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Description of key information

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:
2014
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.
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
(July 2010)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
(May 2008)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Version / remarks:
(March 2003)
Deviations:
no
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)
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 animals (approx. 10 weeks old)
- Weight at study initiation: 21-25g
- Housing: Animals were group housed in labeld 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 (deviations from the maximum level of daily mean relative humidity occurred, but laboratory historical data do not indicate an effect of the deviations)
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 30JUL2014 to 18AUG2014
Vehicle:
propylene glycol
Concentration:
0, 50%
No. of animals per dose:
5
Details on study design:
RANGE FINDING TESTS:
In a pre-screen test, a 50% concentration was tested with two young adult animals. Each animal was treated on three consecutive days. Ear thickness measurements were conducted prior to dosing on Days 1 and 3, and on Day 6. Animals were sacrificed after the final observation.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: DPM values are presented for each animal and for the groups. A Stimulation Index (SI) is calculated for the test substance group using the individual SI values. The individual SI is the ratio of the DPM/animal compared to DPM/vehicle control group. If the results indicate a SI ≥ 3, the test substance may be regarded as a skin sensitizer.

ANIMAL ASSIGNMENT
One group of five animals was treated with the test substance concentration. 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. Correction of the purity/composition of the test substance is not applicable, since the test method requires a logical concentration range rather than specific dose levels to be dosed.
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 immediately after dosing) according to the following numerical scoring system. Furthermore, a description of all other (local) effects was recorded according to guidelines.

Necropsy: No necropsy for gross macroscopic examination was performed.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Not performed.
Positive control results:
The six-month reliability check with Alpha-hexylcinnamicaldehyde indicates that the Local Lymph Node Assay as performed at WIL Research Europe is an appropriate model for testing for contact hypersensitivity.
Parameter:
SI
Remarks on result:
other: The SI value calculated for the 50% test substance was 1.0.
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: The mean DPM/animal value for the experimental group treated with 50% test substance was 445 DPM. The mean DPM/animal value for the vehicle control group was 441 DPM.

Results Pre-screen test:

No irritation and no signs of systemic toxicity were observed in any of the animals examined. White staining of test substance remnants on the dorsal surface of the ears of both animals between Days 1 and 3 did not hamper scoring of erythema. Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values. Based on these results, the highest test substance concentration selected for the main study was a 50% concentration.

 

Other results - main study:

No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study.

No irritation of the ears was observed in any of the animals examined.White staining of test substance remnants on the dorsal surface of the ears of the experimental animals between Days 1 and 3 did not hamper scoring of erythema.

 All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals.

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

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
In a reduced LLNA skin sensitisation study, performed according to OECD/EC test guidelines, Strontium hydrogenphosphate was considered not be a skin sensitiser, as the SI appeared not to be ≥ 3 when tested up to 50%.
Executive summary:

A reduced LLNA skin sensitisation study was performed according to OECD/EC test guidelines with Strontium hydrogenphosphate. Based on a Weight-of-Evidence approach, it was considered scientifically justified to perform a reduced LLNA, with only one test group of 5 animals tested at 50% (and one vehicle control group of 5 animals).

No irritation of the ears was observed in any of the animals examined, all auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.   

No mortality occurred and no clinical signs of systemic toxicity were observed. The mean DPM/animal value was 445 DPM and 441 DPM for the experimental group treated with 50% test substance and for the vehicle control group respectively.

Based on these data, Strontium hydrogenphosphate was considered not be a skin sensitiser, as the SI appeared not to be ≥ 3 when tested up to 50%.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

A reduced LLNA skin sensitisation study was performed according to OECD/EC test guidelines with Strontium hydrogenphosphate. Based on a Weight-of-Evidence approach, it was considered scientifically justified to perform a reduced LLNA, with only one test group of 5 animals tested at 50% (and one vehicle control group of 5 animals).

No irritation of the ears was observed in any of the animals examined, all auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.   

No mortality occurred and no clinical signs of systemic toxicity were observed. The mean DPM/animal value was 445 DPM and 441 DPM for the experimental group treated with 50% test substance and for the vehicle control group respectively. The SI value calculated for the 50% test substance concentration was 1.0.

Based on these data, Strontium hydrogenphosphate was considered not be a skin sensitiser, as the SI appeared not to be ≥ 3 when tested up to 50%.


Migrated from Short description of key information:
In a reduced LLNA skin sensitisation study, performed according to OECD/EC test guidelines (Klimisch 1), Strontium hydrogenphosphate was considered not be a skin sensitiser, as the SI appeared not to be ≥ 3 when tested up to 50%.

Justification for selection of skin sensitisation endpoint:
One study available.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Since there was no indication that the test substance elicited an SI≥3 when tested up to 50%, Strontium hydrogenphosphate was considered not to be a skin sensitizer and is not classified according to Regulation (EC) 1272/2008.