Methyl 2-benzoylbenzoate

Endpoint summary

Description of key information

The test substance did not show a sensitisation potential (non-sensitizer) in the Local Lymph Node Assay.

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:

July 2014

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)

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Specific details on test material used for the study:

Identification: RCX 14-672
Chemical name: methyl-2-benzoylbenzoate
Batch no.: N14003
CAS no.: 606-28-0
EC no.: 210-112-3
Molecular formula: C15H12O3
Molecular mass: 240.3 g/mol
Description: white to light yellowish powder
Purity: >99% (gas chromatography)
Water solubility: 117.7 mg/l
Test item storage: at room temperature, protected from light
Stability: stable under storage conditions
Expiry date: 30 November 2015

Species:

mouse

Strain:

other: CBA/J Rj mice

Sex:

female

Details on test animals and environmental conditions:

Species and strain: CBA/J Rj mice
Source: ELEVAGE JANVIER, Route des Chènes Secs B.P. 4105, 53940 LE GENEST-ST-ISLE, France
Number of animals:4 animals / treatment group
Sex: Female, nulliparous, non pregnant
Age of animals at starting: Young adults, 8-12 weeks old (age-matched, within one week)
Acclimatization time: at least 5 days

Cage type: Type II. polypropylene/ polycarbonate
Bedding: Bedding available to animals during the study
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 22 ± 3 °C
Relative humidity: 30 - 70 %
Ventilation: 15-20 air exchanges/hour

Vehicle:

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

Concentration:

100, 50, 25 and 10 % (w/v)

No. of animals per dose:

Six animales per dose

Details on study design:

Based on the results of the Preliminary Compatibility Test and on the recommendations of the OECD Guideline 429 [1], the test item was tested for formulation compatibility in acetone:olive oil 4:1 (v:v) mixture (abbreviated as AOO). The highest achievable concentration was 100 % (w/v). The Preliminary Irritation / Toxicity Test I and II were performed in CBA/J Rj mice using four doses: 100, 50, 25 and 10 % (w/v) in AOO and the Preliminary Irritation / Toxicity Test III was performed in CBA/J Rj mice using two doses: 100 and 50 % (w/v) in AOO.

Based on the observations recorded in the preliminary test, the 100 % (w/v) was selected as top dose for the main test.

In the main assay, twenty-four female CBA/J Rj mice were allocated to six groups of four animals each:
- four groups received RCX 14-672 (formulated in AOO) at 100, 50, 25 and 10 % (w/v) concentrations,
- the negative control group received the vehicle (AOO),
- the positive control group received 25 % (w/v) HCA (dissolved in AOO).

The test item solutions were applied on the dorsal surface of ears of experimental animals (25 µl/ear) for three consecutive days (Days 1, 2 and 3). There was no treatment on Days 4, 5 and 6. On Day 6, the cell proliferation in the local lymph nodes was measured by incorporation of tritiated methyl thymidine (3HTdR) and the values obtained were used to calculate stimulation indices (SI).

Positive control substance(s):

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

Positive control results:

The result of the positive control substance hexylcinnamaldehyde (HCA) dissolved in the same vehicle was used to demonstrate the appropriate performance of the assay. The positive control substance was examined at a concentration of 25 % in the relevant vehicle (AOO) using CBA/J Rj mice. No mortality, cutaneous reactions or signs of toxicity were observed for the positive control substance in the study. A significant lymphoproliferative response (stimulation index value of 12.4) was noted for HCA in the main experiment. This value was considered to confirm the appropriate performance of the assay.

Key result

Parameter:

SI

Value:

1.7

Test group / Remarks:

100% in acetone:olive oil (4:1)

Key result

Parameter:

SI

Value:

1.1

Test group / Remarks:

50% in acetone:olive oil (4:1)

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

25% in acetone:olive oil (4:1)

Key result

Parameter:

SI

Value:

0.8

Test group / Remarks:

10% in acetone:olive oil (4:1)

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

Acetone:olive oil (4:1), negavtive control

Key result

Parameter:

SI

Value:

12.6

Test group / Remarks:

hexylcinnamaldehyde (positive control)

No mortality or signs of systemic toxicity were observed during the study. Test item precipitate was observed on the ears of the experimental animals in the 100 % (w/v) dose group on Days 1-6, in the 50 % (w/v) group on Days 1-5 and in the 25 % (w/v) dose group on Days 1-3. Alopecia was observed in the 100 % (w/v) dose group on Days 2-6 and in the 50 % (w/v) group on Days 3-6.

Interpretation of results:

not sensitising

Conclusions:

Under the conditions of the present assay, RCX 14-672, tested in a suitable vehicle, did not show a sensitisation potential (non-sensitizer) in the Local Lymph Node Assay.

Executive summary:

The aim of this study was to determine the skin sensitisation potential of RCX 14-672 following dermal exposure. The study was performed with vertebrate animals as no regulatory in vitro alternative is available. The minimum number of animals was used,

corresponding to the regulatory guidelines being followed. Based on the results of the Preliminary Compatibility Test and on the recommendations of the OECD Guideline 429 [1], the test item was tested for formulation compatibility in acetone:olive oil 4:1 (v:v) mixture (abbreviated as AOO). The highest achievable concentration was 100 % (w/v).

The Preliminary Irritation / Toxicity Test I and II were performed in CBA/J Rj mice using four doses: 100, 50, 25 and 10 % (w/v) in AOO and the Preliminary Irritation / Toxicity Test III was performed in CBA/J Rj mice using two doses: 100 and 50 % (w/v) in AOO. Based on the observations recorded in the preliminary test, the 100 % (w/v) was selected as top dose for the main test. In the main assay, twenty-four female CBA/J Rj mice were allocated to six groups of four animals each:

- four groups received RCX 14-672 (formulated in AOO) at 100, 50, 25 and 10 % (w/v) concentrations,

- the negative control group received the vehicle (AOO),

- the positive control group received 25 % (w/v) HCA (dissolved in AOO).

The test item solutions were applied on the dorsal surface of ears of experimental animals (25 μl/ear) for three consecutive days (Days 1, 2 and 3). There was no treatment on Days 4, 5 and 6. On Day 6, the cell proliferation in the local lymph nodes was measured by incorporation of tritiated methyl thymidine (3HTdR) and the values obtained were used to calculate stimulation indices (SI). No mortality or systemic clinical signs were observed during the study. Test item precipitate was observed on the ears of the experimental animals in the 100 % (w/v) dose group on Days 1-6, in the 50 % (w/v) group on Days 1-5 and in the 25 % (w/v) dose group on Days 1-3. Alopecia was observed in the 100 % (w/v) dose group on Days 2-6 and in the 50 % (w/v) group on Days 3-6. The observed stimulation index values were 1.7, 1.1, 1.0 and 0.8 at concentrations of 100, 50, 25 and 10 % (w/v), respectively. The result of the positive control substance a-Hexylcinnamaldehyde (HCA) dissolved in the same vehicle was used to demonstrate the appropriate performance of the assay [1]. A significant lymphoproliferative response (stimulation index value of 12.4) was noted for the positive control chemical, this result confirmed the validity of the assay.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of the available study, methyl-2-benzoylbenzoate does not need to be classified as a skin sensitiser according to Regulation EC 1272/2008 and Directive 67/548/EEC.