6-carboxy-2,3-dimethylphenoxy)-

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11-24 November 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to EC and OECD guidelines and according to GLP principles

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

2-[2-(carboxymethyl)phenoxy]-3,4-dimethylbenzoic acid

EC Number:

601-485-7

Cas Number:

117570-93-1

Molecular formula:

C17 H16 O5

IUPAC Name:

2-[2-(carboxymethyl)phenoxy]-3,4-dimethylbenzoic acid

Constituent 2

Reference substance name:

2-(6-carboxy-2,3-dimethylphenoxy)-benzeneacetic acid

IUPAC Name:

2-(6-carboxy-2,3-dimethylphenoxy)-benzeneacetic acid

Details on test material:

- Name of test material (as cited in study report): ASA404 C7
- Substance type: off-white powder
- Physical state: solid
- Analytical purity:99.9%
- Purity test date: 18 September 2008
- Lot/batch No.: 072301
- Expiration date of the lot/batch:18 March 2009
- Stability under test conditions: not indicated
- Storage condition of test material: stable

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River France, L'Arbresle Cedex, France
- Age at study initiation: 10-11 weeks
- Weight at study initiation: 21-25 g
- Housing: Individual housing in Macrolon cages (MI type; height 12.5 cm) containing sterilized sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France). During the acclimatization period, the animals were group housed in Macrolon cages (MIII type; height 18 cm).
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17.7-23.6
- Humidity (%): 38-74
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 11 November 2008 To: 24 November 2008

Study design: in vivo (LLNA)

Vehicle:

dimethyl sulphoxide

Concentration:

0, 10, 25 and 50% test substance concentration

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: Formulations (w/w) were prepared within 4 hours prior to dosing and were homogenised to visually acceptable levels.
- Irritation: slight erythema at 50% test substance concentration

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response: DPM values are presented for each animal and for each dose group. A Stimulation Index (SI) is calculated for each group. The SI is the ratio of the DPM/group compared to DPM/vehicle control group.
If the results indicate a SI >= 3, the test substance may be regarded as a skin sensitizer, based on the test guideline and recommendations done by ICCVAM.

TREATMENT PREPARATION AND ADMINISTRATION: the dorsal surface of both ears was epidermally treated (25 μL/ear) with the test item concentration, approximately the same time each day. The concentrations were mixed thoroughly using a vortex mixer immediately prior to dosing. The control animals were treated as described for the experimental animals, except that, instead of the test substance, the vehicle was administered.Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed.

Positive control substance(s):

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

Statistics:

not performed

Results and discussion

Positive control results:

The six monthly reliability check with Hexylcinnamaldehyde, indicates that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: The SI values calculated for the substance concentrations 10, 25 and 50% were 0.9, 1.2 and 1.6 respectively.

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Mean DPM/animal values for the experimental groups treated with test substance concentrations 10, 25 and 50% were 444, 610 and 814 respectively.The mean DPM/animal value for the vehicle control group was 499.

Any other information on results incl. tables

The irritation of the ears as shown by the animals, was considered not to have a toxicologically significant effect on the activity of the nodes.

The majority of nodes were considered normal in size, except for one or two nodes of two animals at 50%. No macroscopic abnormalities of the surrounding area were noted.

Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. The slight body weight loss, noted in some animals, was considered not toxicologically significant.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

Since there was no indication that the test substance elicit an SI >= 3 when tested up to 50%, ASA404 C7 was considered not to be a skin sensitizer.
Based on these results:
- according to the recommendations made in the test guidelines, ASA404 C7 would not be regarded as skin sensitizer.
- according to the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) of the United Nations (2007), ASA404 C7 does not have to be classified as skin sensitizer (Category 1).
- according to the EC criteria for classification and labeling requirements for dangerous substances and preparations (Council Directive 67/548/EEC), ASA404 C7 does not have to be classified and has no obligatory labeling requirement for sensitization by skin contact.