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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 4 April, 2012 to 7 May, 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

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

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
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

Constituent 1
Chemical structure
Reference substance name:
2-[[3-hydroxy-2,2-bis[[(1-oxoallyl)oxy]methyl]propoxy]methyl]-2-[[(1-oxoallyl)oxy]methyl]-1,3-propanediyl diacrylate
EC Number:
800-838-4
Cas Number:
1384855-91-7
Molecular formula:
Molecular formula not available for this UVCB.
IUPAC Name:
2-[[3-hydroxy-2,2-bis[[(1-oxoallyl)oxy]methyl]propoxy]methyl]-2-[[(1-oxoallyl)oxy]methyl]-1,3-propanediyl diacrylate
Test material form:
liquid: viscous
Details on test material:
- Name of test material (as cited in study report): DPHA
- Substance type: Colourless to slightly yellow viscous liquid
- Physical state: Liquid
- Purity: UVCB, 100%
- Lot/batch No.: JBHA0020T
- Expiration date of the lot/batch: 06 March 2014
- Storage condition of test material: At room temperature protected from light
- Hygroscopic: No
- Volatile: No
- Test substance handling: Use amber-coloured glassware or wrap container in aluminium foil
- Specific Gravity / Density: 1.17 g/cm3
- Stability at higher temperatures: Yes, maximum temperature: 60⁰C
- Maximum duration: 24 h
- Stability in vehicle N,N-Dimethylformamide: Not indicated
- Solubility in vehicle N,N-Dimethylformamide: Yes

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 animals (approx 11 weeks old)
- Weight at study initiation: Body weight variation was within +/- 20% of the sex mean (20 - 23 g)
- 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 d

ENVIRONMENTAL CONDITIONS

Deviations from the minimum level of daily mean relative humidity occurred.
Evaluation: Laboratory historical data do not indicate an effect of the deviations.


IN-LIFE DATES: From 04 April 2012 to 07 May 2012

Study design: in vivo (LLNA)

Vehicle:
dimethylformamide
Concentration:
0, 0.5, 1 , 2.5%
No. of animals per dose:
5
Details on study design:
The vehicle was selected based on trial formulations performed at NOTOX and on test substance data supplied by the sponsor.

RANGE FINDING TESTS:
In the interest of animal welfare and to minimize any testing likely to produce severe responses in animals, a weight of evidence analysis was performed prior to start of this study. All available information was evaluated (e.g. existing human and animal data, literature, substance data supplied by the sponsor, analysis of structure activity relationships (SAR), physicochemical properties and reactivity (pH, buffering capacity).

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. The results were evaluated according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (20011) and the Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on Classification, Labelling and Packaging of substances and mixtures.

ANIMAL ASSIGNMENT
3 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 h prior to each treatment. Homogeneity was obtained to visually acceptable levels.
Rationale for vehicle: The vehicle was selected based on trial formulations performed at NOTOX and on test substance data supplied by the sponsor.

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 h 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: all animals were killed by intraperitoneal injection (0.2 mL/animal) with Euthasol® 20% (AST Farma BV, Oudewater, The Netherlands).
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:
The six-month reliability check with alpha-hexylcinnamicaldehyde indicates that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity. See attached document 'Reliability check'.

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
EC3
Value:
> 0 - <= 0.5
Test group / Remarks:
EC3 value was determined to be between the test concentrations of 0 to 0.5%, which will result in SI of 3.
Key result
Parameter:
SI
Value:
ca. 6.2
Test group / Remarks:
0.5% test substance
Key result
Parameter:
SI
Value:
ca. 7.6
Test group / Remarks:
1% test substance
Key result
Parameter:
SI
Value:
ca. 11.1
Test group / Remarks:
2.5% test substance

Any other information on results incl. tables

Results pre-screen test:

Erythema scores and variations in ear thickness are given in detail in Table 1 and 2.

Based on these results, the highest test substance concentration selected for the main study was a 2.5% concentration.

Other results - main study:

-Skin reactions / Irritation: No irritation of the ears was observed in any of the animals examined.

-Systemic toxicity/body weights: No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. The body weight loss noted for some animals across the dose groups was considered not toxicologically significant since the changes were slight in nature and no concentration-related incidence was apparent.

-Macroscopy of the auricular lymph nodes and surrounding area: The auricular lymph nodes of all the animals at 1 and 2.5% and of some animals (3/5) at 0.5% appeared larger in size as compared to the other treated groups. The largest auricular lymph nodes were found in the higher dose groups. No macroscopic abnormalities of the surrounding area were noted in any of the animals.

Applicant's summary and conclusion

Interpretation of results:
other: Category 1A (indication of significant skin sensitising potential) based on EU CLP criteria
Conclusions:
Under the study conditions, the test substance is considered to be a strong skin sensitizer.
Executive summary:

A study was conducted to assess the contact hypersensitivity of DPHA in the mouse local lymph node assay according to OECD Guideline 429, EU Method B.42 and EPA Guideline OPPTS 870.2600 in compliance with GLP. Test substance concentrations selected for the main study were based on the results of a pre-screen test. In the main study, three experimental groups of five female CBA/J mice were treated with concentrations of 0.5, 1 or 2.5% w/w on three consecutive days by application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (N,N-Dimethylformamide). 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 and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of Disintegrations Per Minute (DPM) and a stimulation index (SI) was subsequently calculated for each group. No irritation was observed in any of the animals examined. The auricular lymph nodes of all animals at 1 and 2.5%, and of some animals (3/5) at 0.5%, appeared larger in size as compared to the other treated groups. The largest auricular lymph nodes were found in the higher dose groups. No macroscopic abnormalities of the surrounding area were noted. Mean degradations per minute (DPM)/animal for the experimental groups treated at 0.5, 1 and 2.5% were 3733, 4588 and 6646, respectively. The SI values calculated for the substance concentrations 0.5, 1 and 2.5% were 6.2, 7.6 and 11.1, respectively. These results show that the test substance elicits an SI ≥ 3. The EC3 value (the estimated test substance concentration that will give a SI = 3) was established to be between 0 and 0.5%. Under the study conditions, the test substance was considered to be a strong skin sensitizer (Beerens-Heijnen, 2012).