Isooctene

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:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant, guideline study, available as unpublished report, no restrictions, fully adequate for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall, Darley Oaks, Newchurch, Burton on Trent, Staffordshire, England
- Age at study initiation: 6-8 weeks old
- Weight at study initiation: 329-394 g (males); 303-372 g (females)
- Housing: No more than 5/sex/cage in stainless steel cages
- Diet: Guinea pig FDI (Special Diets Services Limited, Witham, Essex, England) ad libitum
- Water: Tap water ad libitum
- Acclimatisation period: between 6-16 days

ENVIRONMENTAL CONDITIONS
- Temperature: 19-24°C
- Humidity: 41-74%
- Air changes: 10 per hour
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 3 June 1996 To: 4 July 1996

Route:

intradermal and epicutaneous

Vehicle:

paraffin oil

Concentration / amount:

50% v/v for intradermal injections and 100% (as supplied) for epicutaneous application

Route:

epicutaneous, occlusive

Vehicle:

paraffin oil

Concentration / amount:

50% v/v for intradermal injections and 100% (as supplied) for epicutaneous application

No. of animals per dose:

10/sex (test group) 5/sex (negative control group)

Details on study design:

RANGE FINDING TESTS: A primary skin irritation screen was used to determine the concentration of test material used during the main study. The maximum practicable concentration of the test material in the chosen vehicle was taken as 50% v/v for injection administration and as supplied (100%) for topical applications.

MAIN STUDY
A. INDUCTION EXPOSURE
Three pairs of intradermal injections of Freunds Complete Adjuvant, 50% v/v 2,4,4-trimethyl pentene in paraffin oil and 50% v/v 2,4,4,-trimethyl pentene in the adjuvant were made on Day 1.
Seven days later the same area of skin was treated by topical application of 2,4,4-trimethyl pentene as supplied and the test site was covered by an occlusive dressing for 48 hours.

The same induction procedures were carried out on a contemporaneous control group of five male and five female animals, except that the test material was replaced by vehicle in all doses.

B. CHALLENGE EXPOSURE
On Day 22, all animals were challenged by occluded application of paraffin oil to the left flank and 75% and 30% v/v 2,4,4-trimethyl pentene in paraffin oil to two sites on the right flank. The occlusive dressings were removed on the following day and the condition of the test sites was assessed approximately 24 and 48 hours later.

Challenge controls:

The same induction procedures were carried out on a contemporaneous control group of five male and five female animals, except that the test material was replaced by vehicle in all doses.
Challenge was identical as for test animals.

Positive control substance(s):

not specified

Statistics:

Not applicable

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

75%

No. with + reactions:

6

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 75%. No with. + reactions: 6.0. Total no. in groups: 20.0.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

75 %

No. with + reactions:

9

Total no. in group:

20

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 75 %. No with. + reactions: 9.0. Total no. in groups: 20.0.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

75%

No. with + reactions:

1

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 75%. No with. + reactions: 1.0. Total no. in groups: 10.0.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

75%

No. with + reactions:

3

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 75%. No with. + reactions: 3.0. Total no. in groups: 10.0.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

30%

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 30%. No with. + reactions: 0.0. Total no. in groups: 20.0.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

30%

No. with + reactions:

3

Total no. in group:

20

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 30%. No with. + reactions: 3.0. Total no. in groups: 20.0.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

30%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 30%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

30%

No. with + reactions:

1

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 30%. No with. + reactions: 1.0. Total no. in groups: 10.0.

Intradermal injection of 50% v/v 2,4,4-trimethyl pentene in adjuvant gave rise to moderate erythema, pallor and eschar formation; no dermal reaction resulted from a similar administration of 50% v/v 2,4,4-trimethyl pentene in paraffin oil.

Occluded topical application of 2,4,4-trimethyl pentene as supplied caused slight erythema and exfoliation.

 

Challenge application of 75% v/v 2,4,4-trimethyl pentene in paraffin oil gave rise to a positive response (slight erythema or a more marked reaction) in nine test and three control animals.

 

Challenge application of 30% v/v 2,4,4-trimethyl pentene in paraffin oil caused a positive response in three test animals and one control animal.

 

Challenge application of paraffin oil alone caused a positive response in four test animals.

 

A significant response (a reaction more severe than the most marked amongst the controls) was evident in three test animals following challenge application of 75% v/v 2,4,4-trimethyl pentene in paraffin oil and in no test animals following challenge application of the 30% formulation.

 

It was concluded that, under the conditions of this study, repeated administration of 2,4,4-trimethyl pentene had, at most, a low potential to cause delayed contact hypersensitivity in guinea-pigs. The incidence of significant response was below the EEC limit value (30%) to classify the test material as a dermal sensitizer.

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

Repeated administration of 2,4,4-trimethyl pentene had, at most, a low potential to cause delayed contact hypersensitivity in guinea-pigs. It does not require classification as a dermal sensitiser according to the EU classification system.

Executive summary:

Under the conditions of this study, repeated administration of 2,4,4-trimethyl pentene had, at most, a low potential to cause delayed contact hypersensitivity in guinea-pigs. The incidence of significant response was below the EEC limit value (30%) to classify the test material as a dermal sensitizer.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Non human data

Skin sensitisation

There is no specific study on isooctene but read-across to the C8 branched olefin, 2,4,4 -trimethylpentene is considered valid. This substance was not a dermal sensitiser when tested in a OECD TG 406 guinea pig maximisation test (HLS, 1997; supporting study). A test group of 20 guinea pigs received 50% 2,4,4-trimethylpentene (in paraffin oil) and Freund’s complete adjuvant for intradermal induction, followed by topical application of undiluted 2,4,4-trimethylpentene under occlusive dressing for 48 hours. In the challenge, 0.03 ml of a 75% and 30% solution of 2,4,4-trimethylpentene (in paraffin oil) was applied to the intact skin for 24 hours under an occlusive dressing. The challenge application of 75% solution resulted in a positive response in 9 treated animals (45%) and 3 control animals (15%); the challenge application of 30% solution resulted in positive response in 3 treated animals (15%) and 1 control animal (5%). Although some response was seen, it was concluded 2,4,4-trimethyl pentene had, at most, a low potential to cause delayed contact hypersensitivity in guinea-pigs and the incidence of significant response was below the EEC limit value (30%) to classify the test material as a dermal sensitiser.

Human data

No data available

Migrated from Short description of key information:
Based on read across to the C8 branched olefin (2,4,4 -trimethylpentene), the evidence indicates that that isooctene is not a skin sensitiser.

Respiratory sensitisation

Endpoint conclusion

Additional information:

No data have been sourced concerning respiratory sensitisation and there are no indications that isooctene is a respiratory allergen.

Migrated from Short description of key information:
There are no specific data on respiratory sensitisation.

Justification for classification or non-classification

There are sufficient data (by read-across) to indicate that isoctene is not a skin sensitiser and no classification is warranted for this end-point under DSD or CLP.

Although there are no specific data on respiratory sensitisation, there is no evidence that classification is warranted for this end-point under DSD or CLP.