2,4,6-trimethyl-2,4,6-tris(3,3,3-trifluoropropyl)cyclotrisiloxane

Endpoint summary

Description of key information

In the key skin sensitisation study for 2,4,6-trimethyl-2,4,6-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, conducted according to OECD Test Guideline 406 and in compliance with GLP, the registered substance was concluded to be not sensitising to skin when tested in guinea pigs (BSL Bioservice, 2013c).

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:

21st November 2012 to 1st February 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

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:

Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River
- Age at study initiation: 4-6 weeks
- Weight at study initiation: 364-440g
- Housing: In groups in Terluran cages
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: At least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ±3
- Humidity (%): 55 ±10
- Air changes (per hr): At least 10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 27-11-2012 To: 01-02-2013

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

0.5g of 100% test substance

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

0.5g of 100% test substance

No. of animals per dose:

Test group: 20
Negative control group: 10

Details on study design:

RANGE FINDING TESTS: Two animals were treated topically with concentrations of 50% and 100% of the test substance (suspended in vaseline) for six hours. A dry patch served as a negative control. Based on the results of this preliminary test a concentration of 100% was chosen for the induction and challenge phases of the main study.

MAIN STUDY
A. INDUCTION EXPOSURE
The left flank was cleared of hair, by close clipping, prior to the first application and again prior to further applications.

The test substance was loaded with 0.5g of the test substance. The patch was applied to the test area of approximately 2.5 x 2.5cm and was held in place by an occlusive dressing for six hours. The procedure was repeated once per week at the same test area at weekly intervals for a total of three weeks. In the negative control group, a dry gauze patch was applied to the test area under the same conditions as the test group.

B. CHALLENGE EXPOSURE
Both flanks were cleared of hair, by close clipping, prior to the challenge application.

13 days after the last induction application the test substance was applied to an area of approximately 2.5 x 2.5cm on the right flank and was held in contact with an occlusive dressing for six hours. A dry gauze patch was applied to an area of approximately 2.5 x 2.5cm on the left flank (intraspecies control) and was held in contact with an occlusive dressing for six hours.

Approximately 21 hours after removing the patch, the challenge area was cleaned and cleared of hair by the use of a depilatory cream. Approximately 24 and 48 hours after removing the patch the skin reaction was observed and recorded. Additionally, all animals were observed for signs of toxicity at least once daily during the test period.

Challenge controls:

Dry patch

Positive control substance(s):

yes

Remarks:

mercaptobenzothiazole

Positive control results:

The sensitisation rate after application of the positive-control substance (25% in vaseline) was 20% confirming the reliability of the test system.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

100%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

Dry patch

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

Dry patch

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

25% in vaseline

No. with + reactions:

4

Total no. in group:

20

Remarks on result:

other: The sensitisation rate after application of the positive-control substance (25% in vaseline) was 20% confirming the reliability of the test system.

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

25% in vaseline

No. with + reactions:

4

Total no. in group:

20

Remarks on result:

other: The sensitisation rate after application of the positive-control substance (25% in vaseline) was 20% confirming the reliability of the test system.

The body weight gains of all animals were normal, when compared with the historical data.

Interpretation of results:

GHS criteria not met

Conclusions:

In a skin sensitisation study (Buehler study) conducted to OECD 406 and to GLP (reliability score 1) 2,4,6-trimethyl-2,4,6-tris(3,3,3-trifluoropropyl)cyclotrisiloxane did not cause a positive reaction in any of the guinea pigs tested, and therefore under the conditions of this study is not a skin sensitizer.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

In the key skin sensitisation study for 2,4,6-trimethyl-2,4,6-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, conducted according to OECD Test Guideline 406 and in compliance with GLP, the registered substance was concluded to be not sensitising to skin when tested in guinea pigs  (BSL Bioservice, 2013c).

At induction, 0.5 g of the test substance was applied onto the left flank (cleared of hair) of each guinea pig and kept in place under occlusive dressing for 6 hours. The procedure was repeated once per week at the same test area at weekly intervals for a total of three weeks. A dry gauze patch was applied to the test area for the negative control group under the same conditions as the test group.

At challenge, approximately 13 days after the last induction 0.5 g of the test substance was applied onto the right flank (cleared of hair) of each guinea pig and kept in place under occlusive dressing for 6 hours. A dry gauze patch was applied to the test area for the negative control group under the same conditions as the test group. The skin reactions were observed and recorded at 24 and 48 hours after removal of the patch. Additionally, all animals were observed for signs of toxicity at least once daily during the test period.

2,4,6-Trimethyl-2,4,6-tris(3,3,3-trifluoropropyl)cyclotrisiloxane did not cause a positive reaction in any of the guinea pigs tested. The negative and positive control (mercaptobenzothiazole) gave appropriate results.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the skin sensitisation study, 2,4,6-trimethyl-2,4,6-tris(3,3,3-trifluoropropyl)cyclotrisiloxane is not classified for skin sensitisation in accordance with Regulation (EC) No 1272/2008.