Sodium hydrogen-5-sulphoisophthalate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September 25, 2013 - October 21, 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(2010)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(2008)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

(2003)

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Sodium hydrogen-5-sulphoisophthalate

EC Number:

228-845-2

EC Name:

Sodium hydrogen-5-sulphoisophthalate

Cas Number:

6362-79-4

Molecular formula:

C8H6O7S.Na

IUPAC Name:

Sodium 3,5-dicarboxybenzenesulfonate

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): 5-(Sodiosulfo)isophthalic Acid
- Description: White powder
- Expiration date of the batch: 24 February 2015
- Storage condition of test material: At room temperature in the dark
- pH: 2.3 (1% in water)

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/J

Sex:

female

Details on test animals and environmental conditions:

- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: Young adult female animals (approx. 11 weeks old)
- Weight at study initiation: Body weight variation was within +/- 20% of the sex mean (21-25 g)
- Housing: Animals were group housed in labeled makrolon cages.
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany).
- Water: Free access to tap water.
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 – 24
- Humidity (%): 40 - 70
- Air changes (per hr): approx 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: September 25, 2013 - October 21, 2013

Study design: in vivo (LLNA)

Vehicle:

propylene glycol

Concentration:

0, 10, 25, 50%

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Two test substance concentrations were tested; a 50% and 25% concentration.
- Two young adult animals per concentration were selected (in the range of 8 to14 weeks old).
- Each animal was treated with one concentration on three consecutive days.
- Ear thickness measurements were conducted using a digital thickness gauge prior to dosing on Days 1 and 3, and on Day 6.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- 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.

ANIMAL ASSIGNMENT
Three groups of five animals were treated with one test substance concentration per group. One group of five animals was treated with vehicle.

TREATMENT PREPARATION AND ADMINISTRATION:
- Test substance preparation: The test substance formulations (w/w) were prepared within 4 hours prior to each dosing. No adjustment was made for specific gravity of the vehicle. Homogeneity was obtained to visually acceptable levels.
- Rationale for vehicle: The vehicle was selected on the basis of maximizing the solubility using the test substance data provided by the sponsor and trial formulation results performed at WIL Research Europe.

Induction - Days 1, 2 and 3; Excision of nodes - Day 6; Tissue processing for radioacitivity - Day 6; Radioactivity measurements - Day 7; Performed according to test guidelines.

Observations:
Mortality/Viability: Twice daily.
Body weights: On Day 1 (pre-dose) and Day 6 (prior to necropsy).
Clinical signs: Once daily on Days 1-6 (on Days 1-3 between 3 and 4 hours after dosing).
Irritation: Once daily on Days 1-6 (on Days 1 - 3 within 1 hour after dosing) according to the numerical scoring system of OECD 404. Furthermore, a description of all other (local) effects was recorded according to guidelines.

Necropsy: No necropsy was performed

Positive control substance(s):

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

Results and discussion

Positive control results:

- In the latest performed reliability check, in April 2013, the SI values calculated for the substance concentrations 5, 10 and 25% were 1.2, 1.6 and 7.7 respectively. An EC3 value of 13.4% was calculated using linear interpolation.
- The six-month reliability check with Alpha-hexylcinnamicaldehyde (HCA) therefore indicates that the Local Lymph Node Assay as performed at WIL Research Europe is an appropriate model for testing for contact hypersensitivity. The results of the 6 monthly HCA reliability checks of the recent years were 16.0, 11.9, 16.9, 14.4, 16.5, 14.5 and 16.5%.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

2.8

Test group / Remarks:

50%

Results 2

Parameter:

SI

Value:

1.6

Test group / Remarks:

25%

Results 3

Parameter:

SI

Value:

1.3

Test group / Remarks:

10%

Cellular proliferation data / Observations:

Mean DPM/animal values for the experimental groups treated with test substance concentrations 10, 25 and 50% were 219, 254 and 457 DPM respectively. The mean DPM/animal value for the vehicle control group was 163 DPM. The SI values calculated for the substance concentrations 10, 25 and 50% were 1.3, 1.6 and 2.8 respectively.

Any other information on results incl. tables

Results Pre-screen test:

- No irritation and no signs of systemic toxicity were observed in any of the animals

- White test substance remnants were present on the dorsal surface of the ears of all animals between Days 1 and 3, this did not hamper scoring of the skin reactions.

- Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values (≤7%)

- Based on these results, the highest test substance concentration selected for the main study was a 50% concentration.

Other results - main study:

- No irritation of the ears was observed in any of the animals

- Test substance remnants were present on the dorsal surface of the ears of all animals treated at 25% between Days 1 and 2 and two animals on Day 3 and all animals treated at 50% between Days 1 and 3. The remnants did not hamper scoring of the skin reactions.

- The majority of auricular lymph nodes were considered normal in size, except for the nodes of two animals treated at 50% which were enlarged in one or both ears.

- No macroscopic abnormalities of the surrounding area were noted in any of the animals.

- No mortality occurred and no clinical signs of systemic toxicity were observed

- Body weights and body weight gains of experimental animals remained in the same range as controls over the study period.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In an LLNA skin sensitisation study, performed according to OECD/EC test guidelines, the substance was considered not be a skin sensitiser, as the SI was found not to be ≥ 3 when tested up to 50%.

Executive summary:

In accordance with OECD 429 (2010) and according to GLP principles, contact hypersensitivity to the substance was assessed by open application of the substance (in concentrations 0, 10, 25 and 50% w/w in propylene glycol) on three sequential days to the outer ear of mice (5/ dose). The SI was calculated by the ratio of the DPM/group compared to DPM/vehicle control group. No irritation of the ears was observed in any of the animals examined. The majority of auricular lymph nodes were considered normal in size, except for the nodes of two animals treated at 50% which were enlarged in one or both ears. No macroscopic abnormalities of the surrounding area were noted in any of the animals. Results of the latest reliability check were adequate. The SI values calculated for the substance concentrations 10, 25 and 50% were 1.3, 1.6 and 2.8, respectively. Since the test substance did not elicit an SI ≥ 3 when tested up to and including 50% w/w, the substance was considered not to be a skin sensitizer.