Propane, 1,1,1,3,3-pentafluoro-3-methoxy-2-(trifluoromethyl)-

Endpoint summary

Description of key information

A skin sensitisation study conducted according to the Buehler method is reported.
2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane meets the criteria to be classified as Skin Sensitizer of Sub-category 1B.

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 January 2005 to 31 March 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline-conform study under GLP without deviations.

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

Buehler test

Justification for non-LLNA method:

The Buehler test was conducted prior to the change in Regulation and data requirements.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

INDUCTION: 100% (undiluted)

Day(s)/duration:

1 patch/week for 3 weeks

Adequacy of induction:

highest technically applicable concentration used

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

polyethylene glycol

Concentration / amount:

CHALLENGE: 5% in Polyethylene glycol

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

20 test animals + 10 control animals

Details on study design:

RANGE FINDING TESTS:
Irritation Screen I: 4 concentrations were tested: 100%, and 75%, 50%, 25% (w/w) diluted in PEG300
Irritation screen II: 4 concentrations were tested: 15%, 10%, 5% and 3% (w/w) in PEG300

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 1 patch/week over 3 weeks (3 exposures)
- Exposure period: 1 application per week, for 6 hrs
- Test groups: 20 males
- Control group: 10 males
- Site: 25 mm Hill Top chamber applied on the left shoulder of each test animal
- Frequency of applications: once a week
- Duration: 3 weeks
- Concentrations: undiluted substance

B. CHALLENGE EXPOSURE
- No. of exposures: one application
- Day(s) of challenge: 2
- Exposure period: 6 hrs
- Test groups: 20 males
- Control group: 10 males
- Site: left posterior quadrant of the side and back of the animals
- Concentrations: 5% in PEG 300
- Evaluation (hr after challenge): 24 and 48 hrs

Challenge controls:

Ten animals of the control group were not treated during the induction and were challenged with the test substance at 5% in PEG 300.

Positive control substance(s):

yes

Remarks:

5% alpha-Hexylcinnamaldehyde, in a separate run within 6 month prior

Positive control results:

1st challenge: 3% negative
2nd challenge: 5% => 7/20 positive responses at 24h and 11/20 positive responses at 48h

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

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

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:

test chemical

Dose level:

5% in PEG 300

No. with + reactions:

7

Total no. in group:

19

Clinical observations:

One animal was found dead on test day 25. No clinical signs were observed on the other animals

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5% in PEG 300

No. with + reactions:

6

Total no. in group:

19

Clinical observations:

No clinical effects observed

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

5% alpha-Hexylcinnamaldehyde in PEG 300

No. with + reactions:

7

Total no. in group:

20

Remarks on result:

positive indication of skin sensitisation

Remarks:

Re-challenge at a slightly higher concentration

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

5% alpha-Hexylcinnamaldehyde in PEG 300

No. with + reactions:

11

Total no. in group:

20

Remarks on result:

positive indication of skin sensitisation

Remarks:

Re-challenge at a slightly higher concentration

ERYTHEMA SCORE	TEST GROUPS		CONTROL GROUP
	20 animals		10 animals
	24 hrs	48 hrs	24 hrs	48 hrs
1	12	13	10	10
2	7	6	0	0
3	0	0	0	0
4	0	0	0	0
No. with grades >= 1	0	0	0	0
No. tested	19	19	10	10
INCIDENCE*	7/19 ***		0/10
SEVERITY**	0.3 - 0.4		0
* number of animals showing a response of grade 1 or greater at either 24- or 48- hour reading out of the total animals.
** Total sum of 24- and 48-hours response readings divided by the number of animals exposed (maximum of 3).
*** One animal of the test group was found dead on day 25 (i.e. 10 days after the last induction). At necropsy, congestion in the lung was noted. The death may be related to the test item treatment, however, the single incidence in one of the 20 tested animals, may also be regarded as spontaneous and treatment unrelated.

Grading of animals was done by positioning each animal under true light.

The grading method used for irritation screens, induction and challenge was identical.

The scoring system was performed by visual assessment of erythema, oedema and other clinical changed in skin conditions. They were assessed as following:

0	no visible change
1	discrete or patchy erythema
2	moderate or confluent erythema
3	intense erythema and swelling

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane meets the Regulation EC No. 1272/08 classification criteria for Skin Sensitisation Sub-Category 1B.

Executive summary:

The purpose of the study was to assess the possible allergenic potential of 2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane when administered topically to Albino Dunkin Hartley guinea pigs. For this purpose the "Buehler test" was used.

Twenty male animals of the test group were treated topically with 2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane at 100% once a week for a 3 -week induction phase. Two weeks after the final induction application the animals were challenged with the test item concentration of 5% in Polyethylene glycol (PEG) 300. The ten animals of the control group were not treated during the induction. They were treated once at challenge with 2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane at 5% in PEG 300.

After challenge treatment, 37% (at the 24 -hour reading) and 32% (at the 48 -hours reading) of the animals of the test group were observed with skin reactions. No skin reactions were observed in the control group treated in the same conditions during the challenge phase.

According to Regulation (EU) No. 1272/08, a substance has to be classified as skin sensitizer if a response of at least 15 % of the animals in a non-adjuvant guinea pig test method is observed. Furthermore, in accordance to the second adaptation to technical progress for the CLP Regulation, if in the Buehler test there is a positive response between 15 % and 60 % responding at > 0,2 % to ≤ 20 % topical induction dose or a positive response ≥ 15 % at > 20 % topical induction dose the substance has to be classified as Skin Sensitizer Sub-Category 1B.

2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane meets the above reported classification criteria and therefore it needs to be classified as skin sensitizer Sub-Category 1B.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

A skin sensitisation study conducted according to the Buehler method is reported. The study was conducted under GLP and according to recognized international test guidelines.

Under the test a positive response in test animals was observed. The classification criteria of Regulation EC No. 1272/08 and Regulation (EU) No. 286/2011 (CLP second adaptation to technical and scientific progress) were applied.

2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane meets the classification criteria to be classified as Skin Sensitizer of sub-category 1B.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

According to Regulation (EU) No. 1272/08, a substance has to be classified as skin sensitizer if a response of at least 15 % of the animals in a non-adjuvant guinea pig test method is observed.

Furthermore, in accordance to Regulation (EU) No. 286/2011 (CLP second adaptation to technical progress), if in the Buehler test there is a positive response between 15% and 60% responding at > 0,2% to ≤ 20% topical induction dose or a positive response ≥ 15 % responding at > 20 % topical induction dose, the substance has to be classified as Skin Sensitizer Sub-Category 1B.

2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane was tested with an induction dose of 100% (undiluted substance) and the positive response observed at the challenge was the following:

- 37% (at the 24 -hour reading)

- 32% (at the 48 -hours reading)

Consequently 2-[difluoro(methoxy)methyl]-1,1,1,3,3,3-hexafluoropropane meets the classification criteria of Regulation (EU) No. 1272/08 and Regulation (EU) No. 286/2011 and it needs to be classified as Skin Sensitizer of Sub-category 1B.