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Description of key information

 

It was observed that the test chemical failed to induce contact sensitization at challenge concentration of 3% in the test animals. Thus, the test chemical was considered to be not sensitizing on skin of guinea pigs at concentration of 3% in an Open Epicutaneous Test (OET).

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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data is from publication
Qualifier:
according to
Guideline:
other: Open Epicutaneous test
Principles of method if other than guideline:
An Open Epicutaneous Test (OET) was performed on guinea pigs to assess the skin sensitization potential of the test chemical
GLP compliance:
not specified
Type of study:
open epicutaneous test
Justification for non-LLNA method:
Currently no LLNA study is available for assessment. The Guinea Pig Maximization Test (GPMT) has been carried out as an animal test to predict human sensitization for over a decade and is recommended by international test guidelines such as OECD.
Specific details on test material used for the study:
- Name of test material (as cited in study report): Methyl N-methyl anthranilate
- Molecular formula : C9H11NO2
- Molecular weight : 165.191 g/mole
- Substance type: Organic
- Physical State: Liquid

Species:
guinea pig
Strain:
other: Himalayan white-spotted
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Institute Of Biomedical Research Fullinsdrof Switzerland
- Age at study initiation:
- Weight at study initiation: 400 to 500 g.
- Housing:
- Diet (e.g. ad libitum): supplemented with green,Vegetables, carrots and vitamin C ad libitum
- Water (e.g. ad libitum): ad libitum
Route:
epicutaneous, open
Vehicle:
other: ethanol, acetone, H20, petroleum, PEG and/or other suitable vehicles
Concentration / amount:
Concentration:100%, 30%, 10%, 3%, 1%, or 0.3%
Amount: 0.1ml
Day(s)/duration:
3 weeks
Adequacy of induction:
not specified
No.:
#1
Route:
epicutaneous, open
Vehicle:
other: ethanol, acetone, H20, petroleum, PEG and/or other suitable vehicles
Concentration / amount:
Concentration:3%
Amount: 0.025ml
Day(s)/duration:
on days 21 and 35
Adequacy of challenge:
not specified
No. of animals per dose:
6-8 guinea pigs
Details on study design:
RANGE FINDING TESTS: The minimal irritating concentration of each material is used to confirm the biological activity determined before starting the induction. These tests are performed by applying with a pipette 0.025 ml of each concentration to skin areas measuring 2 cm2. The reactions are read after 24, 48 and/or 72h.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 21
- Exposure period:24 hours
- Test groups:6-8 guinea pigs
- Control group:3 guinea pigs
- Site: an area measuring 8 cm2 on the clipped flank skin of the guinea pigs
- Frequency of applications: The applications are repeated daily for 3 weeks or done 5 times weekly during 4 weeks
- Duration: 21 days (3 weeks)
- Concentrations: 100%, 30%, 10%, 3%, 1%, or 0.3% in vehicle.
Amount: 0.1ml

B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day(s) of challenge: on days 21 and 35
- Exposure period:24 hours
- Test groups: 6-8 guinea pigs
- Control group: 3 guinea pigs
- Site: contralateral flank measuring 2 cm2
- Concentrations: Concentration:6%
Amount: 0.025ml
- Evaluation (hr after challenge): 24,48 and/or 72h.
Challenge controls:
The 10 controls were either left untreated or treated with 0.1 ml aliquot of the vehicle for 21 days
Positive control substance(s):
not specified
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
3%
No. with + reactions:
0
Total no. in group:
8
Clinical observations:
It was observed that none of the guinea pigs induced contact sensitization at challenge concentration of 3%.
Remarks on result:
no indication of skin sensitisation

Table: Allergenicity of Compounds tested in Humans by the Maximization Test and in Guinea Pigs by 4 Different Procedures

Guinea pigs

OET

DTb

MTb

FCATb

Minimum irritating concentration

(%)

Results

Results

Results

Results

After 1 day application

After 21 days application

100

3

-

-

-

-

a- the occlusive eliciting concentration application was only at the user concentration *2              

b- DT, MT, FCAT: Concentrations see in the method

 

Interpretation of results:
other: not sensitizing
Conclusions:
It was observed that the test chemical failed to induce contact sensitization at challenge concentration of 3% in the test animals. Thus, the test chemical was considered to be not sensitizing on skin of guinea pigs at concentration of 3% in an Open Epicutaneous Test (OET).
Executive summary:

An Open Epicutaneous Test (OET) was performed on guinea pigs to assess the skin sensitization potential of the test chemical.

 

On day 1 during induction, 0.1 ml of the test chemical was applied at concentrations of 100%, 30%, 10%, 3%, 1%, or 0.3% in vehicle to an area measuring 8 cm2 on the clipped flank skin of the guinea pigs. The applications are repeated daily for 3 weeks or done 5 times weekly during 4 weeks, usually on the same skin sites. The application sites were left uncovered and the reactions, if continuous daily applications were performed, can be read 24 h after each application, or at the end of each week.

 

To determine whether or not contact sensitization was induced, all groups of guinea pigs previously treated for 21 days, as well as 10 untreated, or only pretreated with the vehicle, controls are tested on days 21 and 35 on the contralateral flank with the test material. This test was performed by applying with a pipette 0.025 ml of each concentration to skin areas measuring 2 cm2. The reactions were read after 24, 48 and/or 72h.

 

It was observed that the test chemical failed to induce contact sensitization at challenge concentration of 3% in the test animals. Thus, the test chemical was considered to be not sensitizing on skin of guinea pigs at concentration of 3% in an Open Epicutaneous Test (OET).

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Skin Sensitization

Various studies have been summarized to determine the allergenic potential of the test chemical in living organisms.The studies are based on in vivo experiments in guinea pigs as well as humans for the test chemical.

An Open Epicutaneous Test (OET) was performed on guinea pigs to assess the skin sensitization potential of the test chemical.

On day 1 during induction, 0.1 ml of the test chemical was applied at concentrations of 100%, 30%, 10%, 3%, 1%, or 0.3% in vehicle to an area measuring 8 cm2 on the clipped flank skin of the guinea pigs. The applications are repeated daily for 3 weeks or done 5 times weekly during 4 weeks, usually on the same skin sites. The application sites were left uncovered and the reactions, if continuous daily applications were performed, can be read 24 h after each application, or at the end of each week. 

To determine whether or not contact sensitization was induced, all groups of guinea pigs previously treated for 21 days, as well as 10 untreated, or only pretreated with the vehicle, controls are tested on days 21 and 35 on the contralateral flank with the test material. This test was performed by applying with a pipette 0.025 ml of each concentration to skin areas measuring 2 cm2. The reactions were read after 24, 48 and/or 72h.

It was observed that the test chemical failed to induce contact sensitization at challenge concentration of 3% in the test animals. Thus, the test chemical was considered to be not sensitizing on skin of guinea pigs at concentration of 3% in an Open Epicutaneous Test (OET).

This is supported by the sensitization study performed on 25 volunteers to determine its sensitization potential.   10% in petrolatum of test sample was administrated on different panels of human subject.   No known cutaneous reaction was observed in 25 volunteers. Therefore, the test chemical can be considered as not sensitizing on human skin.

These results are lent support by the study performed on guinea pigs according to Draize method to determine the sensitization potential of the test chemical. Groups of 6–8 male and female outbred Himalayan white-spotted guinea pigs were used for the study. A dose of 0.05 ml of 0.1% solution of test chemical in isotonic saline was injected intradermally on day 0 and further doses of 0.1 ml each were injected on 9 alternate days. The total dose injected was 0.95 mg. The treated animals and untreated controls were challenged intradermally with 0.05 ml of a 0.1 per cent solution on days 35 and 49.The evaluation criterion was the mean diameter of the papular reactions at the test sites.

No sensitization reactions were observed on the skin of guinea pigs. Hence, the test chemical was considered to be not sensitizing to skin.

These results are further supported by a Guinea pig Maximization test performed to assess the sensitization potential of the test chemical in guinea pigs. Groups of 6–8 male and female outbred Himalayan white-spotted guinea pigs were used for the study. On day 0, the animals were injected intradermally with 0.1 ml of a 5% solution of test chemical, 0.1 ml of a 5% emulsion of test chemical in Freund’s complete adjuvant (FCA) and 0.1 ml of FCA alone. Each injection was given twice. In addition, 250 mg of test chemical dissolved in petrolatum at a concentration of 25% was applied on day 8 to a clipped area of the neck and was kept under occlusive bandage for 48 h. On day 21, test chemical at a sub-irritant concentration in petrolatum was applied to the flank for 24 h under occlusion. Reactions were read at 24 and 48 h after removal of the patch.

No sensitization reactions were observed on the skin of guinea pigs.

Hence, the test chemical was considered to be not sensitizing to skin.

These results are also supported by a Freund’s Complete Adjuvant test performed to assess the sensitization potential of the test chemical in guinea pigs. Groups of 6–8 male and female outbred Himalayan white-spotted guinea pigs were used for the study. Doses of 0.05 ml of the undiluted compound mixed with the same volume of FCA were injected intradermally into the neck on days 0, 2, 4, 7, and 9 (total dose 250 mg). The control animals were similarly treated with 5 x 0.05 ml of FCA alone. All the animals were tested epicutaneously on days 21 and 35. No sensitization reactions were observed on the skin of guinea pigs.

Hence, the test chemical was considered to be not sensitizing to skin.

The above results are also supported by another Human maximization test carried out with 10% test chemical in petrolatum on various panels of volunteers. Application was under occlusion to the same site on the forearms or backs of all subjects for five alternate day, 48-hour periods. Patch sites were pre-treated for 24 hours with 5% aqueous sodium lauryl sulfate (SLS) under occlusion. Following a 10 – 14 day rest period, challenge patches were applied under occlusion to fresh sites for 48 hours. Reactions were read at patch removal and again at 24 hours.

The test chemical failed to induce any dermal reactions after the challenge exposure.

Hence, it was assessed to be non sensitizing to the skin of humans.

Available studies for the test chemical indicate that it lacks the potential to cause any dermal reaction to the skin. Hence, it can be considered to be not sensitizing to skin.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Available studies for the test chemical indicate that it lacks the potential to cause any dermal reaction to the skin. Hence, it can be considered to be not sensitizing to skin.