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Toxicological information

Skin sensitisation

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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 O.E.C.D. Testing Guideline 406 under the GLP regulations.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Pre-existing study

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Liquid at room temperature.
Details on test material:
As per IUCLID5 Sections 1.1, 1.2. and 1.4.

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male/female
Details on test animals and environmental conditions:
Male and female Dunkin-Hartley guinea pigs were obtained from D Hall Ltd, Burton on Trent, UK. The condition of the animals was assessed daily throughout an acclimatisation period of at least seven days. A clinical inspection was performed prior to study commencement to ensure the animals were suitable for the study. Healthy Guinea pigs were arbitrarily allocated to the study groups on the day prior to commencement of treatment. Animals in the main study were in a body weight range of 266 to 400 gm prior to dosing on Day 1. The guinea pigs were approximately four to six weeks old on Day 1 of the main study. Guinea pigs were accommodated in suspended polypropylene cages (six per battery) 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.

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.

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. Humidity was not actively controlled but was expected to remain within the range 40-80% Relative Humidity. 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).



Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
other: Alembicol D
Concentration / amount:
0.1 ml of 25% and 50% solutions.
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
other: Alembicol D
Concentration / amount:
0.1 ml of 25% and 50% solutions.
No. of animals per dose:
20 test, 10 control
Details on study design:
Three different preliminary screening studies were conducted to select concentration levels for: the intradermal injection phase of induction, the topical application phase of induction, and the topical application at challenge. For the intradermal injection phase of induction concentration the dorsa of two guinea pigs were clipped on the day prior to dosing. On Day 1, intradermal injections [0.1 mL per site], incorporating a range of test article concentrations, were made into the scapular zone of the denuded dorsum. Dermal reactions were individually assessed and recorded approximately 24 and 72 hours later. Selection of the concentration for the topical application phase of induction was made by treating two guinea pigs with two 0.1 mL intradermal injections of FCA into the suprascapular dorsum at least five days prior to application of the test formulation. The animals were subject to occluded, topical application of four 20 x 20 mm patches of Whatman No 4 filter paper each saturated with approximately 0.2 mL of one of the test formulations. The dressings and bandages were removed approximately 48 hours after application and the treatment sites were washed. Dermal reactions were assessed approximately 21 and 97 hours after removal of the patches. Three guinea pigs were prepared for selection of the challenge concentration by receiving two 0.1 mL intradermal injections of FCA into the suprascapular dorsum between 14 and 28 days prior to application of the test formulations. The flanks were clipped on the day before application. Each animal was subject to occluded topical application of four 12 mm Finn chambers from Biodiagnostics Ltd, Upton-upon-Severn, each loaded with approximately 0.1 mL of one of the four selected test formulations. The Finn chambers were secured by successive applications of Blenderm and Steroban. The dressings and chambers were removed after 24 hours and the treated areas of skin were washed. The location of each challenge site was marked on the skin using indelible ink. The treated areas of skin were reshaved approximately 21 hours after removal of the chambers. Dermal reactions were assessed approximately 24 and 48 hours after removal of the chambers.

The following experimental procedures were conducted for the main study:

The main study consisted of a test group of twenty females and a control group of ten female guinea pigs. For the Induction phase - intradermal injection 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 rnL 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.

Topical induction was initated on Day 7 with areas of dorsum denuded for the first phase of induction being clipped. Since the formulation selected was non-irritating in the screening test, the denuded areas were subject to application of 10% 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. Irritation or other dermal changes at the sites of occluded topical application were recorded by group on Day II.

For the Challange Phase 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% 2,3-epoxypropyl neodecanaote 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.

Dermal changes were recorded using the following scheme:
Dermal change Record: No erythema-0; Slight erythema-1; Well defined erythema-2; Moderate erythema-3; Severe erythema (beet redness)-4; In-depth damage/eschar-E; Necrosis-N; Desquamation-Q; Discoloration-D; Induration-H






Challenge controls:
None
Positive control substance(s):
no
Remarks:
No concurent positive control was used.

Results and discussion

Positive control results:
Results of the two most recent laboratory positive control studies with 2-mercaptobenzothiazole demonstated that 6/9 and 6/10 animals were sensitized which is considered a moderate to strong response for the Maximization protocol.

In vivo (non-LLNA)

Results
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
50%
No. with + reactions:
9
Total no. in group:
20
Clinical observations:
None
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50% . No with. + reactions: 9.0. Total no. in groups: 20.0. Clinical observations: None.

Any other information on results incl. tables

Data Tables of the Challenge Phase results are attached below.

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
2,3-Epoxypropyl neodecanoate elicited a positive dermal response, idicative of skin sensitization (delayed contact hypersensitivity) in four of the twenty test animals following the challange applicationof 25% test substance. An inconclusive response was seen in a further two animals and negative results in the remaining fourteen test animals. At 50% test substance concentration only four control animals had Slight erythema responses at 24 hr post challange. Seven test animals had Slight erythemia responses and two animals had well defined erythema responses at a test substance concentration of 50% at 24 hr post challange. Therefore, 2,3-epoxypropyl neodecanoate is a mild to moderate dermal sensitizer under the conditions of this study.
Executive summary:

When evaluated in a GLP, O.E.C.D. 406 Testing Guideline "Skin Sensitization" study following the Maximization protocol 2,3 -epoxypropyl neodecanoate inducted positive dermal reactions in 4/20 and 9/20 animals at 25% and 50% concentrations respectively. Therefore, 2,3 -epoxypropyl neodecanoate is a mild to moderate dermal sensitizer under the conditions of this study.