1,12-dodecanediyl bismethacrylate

Endpoint summary

Description of key information

1,12 -dodecanediol bismethacrylate is considered to be a skin sensitizer based on the weight-of-evidence approach.

The murine Local Lymph Node Assay (LLNA, OECD 429) was performed to evaluate the skin sensitization potential of 1,10-decanediol diacrylate, an analogue of 1,12 -dodecanediol bismethacrylate. The substance gave a positive result in this test, indicative of skin sensitization properties.

A QSAR (VEGA / CAESAR) predicts also that 1,12 -dodecanediol bismethacrylate has skin sensitizing properties.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

12 April 2013 - 28 May 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

as the dose formulations of the main test were delivered in stoppered plastic tubes, they were stirred using vortex prior to application.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

other: CBA/J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: breeder: Janvier, Le Genest-Saint-Isle, France.
- Age at study initiation: the animals of the preliminary test were approximately 11 weeks old on the day of treatment, and the animals of the main test were approximately 8 weeks old.
- Mean body weight at study initiation: the animals of the preliminary test had a mean body weight of 22.5 g (range: 21.7 g to 23.7 g) and the animals of the main test had a mean body weight of 20.1 g (range: 18.5 g to 22.3 g).
- Fasting period before study: no
- Housing: polycarbonate cages
- Diet: SSNIFF R/M-H pelleted diet (free access)
- Water: tap water filtered with a 0.22 µm filter (free access)
- Acclimation period: for a period of 6 days before the beginning of the study

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2°C
- Humidity (%): 50 ± 20%
- Air changes (per hr): approximately 12 cycles/hour of filtered, non-recycled air
- Photoperiod (hrs dark / hrs light): 12 h/12 h

IN-LIFE DATES: 15 May 2013 to 27 May 2013

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

The maximum concentration tested in the main test was selected according to the criteria specified in the OECD Guidelines and on the basis of the data that was obtained in the preliminary test:
- the vehicle should be selected on the basis of producing a homogeneous preparation suitable for application of the test item,
- the concentrations were selected from the concentration series 100% (when test item can be sampled by a pipette), 50%, 25%, 10%, 5%, 2.5%, 1%, 0.5%, etc,
- the maximum concentration of the test item was selected to avoid overt systemic toxicity and excessive local skin irritation the latter being defined by an = 25% increase of the ear thickness.

No. of animals per dose:

- preliminary test: 4 nulliparous and non pregnant females,
- main test: 28 nulliparous and non pregnant females.

Details on study design:

RANGE FINDING TESTS:
The maximum concentration tested in the main test was selected according to the criteria specified in the OECD Guidelines and on the basis of the data that was obtained in the preliminary test:
- the vehicle should be selected on the basis of producing a homogeneous preparation suitable for application of the test item,
- the concentrations were selected from the concentration series 100% (when test item can be sampled by a pipette), 50%, 25%, 10%, 5%, 2.5%, 1%, 0.5%, etc,
- the maximum concentration of the test item was selected to avoid overt systemic toxicity and excessive local skin irritation the latter being defined by an = 25% increase of the ear thickness.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: murine Local Lymph Node Assay
- Criteria used to consider a positive response: stimulation Index SI >= 3 and dose-relationship; additional consideration of ear thickness

TREATMENT PREPARATION AND ADMINISTRATION:
- Treatment preparation: The test item was prepared at the chosen concentrations in the vehicle.
The positive control was dissolved in AOO at the concentration of 25% (v/v).
- Administration:
On days 1, 2 and 3, at approximately the same time each day, a dose-volume of 25 µL of the control or dose formulation preparations was applied to the dorsal surface of both ears, using an adjustable pipette fitted with a plastic tip.
In order to avoid licking and to ensure an optimized application of the test materials, and to facilitate ear thickness measurement, the animals were placed under light isoflurane anesthezia during the administration.
No massage was performed but the tip was used to spread the preparation over the application sites. No rinsing was performed between each application.
The dose formulations were stirred manually throughout the dosing procedure.

Positive control substance(s):

other: a-hexyl cinnamaldehyde (HCA)

Statistics:

no

Positive control results:

The threshold positive value of 3 for the SI was reached in the positive control group (SI = 6.68).

Key result

Parameter:

EC3

Value:

6

Cellular proliferation data / Observations:

No unscheduled deaths and no clinical signs indicative of systemic toxicity were observed during the observation period. Body weight of animals was unaffected by the test item treatment.
At the concentration of 25%, erythema was observed on day 3 and on day 4/4 and in 2/4 females, respectively. Dryness of ear skin was noted in 3/4 and 4/4 females at the concentrations of 10 and 25%, respectively on day 6.
No notable increase in ear thickness was observed at 1, 2.5, 5 and 10%. But a significant increase in ear thickness of 50.50% was observed in females treated at the concentration of 25% on day 6.
The threshold positive value of 3 for the SI was reached in the positive control group (SI = 6.68). The experiment was therefore considered valid.
A significant dose-related lymphoproliferation (SI > 3) was noted at 10 and 25%.

Based on the positive SI value observed at concentrations of 10% and 25% (7.12 and 7.72 respectively) , the test item should be considered as a skin sensitizer. As irritation was also observed at concentration of 25%, it might be possible to conclude that an excessive local irritation may be involved in false positive lymphoproliferation responses at this concentration.
Nevertheless, in the absence of local irritation at 10%, the significant lymphoproliferative response observed at this concentration was attributed to delayed contact hypersensitivity. The EC3value is equal to 6%.

Table of results (main study):

Treatment	Concentration (%)	Irritation level	Stimulation Index (SI)
Test item	1	I	1.01
Test item	2.5	I	1.21
Test item	5	I	1.93
Test item	10	I	7.12
Test item	25	III	7.72
HCA	25	-	6.68

-: not recorded,

I: non-irritant (increase in ear thickness < 10%),

III: irritant (increase in ear thickness = 25%),

HCA: a-hexyl cinnamaldehyde.

 

 

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

Under the experimental conditions of this study, the test item gave a positive result in the murine Local Lymph Node Assay, indicative of skin sensitization properties.

Executive summary:

The objective of this study was to evaluate the potential of the test item to induce contact hypersensitivity using the murine Local Lymph Node Assay (LLNA). This study was conducted in compliance with OECD Guideline No. 429 and the principles of Good Laboratory Practices.

 

Methods

To assess the irritant potential of the test item (through ear thickness measurement), a preliminary test was first performed in order to define the test item concentrations to be used in the main test. Two groups of two female mice received the test item by topical route to the dorsal surface of both ears (one concentration per ear) on days 1, 2 and 3 at concentrations of 10, 25, 50 or 100% under a dose-volume of 25 µL. From day 1 to day 3 then on day 6, the thickness of both ears of each animal was measured and the local reactions were recorded. Each animal was observed at least once a day for mortality and clinical signs. Body weight was recorded once during the acclimation period and then on days 1 and 6. On completion of the observation period, the animals were sacrificed then discarded without macroscopic post-mortem examination.

     

In the main test, five groups of four female mice received the test item by topical route to the dorsal surface of both ears on days 1, 2 and 3 at concentrations of 1, 2.5, 5, 10 or 25% under a dose-volume of 25 µL. One negative control group of four females received the vehicle (acetone/olive oil(4/1; v/v)) under the same experimental conditions. Additionally, one positive control group of four females received the positive control, a-hexylcinnamaldehyde (HCA), at 25% in a mixture acetone/olive oil (4/1; v/v) under the same experimental conditions.

From day 1 to day 3 then on day 6, the thickness of the left ear of each animal was measured, except in animals of the positive control group, and the local reactions were recorded. Each animal was observed at least once a day for mortality and clinical signs. Body weight was recorded once during the acclimation period, and then on days 1 and 6.

After 2 days of resting, on day 6, the animals received a single intravenous injection of tritiated methyl thymidine (3H-TdR). Approximately 5 hours later, the animals were sacrificed and the auricular lymph nodes were excised. The proliferation of lymphocytes in the lymph node draining the application site was measured by incorporation of 3H-TdR.

The results are expressed as disintegrations per minute (dpm) per group and as dpm/node. The obtained values were used to calculate Stimulation Indices (SI).

 

Results

No unscheduled deaths and no clinical signs indicative of systemic toxicity were observed during the observation period. Body weight of animals was unaffected by the test item treatment.

At the concentration of 25%, erythema was observed on day 3 and on day 4/4 and in 2/4 females, respectively. Dryness of ear skin was noted in 3/4 and 4/4 females at the concentrations of 10 and 25%, respectively on day 6.

No notable increase in ear thickness was observed at 1, 2.5, 5 and 10%. But a significant increase in ear thickness of 50.50% was observed in females treated at the concentration of 25% on day 6.

The threshold positive value of 3 for the SI was reached in the positive control group (SI = 6.68). The experiment was therefore considered valid.

A significant dose-related lymphoproliferation (SI > 3) was noted at 10 and 25%.

 

Based on the positive SI value observed at concentrations of 10% and 25% (7.12 and 7.72 respectively) , the test item should be considered as a skin sensitizer. As irritation was also observed at concentration of 25%, it might be possible to conclude that an excessive local irritation may be involved in false positive lymphoproliferation responses at this concentration.

Nevertheless, in the absence of local irritation at 10%, the significant lymphoproliferative response observed at this concentration was attributed to delayed contact hypersensitivity. The EC₃value is equal to 6%.

 

Conclusion

Under the experimental conditions of this study, the test item gave a positive result in the murine Local Lymph Node Assay, indicative of skin sensitization properties. According to the EC₃value obtained, the test item should be considered as a moderate sensitizer.

 

According to the criteria of CLP Regulation,the test item should be classified as skin sensitizer (category 1 and sub-category 1B) and assigned the signal word "warning" and the hazard statement "H317: May cause an allergic skin reaction".

 

Reference 2

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE
VEGA
It is implemented inside the VEGA online platform, accessible at:http://www.vega-qsar.eu/
The model extends the original CAESAR model, freely available at: http://www.caesarproject.eu/software/

2. MODEL (incl. version number)
Skin Sensitisation model (CAESAR) (version 2.1.5)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILE used : CC(=C)C(=O)OCCCCCCCCCCCCOC(=O)C(C)=C

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
[Explain how the model fulfils the OECD principles for (Q)SAR model validation. Consider attaching the QMRF or providing a link]
QMRF is attached in this Robust Study Summary.

- Defined endpoint: skin sensitisation on mouse

- Unambiguous algorithm: The model consists in an Adaptive Fuzzy Partition (AFP) based on 8 descriptors. The AFP produces as output two values O(positive) and O(negative) that represent the belonging degree respectively to the sensitizer and non-sensitizer classes. The input compound is assigned to the class having this degree value higher than 0.5, unless the difference between the values of the two degrees is lower than the threshold 0.001; in this case, the belonging to one class or the other is not sure, thus no prediction is made. Full reference and details of the used formulas can be found in: Chaudhry, Q., Piclin, N., Cotterill, J., Pintore, M., Price, N. R., Chrétien, J. R. and Roncaglioni, A. (2010). Global QSAR models of skin sensitisers for regulatory purposes., Chem Cent J 4 Suppl 1, S5.
The descriptors used by the AFP model are the following:
- nN: Number of nitrogen atoms
- GNar: Narumi geometrc topological index
- MDDD: Mean Distance Degree Deviation
- X2v: Valence connectivity index chi-2
- EEig10r: Eigenvalue 10 from the edge adjacency matrix weighted by resonance integrals
- GGI8: Topological charge index of order 8
- nCconj: Number of non aromatic conjugated C(sp2)
- O-058: Atom-centred fragment =O
The descriptors were calculated, in the original model, by means of MDL and dragonX software and are now entirely calculated by an in-house software module in which they are implemented as described in: R. Todeschini and V. Consonni, Molecular Descriptors for Chemoinformatics, Wiley- VCH, 2009.

- Defined domain of applicability:
The applicability domain of predictions is assessed using an Applicability Domain Index (ADI) that has values from 0 (worst case) to 1 (best case). The ADI is calculated by grouping several other indices (see below), each one taking into account a particular issue of the applicability domain. Most of the indices are based on the calculation of the most similar compounds found in the training and test set of the model, calculated by a similarity index that consider molecule's fingerprint and structural aspects (count of atoms, rings and relevant fragments).
For each index, including the final ADI, three intervals for its values are defined, such that the first interval corresponds to a positive evaluation, the second one corresponds to a suspicious evaluation and the last one corresponds to a negative evaluation.

- Appropriate measures of goodness-of-fit and robustness and predictivity:
See the attached QMRF for details on each index. Measured applicability domain scores :
1-Similar molecules with known experimental value. This index takes into account how similar are the first two most similar compounds found. Values near 1 mean that the predicted compound is well represented in the dataset used to build the model, otherwise the prediction could be an extrapolation.
2-Accuracy of prediction for similar molecules. This index takes into account the classification accuracy in prediction for the two most similar compounds found. Values near 1 mean that the predicted compounds falls in an area of the model's space where the model gives reliable predictions (no misclassifications), otherwise the lower is the value, the worse the model behaves.
3-Concordance for similar molecules . This index takes into account the difference between the predicted value and the experimental values of the two most similar compounds. Values near 0 mean that the prediction made disagrees with the values found in the model's space, thus the prediction could be unreliable.
4-Atom Centered Fragments similarity check. This index takes into account the presence of one or more fragments that aren't found in the training set, or that are rare fragments. First order atom centered fragments from all molecules in the training set are calculated, then compared with the first order atom centered fragments from the predicted compound; then the index is calculated as following: a first index RARE takes into account rare fragments (those who occur less than three times in the training set), having value of 1 if no such fragments are found, 0.85 if up to 2 fragments are found, 0.7 if more than 2 fragments are found; a second index NOTFOUND takes into account not found fragments, having value of 1 if no such fragments are found, 0.6 if a fragments is found, 0.4 if more than 1 fragment is found.
5-Model descriptors range check. This index checks if the descriptors calculated for the predicted compound are inside the range of descriptors of the training and test set. The index has value 1 if all descriptors are inside the range, 0 if at least one descriptor is out of the range.
6-Global AD Index. The final global index takes into account all the previous indices, in order to give a general global assessment on the applicability domain for the predicted compound.

MODEL STATISTICS
Following, statistics obtained applying the model to its original dataset:
¿ Training set: n = 167; Accuracy = 0.91; Specificity = 0.74; Sensitivity = 0.95
¿ Test set: n = 42; Accuracy = 0.93; Specificity = 0.75; Sensitivity = 0.97

5. APPLICABILITY DOMAIN [Explain how the substance falls within the applicability domain of the model]
Predicted substance is into the Applicability domain of the model (ADI > 0.9). AD index of 0.912.
The list of 6 most similar compounds found in the training and tes set of the model was reported in the prediction report, with their description and relevant in information (predicted and experimental data).
Similar molecules with known experimental value : Similarity index = 0.831. Strongly similar compounds with known experimental values in the training set have been found.
Concordance for similar molecules: Concordance index = 1 : Similar molecules found in the training set have experimental values that agree with the predicted value.
Accuracy of prediction for similar molecules: Accuracy index = 1 : Accuracy of prediction for similar molecules fould in the training set is good.
Atom centered fragments similarity check: ACF matching index = 1 : All atom centered fragment of the compound have been found in the compounds of the training set.
Model descriptors range check: Descriptors range check = true : Descriptors for this compound have values inside the descriptor range of the compounds of the training set.

6. ADEQUACY OF THE RESULT [Explain how the prediction fits the purpose of classification and labelling and/or risk assessment]
The QSAR prediction is that the substance is skin sensitizer.
The results of this QSAR is used in the Weight of Evidence approach to classify the registered substance as skin sensitizer.

Qualifier:

equivalent or similar to guideline

Guideline:

other: REACH Guidance on QSARs R.6

Version / remarks:

2008

Deviations:

not applicable

Specific details on test material used for the study:

SMILE : O=C(OCCCCCCCCCCCCOC(=O)C(=C)C)C(=C)C

Remarks on result:

no indication of skin sensitisation based on QSAR/QSPR prediction

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

In vivo skin sensitisation study (2013)/ read-across:

The objective of this study was to evaluate the potential of the test item to induce contact hypersensitivity using the murine Local Lymph Node Assay (LLNA). This study was conducted in compliance with OECD Guideline No. 429 and the principles of Good Laboratory Practices.

In the main test, five groups of four female mice received the test item by topical route to the dorsal surface of both ears on days 1, 2 and 3 at concentrations of 1, 2.5, 5, 10 or 25% under a dose-volume of 25 µL. One negative control group of four females received the vehicle (acetone/olive oil(4/1; v/v)) under the same experimental conditions. Additionally, one positive control group of four females received the positive control, a-hexylcinnamaldehyde (HCA), at 25%in a mixture acetone/olive oil (4/1; v/v)under the same experimental conditions.

No unscheduled deaths and no clinical signs indicative of systemic toxicity were observed during the observation period. Body weight of animals was unaffected by the test item treatment.

At the concentration of 25%, erythema was observed on day 3 and on day 4/4 and in 2/4 females, respectively. Dryness of ear skin was noted in 3/4 and 4/4 females at the concentrations of 10 and 25%, respectively on day 6.

No notable increase in ear thickness was observed at 1, 2.5, 5 and 10%. But a significant increase in ear thickness of 50.50% was observed in females treated at the concentration of 25% on day 6.

The threshold positive value of 3 for the SI was reached in the positive control group (SI = 6.68). The experiment was therefore considered valid.

A significant dose-related lymphoproliferation (SI > 3) was noted at 10 and 25%.

Based on the positive SI value observed at concentrations of 10% and 25%, the test item should be considered as a skin sensitizer. As irritation was also observed at concentration of 25%, it might be possible to conclude that an excessive local irritation may be involved in false positive lymphoproliferation responses at this concentration.

Nevertheless, in the absence of local irritation at 10%, the significant lymphoproliferative response observed at this concentration was attributed to delayed contact hypersensitivity. The EC3 value is equal to 6%.

Under the experimental conditions of this study, the test item gave a positive result in the murine Local Lymph Node Assay, indicative of skin sensitization properties. According to the EC3 value obtained, the test item should be considered as a moderate sensitizer.

QSAR : skin sensitisation model CAESAR / VEGA

The prediction shows that 1,12 -dodecanediol bismethacrylate is skin sensitizer.

The prediction is reliable and 1,12 -dodecanediol bismethacrylate is into the Applicability Domain of the model.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the weight-of-evidence approach, a classification as skin sensitizer (category 1 and sub-category 1B) of 1,12 -dodecanediol bismethacrylate is required according to the Regulation EC N°1272/2008.

Justification: Based on the results of the LLNA, the EC3 value is equal to 6% corresponding to the category 1B of CLP.