2,6-Octadienal, 3,7-dimethyl-, acid-isomerized

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

2,6-Octadienal, 3,7-dimethyl-, acid-isomerized

EC Number:

291-768-8

EC Name:

2,6-Octadienal, 3,7-dimethyl-, acid-isomerized

Cas Number:

90480-35-6

IUPAC Name:

1-methyl-4-(propan-2-yl)benzene; ethanol

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: young adults
- Housing: maximum 4 mice / cage; suspended cages (18.4cm x 52.3cm x 12.7cm)
- Diet: free access to Porton Combined Diet
- Water: ad libitum
- Acclimation period: minimum 4 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 2
- Humidity (%): 55 +/- 15
- Air changes (per hr): 20-30
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (LLNA)

Vehicle:

other: acetone

Concentration:

1, 10 and 30%

No. of animals per dose:

4

Details on study design:

Pre-screen test: A range finding test was not conducted.

Main study
- approx. 25 µl of test preparation applied to the dorsum of each ear
- vehicle control group was similarly treated using acetone
- the procedure was repeated daily for 3 consecutive days
- three days after the third application, all the animals were injected 250 µl of phosphate buffered saline (PBS) containing approx. 20 µCi of a 2.0 Ci/mmol specific activity 3H-methylthymidine 3H(Tdr)
- approx. 5 hours later, the animals were humanely killed by inhalation of halothane vapour followed by cervical dislocation.Sacrifice
- Negative control: vehicle control
- Method: pooled treatment group approach

Evaluation criteria
- Criteria used to consider a positive response: 2 criteria:
a. The increase in isotope incorporation for at least one concentration tested must be 3-fold or more compared with the vehicle control.
b. The data generated must be compatible with a biological dose-response.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:

Hexylcinnamaldehyde has fulfilled the criteria for a potential sensitiser.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

0.8

Test group / Remarks:

1%

Results 2

Parameter:

SI

Value:

2.78

Test group / Remarks:

10%

Results 3

Key result

Parameter:

SI

Value:

4.95

Test group / Remarks:

30%

Applicant's summary and conclusion

Interpretation of results:

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

Conclusions:

The substance is considered to have the capacity to cause contact skin sensitisation.

Executive summary:

In the current study the skin sensitisation potential of the test item was assessed using the Local Lymph Node Assay (LLNA) according to the OECD TG and GLP.

The assay determines the level of T-lymphocyte proliferation in the lymph node draining the site of chemical application, by measuring the amount of radiolabelled thymidine incorporated into the dividing cells.

The concentrations tested were 1, 10 or 30% in acetone and 4 male mice were used per group. The pooled treatment group approach was applied.

Hexylcinnamaldehyde was taken along as a positive control in the study and showed the capacity to cause contact sensitisation when applied as 3 or 10%.

The increase in isotope incorporation was greater than 3-fold at a concentration of 30% (SI = 4.95). Also, the response was consistent with a biological dose-response.

Under the conditions of the test, the test item fulfilled the criteria for a potential sensitiser and therefore the test substance is considered to have the capacity to cause contact skin sensitisation.