Nonanoic acid, 2-oxiranylmethyl ester, branched

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to the O.E.C.D. test guideline 406 with GLP compliance.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Test material

Test material information

Constituent 1

Reference substance name:

2,3-epoxypropyl neodecanoate

EC Number:

247-979-2

EC Name:

2,3-epoxypropyl neodecanoate

Cas Number:

26761-45-5

Molecular formula:

C13H24O3

IUPAC Name:

Oxiran-2-ylmethyl 2-ethyl-2,5-dimethylhexanoate

Constituent 2

Reference substance name:

Neodecanoic acid, oxiranylmethyl ester

IUPAC Name:

Neodecanoic acid, oxiranylmethyl ester

Test material form:

other: Colorless liquid at room temperature.

Details on test material:

As per IUCLID5 Sections 1.1. 1.2. 1.4. and 4.1. for 2,3-epoxypropyl neodecanoate, REACH Registration: 01-2119431597-33-0000.

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

Non-pregnant female Dunkin-Hartley guinea pigs were obtained from D Hall Ltd, Burton on Trent. The condition of the animals was assessed daily throughout an acclimatisation period of at least seven days. Animals in the main study were in a body weight range of 266 to 400 gm prior to dosing on Day 1. Based on information from the supplier the guinea pigs were approximately four to six weeks old on Day 1.

Guinea pigs were housed in suspended polypropylene cages with open tops, solid floors and stainless steel mesh front panels. Each cage held up to five animals and was relined with a whitewood bedding, Grade 10 Woodflakes from Datesand Ltd, Brookiands, three times each week. Each batch of bedding had been analysed for specific constituents.

The animal room used during the acclimatisation and observation periods was designed to permit at least 10 air changes per hour and to maintain environmental conditions of 19 to 25°C and a Relative Humidity range of 40-80%. Recordings of maximum and minimum temperature and humidity were made twice daily and any minor deviations from the expected ranges were noted in the study record. The rooms were illuminated by fluorescent strip-lights for twelve hours daily (typically 06:00 to 18:00 hours GMT).

SQC FD 1 (pelleted) diet from Special Diets Services Ltd., Witham was freely available to the animals at all times. Each batch of diet had been analysed for specific constituents. Mains water was provided, ad libitum, via cage mounted water bottles. The water is periodically analysed for specific contaminants. No contaminants were expected to be present in diet or water at levels which might interfere with achieving the objective of the study.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal

Vehicle:

other: Alembicol D

Induction 2

Concentration / amount:

Intradermal induction - 25%, topical induction - 100%, Challenge Phase - 25 and 50%

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: Alembicol D

Challenge 2

Concentration / amount:

Intradermal induction - 25%, topical induction - 100%, Challenge Phase - 25 and 50%

No. of animals per dose:

10 control and 20 treated

Details on study design:

For the Intradermal Induction Phase the dorsum overlaying the scapulae of each guinea pig was clipped on the day before treatment commenced. On Day 1 three paired intradermal injections (0.1 mL per site) were placed in single rows parallel to and on either side of the dorsal mid-line of each guinea pig such that the anterior and posterior injection sites marked the corners of an approximate 20 x 40 mm area. The middle injection sites were positioned close to the anterior sites. The concentration of test article selected after the first screen was administered as follows:
Site Test group Control group
Anterior FCA FCA
Middle Test Sub, 25% m/v in Alembicol D Alembicol D
Posterior Test Sub, 25% mn/v in FCA 50% v/v Alembicol D in FCA

Topical Induction was begun on Day 7. The areas of dorsum denuded for the first phase of induction were clipped. Since the formulation selected was non-irritating in the screening test, the denuded areas were subject to application of 10% m/m sodium lauryl sulphate in petrolatum on Day 7. A dose of approximately 0.4 mL was rubbed into the dorsurn using a gloved finger. This procedure is intended to produce a mild irritation of the skin to be treated on the following day. On Day 8 each dorsum was shaved. Approximately two hours later the area of skin including the intradermal injection sites was subject to application of a 25 x 45 mm patch of Whatman No 4 filter paper loaded with approximately 0.5 mL of undiluted test substance (test animals) or Alembicol D alone (control group). Occlusion of the treated skin was effected by successive layers of Blenderm and Steroban. The patches and dressings remained in place for 48 hours. The treated areas of skin were washed with arachis oil. Irritation or other dermal changes at the sites of occluded topical application were recorded by group on Day II.

The Challenge Phase was initiated when both flanks of all guinea pigs were clipped on Day 21 and shaved to remove hair stubble on Day 22. Approximately two hours later the left flank of each animal was subject to application of a 12 mm Finn chamber loaded with approximately 0.1 mL vehicle. Finn chambers containing the formulations selected for challenge, 50 and 25% m/m test substance in Alembicol D were applied to the right flank. The chambers were kept in place by successive layers of Blenderm and Steroban. The chambers and dressings were removed approximately 24 hours after application and the treated areas of skin were washed with arachis oil. Challenge site locations were marked with indelible ink immediately after the washing procedure. The challenge sites were reshaved approximately 21 hours after removal of the chambers. Dermal responses to challenge were assessed approximately 24 and 48 hours after removal of the chambers. Responses to challenge were recorded individually.

Test and control guinea pigs were observed daily for clinical signs of reaction to treatment. The guinea pigs were weighed on Day 1 and on Day 25.

Challenge controls:

No

Positive control substance(s):

yes

Remarks:

2-mercaptobenzothiazole (MBTZ), not concurrent.

Results and discussion

Positive control results:

Approximately 60% of the animals demonstrated dermal reactions during the Challenge Phase.

In vivo (non-LLNA)

Results

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

25%

No. with + reactions:

4

Total no. in group:

20

Clinical observations:

None

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 25%. No with. + reactions: 4.0. Total no. in groups: 20.0. Clinical observations: None.

Any other information on results incl. tables

Dermal reactions seen at the higher concentration (50% rn/rn) test substance challenge sites among the test animals were generally more marked than at the equivalent control sites and included well defined erythema, development of eschar and scabbing and widespread induration of the treated areas. Cases of necrosis and fissuring were also apparent, indicative of extensive disruption of the dermis. Nine of the twenty test animals were adjudged to have individual responses that were more marked than the maximum control response at this site. The extent of reactions across the treated group, the degree of response and duration of the changes were all indicative of an enhanced dermal reaction when compared with the control group but, despite no evidence for marked irritation reactions at this concentration or at higher concentrations applied in the topical screening tests, it may be argued that the reactions elicited by the high challenge level were due to an inflammatory/irritant response. When results are assessed only on the response seen at sites exposed to the lower challenge concentration (25%), there is no indication of irritation in the control group and only four of the twenty test group animals (20%) showed reactions which were more marked or more persistent than at the equivalent control group site with two further animals showing equivocal responses

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information For the purpose of Classification and Labeling. Criteria used for interpretation of results: EU

Conclusions:

With 20% (4/20) of the test substance treated guinea pigs exhibiting positive dermal reaction upon challenge the test substance is considered to be a mild skin sensitizer based upon the criteria defined in S. C. Gad and C. P. Chengelis, "Acute toxicology Testing". 2nd Ed. Academic Press, 1998. However, these results are insufficient to support Classification and Labeling as a skin sensitizer.

Executive summary:

The structural analog test substance, 2,3-epoxypropyl neodecanoate was accessed for skin sensitization potential in an O.E.C.D. test guideline 406 guinea pig Maximization study. With 20% (4/20) of the test substance treated guinea pigs exhibiting positive dermal reaction upon challenge, the test substance is considered to be a mild skin sensitizer. However, these results are insufficient to support Classification and Labeling as a skin sensitizer that requires a 30% positive dermal reaction response. Based on these findings, Neononanoic acid glycidyl ester is unlikely to be a skin sensitizer.