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Description of key information

The substance N-(n-Octyl)pyrrolidone was tested for its sensitizing effect on the skin of the guinea pig in the Maximization Test based on the method of Magnusson and Kligman (GLP OECD guideline study).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
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:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Principles of method if other than guideline:
The substance N-(n-Octyl)pyrrolidone was tested for its sensitizing effect on the skin of the guinea pig in the Maximization Test based on the method of Magnusson and Kligman.
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
An LLNA does not need to be conducted because adequate data from a GPMT are available.
Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Pirbright White, Dunkin Hartley HOE DHPK [SPF-LAC] BÖ; Lippische Versuchstierzucht, Hagemann GmbH & Co. KG, D-W4923 Extertal 1, FRG
- Age at study initiation: Young adult animals
- Weight at study initiation: 278 - 349 g
- Housing: 5 per cage
- Diet: Kliba 341.4 mm (Kaninchen-Meerschweinchen-Haltungsdiät); Klingentalmühle AG, CH-4303 Kaiseraugst, Switzerland ad libitum
- Water: Water ad libitum (tap water; about 2 g of ascorbic acid per 10 l water was added to the drinking water twice a week)
- Acclimation period: 6 days before the beginning of the study in the laboratory for dermal toxicity


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12


Route:
intradermal and epicutaneous
Vehicle:
other: olive oil DAB 9
Concentration / amount:
1st application: Induction 50 %
2nd application: Challenge 25 %
Route:
epicutaneous, open
Vehicle:
other: olive oil DAB 9
Concentration / amount:
1st application: Induction 50 %
2nd application: Challenge 25 %
No. of animals per dose:
Number of animals per control group: 10
Number of animals of the test group: 20
Details on study design:
Conduct and aim of the study
Weight check of the individual animals:
before intradermal induction and before the end of the study.

Clipping of the test animals:
if required, about 3 hours before each test substance application at the appropriate application sites.

General observations:
a check was made twice each workday and once on Saturdays, Sundays and on public holidays for general observations and for any dead or moribund animal.

Form of application:
- intradermal and percutaneous occlusive
Intradermal induction using adjuvant technique has been recommended by the author guidelines to enhance immune response so that weak sensitizing compounds can be detected in this assay. Dermal induction resp. challenge is simulating practical exposure conditions.

Selection of the vehicle:
- olive oil was used as vehicle because of good solubility

Preparation of the test substance formulations:
- immediately before test substance application with Ultraturrax or with a magnetic stirrer (only adjuvant preparation)
- Formulations of the test substance were prepared gravimetrically; all concentrations were determined in weight/weight.

Pretest
Amount applied:
2 x 2 cm filter paper strips were applied to the skin of the flanks under an occlusive dressing (the bandage consists of rubberized linenpatches 4 x 4 cm from Russka and Fixomull Stretch (adhesive fleece) from Beiersdorf AG). In the case of liquids the test filter paper strip was soaked in the test substance formulation; thus, the animals were exposed to about 0.15 g of the test substance formulation.

Exposure period:
The test substance was applied 2 times for 24 hours within a period of 96 hours in order to detect non-specific phenomena that are not caused by a sensitization reaction but could possibly be attributed to a shift in the irritation threshold.

Site of application:
- flank, respective on the same area

Number of test animals:
- 4 per test concentration

Readings:
- about 24 and 48 h after the beginning of application

Assessment of skin findings
(according to Draize, J.H. (1959): Appraisal of the
Safety of Chemicals in Foods, Drugs and Cosmetics. The Association of Food and Drug Officials of the United States Austin, Texas):

1. Erythema and eschar formation

0: No erythema
1: Very slight erythema (barely perceptible)
2: Well defined erythema
3: Moderate to severe erythema
4: Severe erythema (beet-redness) to slight, eschar formation (injuries in depth)

2. Edema formation

0: No edema
1: Very slight edema (barely perceptible)
2: Slight edema (edges of area well defined by definite rising)
3: Moderate edema (raised approx. 1 mm)
4: Severe edema (raised more than 1 mm and extending beyond the area of exposure)


Main test
Number of animals per control group 10
Number of animals of the test group 20

Induction
Intradermal induction:
- 6 intradermal injections in groups of two per animal

Injections for the test group:
A) front row: 2 injections each of 0.1 ml Freund's adjuvant without test substance emulsified with 0.9% aqueous NaC1-solution in a ratio of 1:1

B) middle row: 2 injections each of 0.1 ml of the test substance formulation

C) back row: 2 injections each of 0.1 ml Freund's adjuvant/ 0.9% aqueous NaC1-solution (1:1) with test substance

Injections for control groups 1 and 2:
- The animals were given the same injections (A, B, C) but without test substance, only with the formulating agent .

Site of application:
-shoulder

Readings:
- 24 h after the beginning of application

Assessment of the skin findings:
analogous to the pretest

Percutaneous induction:
- Percutaneous induction was carried out one week after intradermal induction.

Amount applied:
2 x 4 cm filter paper strips were applied to the skin of the shoulder under an occlusive dressing (the bandage consists of rubberized linenpatches 4 x 4 cm from Russka and Fixomull Stretch (adhesive fleece) from Beiersdorf AG). The filter paper strip was soaked in the test substance formulation; thus, the animals were exposed to about 0.3 g of the test substance formulation.

- The control groups were treated analogously to the test group but only with the solvent (olive oil DAB 9) without the test substance.

Duration of exposure:
- 48 hours

Site of application:
- shoulder, same area as in the case of the previous intradermal application

Readings:
- 48 h after the beginning of application

Assessment of skin findings:
- analogous to the pretest

Challenge
Test concentration: non-irritant concentration
First challenge 21 days after intradermal induction

Amount applied:
2 x 2 cm filter paper strips were applied to the skin of the flank under an occlusive dressing (the bandage consists of rubberized linenpatches 4 x 4 cm from Russka and Fixomull Stretch (adhesive fleece) from Beiersdorf AG). The test filter paper strip was soaked in the test substance
formulation; thus the animals were exposed to about 0.15 g of the test substance formulation.

Challenge:
- treatment of the test group and of control group 1 with the test substance formulation. Additionally olive oil DAB 9 was applied as a vehicle. Control group 2 only received olive oil DAB 9.

Duration of exposure:
- 24 hours

Site of application:
- intact clipped flank

Readings:
- 24 and 48 h after the removal of the patch

Assessment of skin findings:
analogous to the pretest

Positive control
A positive control (reliability check) with a known sensitizer is not included in this study however a
separate study will be performed twice a year in the laboratory.
Challenge controls:
see above
Positive control substance(s):
not required
Positive control results:
A positive control (reliability check) with a known sensitizer (1-chlor-2,4-dinitro-benzol) is not included in this study however a separate study will be performed twice a year in the laboratory. The substance 1-chlor-2,4-dinitro-benzol was tested for its sensitizing effect on the skin of the guinea pig in the maximization test based an the method of Magnusson and Kligman (run during March/Aprii 1992).
Key result
Reading:
1st reading
Group:
test chemical
Dose level:
25% in olive oil DAB9
No. with + reactions:
1
Total no. in group:
20
Reading:
1st reading
Group:
negative control
Dose level:
olive oil DAB9
No. with + reactions:
0
Total no. in group:
10
Group:
positive control
Remarks on result:
other: A positive control with a known sensitizer is not included in this study however a separate study will be performed twice a year in the laboratory.

After intradermal induction well-defined erythema and slight edema were observed at the injection sites of the control and test group animals at which only Freund's adjuvant/0.9%/ aqueous NaCl-solution (1:1) was applied.

 

Injection of the test substance preparation in olive oil DAB 9 caused well-defined erythema and slight edema. Necrotic skin changes and slight edema could be observed in the test group animals after application of the test substance preparation in Freund's adjuvant/0.9%/ aqueous NaCl-solution (1:1).

 

The animals of the control groups, which were treated with olive oil DAB 9 showed very slight erythema.

 

After percutaneous induction incrustation, partially open (caused by the intradermal induction) in addition to well-defined erythema and slight edema could be observed in the control group animals. The animals of the test group showed necrotic skin changes (caused by the intradermal induction) in addition to slight edema. The number of animals with skin findings after the 1st challenge (21 days after intradermal induction) is summarized in the following table:

 

 

Challenge

25% in olive oil DAB9

Olive oil DAB 9

Control group 1

0/10

0/10

Control group 2*

no application of test substance

0/10

Test group

1/20

1/20

 

 

x/y: number of positive reactions/number of animals tested; readings 24 h after the removal of the patch

*: Control group 2 that had been intended for a potential 2nd challenge have not been treated with the test compound, since a 2nd challenge was not necessary on the basis of the unambiguous results of the 1st challenge

 

Based on the results of the study under the test conditions chosen it was concluded that N-(n-Octyl)pyrrolidone does not have a sensitizing effect on the skin of the guinea pig in the Maximization Test.

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

An in vitro or in chemico skin sensitisation study does not need to be conducted because adequate data from an in vivo skin sensitisation study are available.

In a GLP study, performed according to OECD guideline 406 (1992_RL1), after intradermal induction well-defined erythema and slight edema were observed at the injection sites of the control and test group animals. Injection of the test substance preparation in olive oil DAB 9 caused well-defined erythema and slight edema. Necrotic skin changes and slight edema could be observed in the test group animals. The animals of the control groups, which were treated with olive oil DAB 9 showed very slight erythema. After percutaneous induction incrustation, partially open (caused by the intradermal induction) in addition to well-defined erythema and slight edema could be observed in the control group animals. The animals of the test group showed necrotic skin changes (caused by the intradermal induction) in addition to slight edema. After the challenge (24 hours after the removal of the test patch) with the 25 % test substance preparation in olive oil DAB 9 well-defined erythema and very slight edema could be observed in 1 out of 20 test group animals. One of the control animals also showed slight erythema in 1/20 animals.

Based on the results of the study under the test conditions chosen and applying the evaluation criteria cited in respective endpoint study record it was concluded that N-(n-Octyl)pyrrolidone does not have a sensitizing effect on the skin of the guinea pig in the Maximization Test. The results obtained with this test are in line with the findings on the skin irritation properties of the test substance in rabbits.

Supporting results were obtained in another GMPT (GLP, OECD guideline 406, 1989_RL1).

Respiratory sensitisation

Endpoint conclusion
Additional information:

Migrated from Short description of key information:
Actually, there is no information available.

Justification for classification or non-classification

Based on the test result of the Guinea Pig Maximization Test and according to Annex I of 1272/2008, there is no need to classify the test substance as skin sensitizing.