Diethyl ethylmalonate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Diethyl ethylmalonate

EC Number:

205-093-3

EC Name:

Diethyl ethylmalonate

Cas Number:

133-13-1

Molecular formula:

C9H16O4

IUPAC Name:

1,3-diethyl 2-ethylpropanedioate

Test material form:

liquid

Details on test material:

Test item: diethyl ethylmalonateCAS No.: 133-13-1Physical state: colourless liquidStorage: in cool, dry, well-ventilated place

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

Species and strain: CBA/Ca Ola Hsd miceSource: Toxi-Coop Zrt.Hygienic level at arrival: SPFHygienic level during the study: Good conventionalNumber of animals: 28 animals/main test (4 animals/treatment group)Sex: Female, nulliparous, non-pregnantAge of animals: Young adult mice; 11-12 weeks old (at start of the main test)Body weight range at starting: 18.6-23.1 gAcclimatization time: 7 daysAnimal health: Only healthy animals were usedHousing during acclimatization period: Grouped caging in small groupsHousing during the test: Grouped caging (4 animals/cage)Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.Temperature: 22 ± 3 °CRelative humidity: 30 – 70 %

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

The test item was administered at four different concentrations (10, 25, 50, 100) according to the results of the dose range finding test.

No. of animals per dose:

4

Details on study design:

Selection of test item concentrations was based on the results of a formulation evaluation and also results of preliminary irritation/toxicity tests to find an appropriate vehicle and the maximum applicable concentration according to the relevant guidelines [1-2]. Based on the preliminary test results diethyl ethylmalonate (CAS No. 133-13-1) was tested in the LLNA at concentration of 100 % as the undiluted test item and at 50 %, 25 % and 10 % (w/v) concentrations as formulations in Acetone: Olive oil 4:1 (v/v) mixture (AOO).Appropriate positive control (α-Hexylcinnamaldehyde [HCA] in 25 % (w/v) concentration), furthermore two negative control groups dosed with physiological saline (as naive control group), or with the vehicle (AOO) of the test and positive control groups, respectively, were employed.The positive control item (25 % (w/v) HCA in Acetone: Olive oil 4:1 (v/v) mixture, AOO) induced the appropriate stimulation over the control (SI = 6.9), thus confirming the validity of the assay.

Positive control substance(s):

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

Results and discussion

Positive control results:

The positive control group animals were treated with 25 % (w/v) HCA solution (dissolved in AOO) concurrent to the test item groups. No mortality, cutaneous reactions or signs of toxicity were observed in the positive control group.Significant lymphoproliferative response (SI ≥ 3) was noted for HCA (SI = 6.9). The results of the positive control item demonstrated appropriate performance of the test in accordance with the relevant guidelines and confirmed validity of the assay.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1.5

Test group / Remarks:

diethyl ethylmaloate: 100 % (undiluted)

Results 2

Parameter:

SI

Value:

0.5

Test group / Remarks:

diethyl ethylmaloate: 50% in AOO

Results 3

Parameter:

SI

Value:

0.5

Test group / Remarks:

diethyl ethylmaloate: 25% in AOO

Results 4

Parameter:

SI

Value:

0.5

Test group / Remarks:

diethyl ethylmaloate: 10 % in AOO

Cellular proliferation data / Observations:

No mortality or symptoms of systemic toxicity were observed in any treatment group. No sign of irritation (indicated by an erythema score ≥ 3) or any other local effect was observed in any treatment groups.

Any other information on results incl. tables

Test Group Name	Measured DPM/group	Group* DPM	DPN (DPM/Node)*	Stimulation Index Values
Vehicle control: AOO	8610	8585.0	1073.1	1.0
Positive control: 25 % HCA in AOO	59201	59176.0	7397.0	6.9
diethyl ethylmalonate: 100 % (undiluted)	3003	2978.0	372.3	1.5
diethyl ethylmalonate: 50 % in AOO	4453	4428.0	553.5	0.5
diethyl ethylmalonate: 25 % in AOO	4472	4447.0	555.9	0.5
diethyl ethylmalonate: 10 % in AOO	3917	3892.0	486.5	0.5
Naive control: Physiological saline	1955	1930.0	241.3	1.0

*Group DPM = measured DPM group - average DPM background

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In conclusion, under the conditions of the present Local Lymph Node Assay, diethyl ethylmalonate (CAS No. 133-13-1) tested at the maximum attainable concentration of 100% (as the undiluted form) and at concentrations of 50 %, 25 % and 10 % (w/v) as formulations in an appropriate vehicle (AOO) was shown to have no skin sensitization potential.