2,2'-[ethylenebis(oxymethylene)]bisoxirane

Endpoint summary

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)

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Study conducted in the Republic of Korea.

Species:

guinea pig

Strain:

Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at the start of treatment: main study: 7 weeks
- Weight at the start of treatment: main study: 409-494 g
- Housing:
quarantine-acclimation period: polycarbonate cages (for 4 days after receipt) and stainless wire mesh cages
study: stainless wire mesh cages
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: during the acclimation period, animals were observed for clinical signs once daily for 19 days (preliminary study: 5 days).

ENVIRONMENTAL CONDITIONS
- Temperature (°C): measurement value: 20.2–23.3°C, permissible range: 18.0–24.0°C
- Humidity (%): measurement value: 39.5–56.8%, permissible range: 30.0–70.0%
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Route:

intradermal

Vehicle:

water

Concentration / amount:

12.5%

Route:

epicutaneous, occlusive

Vehicle:

water

Concentration / amount:

6.25%

Day(s)/duration:

2

Route:

epicutaneous, occlusive

Vehicle:

water

Concentration / amount:

3.13%

Day(s)/duration:

1

No. of animals per dose:

test substance group: 20
control group: 10

Positive control substance(s):

no

Positive control results:

A positive control group was not set in this study. However, for the validity of the study, a positive control study was conducted periodically using CDNB (1-Chloro-2,4-dinitrobenzene) which is a positive substance in the Maximization Test method.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

12.5%

No. with + reactions:

6

Total no. in group:

20

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

12.5%

No. with + reactions:

9

Total no. in group:

20

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

0.1%

No. with + reactions:

10

Total no. in group:

10

Remarks on result:

other: Not concurrent with study but conducted periodically

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

0.1%

No. with + reactions:

10

Total no. in group:

10

Remarks on result:

other: Not concurrent with study but conducted periodically

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

10

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

10

Dose selection for the 1st induction (intradermal):

In the preliminary study, the 2 treated animals were dead the day after intradermal induction. In these 2 animals necrosis was confirmed at 100% test substance, but skin reactions such as redness and swelling could not be observed at 50, 25, 12.5, 6.25 and 3.13% test substance. Therefore, an additional preliminary study was performed. The shoulder regions of 5 guinea pigs were clipped using electric clippers and shaved off hair using an electric shaver. Each animal was injected intradermally with 0.1 mL of the test substance at dose levels of 50, 25, 12.5, 6.25, and 3.13%.

As a result of the additional preliminary study, intense redness (score 3) with skin necrosis was observed in both animals at 50 and 25% test substances at 24 and 48 h after intradermal injection. Intense redness (score 3) was observed in both animals at 12.5 and 6.25% test substances. Redness (score 2) was observed in both animals at 3.13% test substance at 24 h after intradermal injection, and intense redness (score 3) was observed at 48 h.

In accordance with the results of the preliminary and additional preliminary studies, the dose level for the 1st induction was the highest concentration of the test

substance at which necrosis was not confirmed at the intradermal injection sites. Therefore, the dose level was selected at 12.5% test substance.

Dose selection for the 2nd induction (epicutaneous):

The dose level for the 2nd induction was the highest concentration of the test substance at which mild to moderate skin reactions were confirmed at the topical application sites. Therefore, the dose level was selected at 6.25% test substance.

Dose selection for the challenge:

The challenge dose level was selected at 3.13% test substance, the highest concentration at which skin reaction was not confirmed at the topical application sites.

Interpretation of results:

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

Executive summary:

This study was conducted to evaluate the skin sensitization potential of the test substance,

2,2’-[ethylenebis(oxymethylene)]bisoxirane, by Maximization Test using Hartley guinea pigs.

Test groups consisted of a test substance group (20 animals) and a control

group (10 animals). Since skin reactions were observed at the topical application sites in the

preliminary study, the induction sites of each group were not pretreated with 10% sodium

dodecyl sulfate (SDS) prior to the second induction.

Based on the result of this study, the sensitization rate of the test substance, 2,2’-

[ethylenebis(oxymethylene)]bisoxirane, was 45% and the sensitization grade was ‘Moderate’.

Therefore, it was judged that skin sensitization was produced under the conditions of this study.

In the test substance group, the 12.5% test substance was injected intradermally for the first

induction. The second induction was conducted with the 6.25% test substance occluded for 48

hours. The challenge was conducted with the 3.13% test substance and water for injection

(WFI) occluded for 24 hours. As a result, the redness (score 1-2) was observed at 3.13% test

substance challenge sites in six of twenty at 24 hours after challenge patch removal. Redness

(score 1-2) was observed in nine of twenty animals at 48 hours. The challenge sites with WFI

did not reveal any evidence of adverse skin reactions such as redness and swelling in any

animal.

In the control group, the first and second inductions with WFI, and the challenges with the

3.13% test substance and WFI were conducted. As a result of the challenge, no skin reactions

were observed in any animal.

During the observation period, no abnormality in clinical signs or body weight gain was

observed in any animal of any group.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The substance was tested in a Guinea pig maximisation test. The sensitization rate with an intradermal induction dose of 12.5% was 45%. A substance with a sensitization rate ≥ 30% and intradermal induction > 1% is classified Skin Sens. 1B.