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Description of key information

In the key skin sensitisation study, conducted according to OECD TG 406 and in compliance with GLP, the test material was concluded to be not sensitising to skin (Eurofins, 2018).

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
Study period:
19 June 2018 to 19 July 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
Buehler test
Justification for non-LLNA method:
An LLNA study was not performed because the test method is not considered to be suitable for substances that contain silicon. Please refer to the attached document for further details.
Species:
guinea pig
Strain:
other: Crl: HA - Guinea Pigs
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River, 97633 Sulzfeld, German
- Females (if applicable) nulliparous and non-pregnant: n/a
- Microbiological status of animals, when known: The animals were derived from a controlled full-barrier maintained breeding system.
- Age at study initiation: approximately 5–6 weeks old
- Weight at study initiation: 328–383 g
- Housing: The animals were kept in groups in Terluran - cages on Altromin saw fibre bedding
- Diet (e.g. ad libitum): Free access to autoclaved hay and to Altromin 3122 maintenance diet for guinea pigs, rich in crude fibre, ad libitum.
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: at least 5 days
- Indication of any skin lesions: not specified

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3°C
- Humidity (%): 55 +/- 10%
- Air changes (per hr): at least 10 x / hour
- Photoperiod (hrs dark / hrs light): 12 hours light, 12 hours dark
Route:
epicutaneous, occlusive
Vehicle:
cotton seed oil
Concentration / amount:
0.1%
Day(s)/duration:
6 hours once a week for three weeks
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
cotton seed oil
Concentration / amount:
0.006%
Day(s)/duration:
6 hours
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
Number of animals in the preliminary test: 12
Number of animals in the test group: 20
Number of animals in the negative-control group: 10
Details on study design:
RANGE FINDING TESTS: Before the initiation of the preliminary test, a solubility test was performed to define the maximum concentration which is technically applicable to the animals. Solubility was found for the vehicle dried cottonseed oil at a concentration of 95%. Adequate concentrations for the inductions and the challenge were determined by a preliminary test with different concentrations. Each concentration of the test item (emulsified with dried cottonseed oil) was applied topically to the flanks of the animals using occlusive dressings. The following concentrations were tested:

1 animal was treated topically with concentrations of 100% and 75% of the test item for 6 hours.
1 animal was treated topically with concentrations of 90% and 95% of the test item for 6 hours.
1 animal was treated topically with concentrations of 80% and 85% of the test item for 6 hours.
1 animal was treated topically with a concentration of 75% of the test item on both flanks for 6 hours.
1 animal was treated topically with concentrations of 50% and 60% of the test item for 6 hours.
1 animal was treated topically with concentrations of 30% and 40% of the test item for 6 hours.
1 animal was treated topically with concentrations of 20% and 10% of the test item for 6 hours.
1 animal was treated topically with concentrations of 2.5% and 1% of the test item for 6 hours.
1 animal was treated topically with concentrations of 0.5 and 0.25% of the test item on one flank and with concentrations of 0.1 and 0.05% of the test item on the other flank for 6 hours.
1 animal was treated topically with concentrations of 0.05% and 0.025% of the test item for 6 hours.
1 animal was treated topically with concentrations of 0.0125% and 0.006% of the test item for 6 hours.
1 animal was treated topically with a concentration of 0.006% of the test item on both flanks for 6 hours.

Based on the results of this preliminary test the following concentrations were chosen for the main test:
a concentration of 0.1% for the dermal inductions
a concentration of 0.006% for the challenge application


MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: three
- Exposure period: 6 hours once a week
- Test groups: test and negative control groups
- Control group: yes
- Site: left flank
- Frequency of applications: once a week for three consecutive weeks
- Duration: 6 hours
- Concentrations: 0.1% in cotton seed oil

B. CHALLENGE EXPOSURE
- No. of exposures: one
- Day(s) of challenge: one
- Exposure period: 14 days after the last induction
- Test groups: test and negative control groups
- Control group: yes
- Site: Both flanks
- Concentrations: 0.006% in cotton seed oil
- Evaluation (hr after challenge): at 24 and 48 hours
Challenge controls:
A patch loaded with 0.5 mL of the vehicle was applied to an area of approximately 2.5 x 2.5 cm on the left flank at an untreated site (intraspecific control) and was held in contact with the help of an occlusive dressing for 6 hours.
Positive control substance(s):
yes
Remarks:
mercaptobenzothiazole
Positive control results:
The sensitisation rate after application of the positive-control substance mercaptobenzothiazole (25% in Vaseline) was 50%, confirming the reliability of the test system.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.006% in cotton seed oil
No. with + reactions:
2
Total no. in group:
20
Clinical observations:
Erythema grade 1
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
0.006% in cotton seed oil
No. with + reactions:
2
Total no. in group:
20
Clinical observations:
Erythema grade 1
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
cotton seed oil
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
cotton seed oil
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
mercaptobenzothiazole (25% in Vaseline)
Remarks on result:
other: The sensitisation rate after application of the positive-control substance mercaptobenzothiazole (25% in Vaseline) was 50%, confirming the reliability of the test system.
Interpretation of results:
GHS criteria not met
Conclusions:
In the skin sensitisation study, conducted according to OECD TG 406 and in compliance with GLP, the test material caused positive reactions identified as sensitisation at the tested concentration in 10% of the test animals that were identified as sensitisation at the tested concentration. Therefore, the substance is not considered to be a sensitizer.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

The key skin sensitisation study was conducted according to OECD TG 406 and in compliance with GLP (Eurofins, 2018). Before the initiation of the preliminary test, a solubility test was performed to define the maximum concentration which is technically applicable to the animals. Solubility was found for the vehicle dried cottonseed oil at a concentration of 95%. The adequate concentrations for the inductions and the challenge were determined by a preliminary test with different concentrations. Based on the results of this preliminary test the following concentrations were chosen for the main test: a concentration of 0.1% for the dermal inductions and a concentration of 0.006% for the challenge application.

At induction, the left flank was cleared of hair (close-clipped) prior to the first application and again prior to further applications. A gauze patch was loaded with 0.5 mL of the prepared test substance or the vehicle. The patch was applied to the test area of approximately 2.5 x 2.5 cm and was held in contact with the help of an occlusive dressing for 6 hours. This procedure was repeated once a week at the same test area at weekly intervals for 3 weeks.

At challenge, both flanks were cleared of hair (close-clipped) prior to the challenge application. 14 days after the last induction application 0.5 mL of the prepared test substance was applied to an area of approximately 2.5 x 2.5 cm on the right flank and was held in contact with the help of an occlusive dressing for 6 hours. A patch loaded with 0.5 mL of the vehicle was applied to an area of approximately 2.5 x 2.5 cm on the left flank at an untreated site (intraspecific control) and was held in contact with the help of an occlusive dressing for 6 hours.

The results of the test animals at the challenge phase were compared to the results of the control animals.

No oedema was observed in any animal at any time of observation. Erythema grade 1 was observed in 2 test group animals out of 20 at the 24 and 48 hours observations after challenge. No findings were observed after challenge exposure in any of the control animals. The sensitisation rate after application of the positive-control substance mercaptobenzothiazole (25% in Vaseline) was 50%, confirming the reliability of the test system. In conclusion there was evidence of sensitisation and the percentage of sensitised animals was 10%. Based on these findings, the test material was concluded to be not sensitising to skin according to the criteria specified in Regulation (EC) NO. 1272/2008.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the available data, no classification for skin sensitisation is required for the submission substance according to Regulation (EC) No. 1272/2008.