3-(4-tert-butylphenyl)propionaldehyde

Endpoint summary

Description of key information

In an OECD guideline study performed according to GLP, the test item has the capacity to cause skin sensitisation when applied as dose levels of 5, 10 and 25 % w/v preparations in 1:3 EtOH:DEP. The EC3 value giving rise to a three-fold increase in lymphocyte proliferation was calculated to be 4.3 % w/v (1075 µg/cm2).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 16, 2006 to June 27, 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan UK Limited, Shaw's Farm, Blackthorne, Bicester, Oxon, UK
- Age at study initiation: Young adults(8-12 weeks old)
- Weight at study initiation: Ranged from 16.6 to 20.6 g
- Housing: maximum of 4 mice housed per cage, in cages suitable for animal sof thi sstrain and weight range. Environemntal enrichment provided included tents, bases and nestlets.
- Diet (e.g. ad libitum): RM1, supplied by Special Diet Services Limited, Within, Essex, UK.
- Water (e.g. ad libitum): From mains supply
- Acclimation period: At least 5 day sprior to start of dosing.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3°C
- Humidity (%): 30-70%
- Air changes (per hr): Minimum of 15 changes per hour
- Photoperiod (hrs dark / hrs light): Artificial light, giving 12 hours light, 12 hours dark.

IN-LIFE DATES: From: June 21, 2006 To: June 27, 2006

Vehicle:

other: 1:3 Ethanol/ Diethylphthalate

Concentration:

1, 2.5, 5, 10 and 25 % w/v

No. of animals per dose:

4

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: Not reported
- Irritation: Not reported
- Lymph node proliferation response:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method:
- Criteria used to consider a positive response:

TREATMENT PREPARATION AND ADMINISTRATION:
RANGE FINDING TESTS:
- Compound solubility:
- Irritation:
- Lymph node proliferation response:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method:
- Criteria used to consider a positive response: The results are expressed as a disintegration per minute (dpm) value per each group. The activity of each test group is then divided by the activity of the vehicle control group to give a test: control ratio known as the stimulation index (SI) for each concentration. The criteria for a positive response is that one or more concentrations of the test substance should elicit a 3-fold or greater increase in isotope incorporation relative to the vehicle control group. The assay is able to identify those materials that elicit responses in a standard Magnusson and Kligman maximisation guinea pig test for sensitisation. Consequently, a test substance which does not fulfi the crierion is designated as unlikely to be a skin sensitiser.

TREATMENT PREPARATION AND ADMINISTRATION: Groups of four female mice were used for this study. Approximately 25µL of a 1,2.5, 5, 10 or 25% w/v preparation of the test substance in 1:3 EtOH: DEP was applied, using a variable volume micro-pipette, to the dorsal surface of each ear. A vehicle control group was similarly treated using 1:3 EtOH:DEP alone. The procedure was repeated daily for 3 consecutive days.
Three days after final application, all the animals were injected, via the tail vein, with approximately 250µL of phosphate buffered saline (PBS) containing 20µCi of a 2.0Ci/mmol Specific activity 3H-methyl thymidine. Approximatley 5 hours later, the animals were humanely killed by inhalation of halothane followed by cervical dislocation. The draining auricular lymph nodes were removed from each animal, and together with the nodes from the other animals in the group, were placed in a container with PBS.
A single cell suspension was prepared by mechanical disaggregation of lymph nodes through 200-mesh stainless steel gauze. The cell suspensions were then washed three times by centrifugation with approximately 10mL of PBS. Approximately 3mL of 5% w/v trichloroacetic acid (TCA) was added and after, overnight precipitation at 4°C, the samples were pelleted by centrifugation and the supernatant was discarded. The cells were then resuspended in approximately 1mL of TCA.

The lymph node suspensions were transferred to scintillation vials and 10mL of scintillant (Optiphase) was added prior to ß-scintillation counting using a Packard Tri-Carb 3100TR Liquid Scintillation Counter

Positive control substance(s):

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

Positive control results:

In a positive control study, hexylcinnamaldehyde was shown to have the capacity to cause skin sensitisation when applied as a 25% (w/v) preparation in acetone: olive oil (4:1), confirming the validity of the protocol used for this study.
The reliability of the protocol using a positive control was conducted between January 25, 2006 and January 31, 2006.

Parameter:

SI

Value:

0.9

Test group / Remarks:

concentration 1% w/v

Parameter:

SI

Value:

1.4

Test group / Remarks:

concentration 2.5% w/v

Parameter:

SI

Value:

3.6

Test group / Remarks:

concentration 5% w/v

Parameter:

SI

Value:

4.2

Test group / Remarks:

concentration 10% w/v

Parameter:

SI

Value:

9.8

Test group / Remarks:

concentration 25% w/v

Key result

Parameter:

EC3

Value:

4.3

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Remarks:

Migrated information

Conclusions:

The test item has the capacity to cause skin sensitisation when applied as dose levels of 5, 10 and 25% w/v preparations in 1:3 EtOH:DEP. The EC3 value giving rise to a three-fold increase in lymphocyte proliferation was calculated to be 4.3% w/v (1075µg/cm2).

Executive summary:

The test item, Bourgeonal, was tested for potential skin sensitisation according to OECD guideline 429.

The application of the test substance at concentrations of 1, 2.5, 5, 10 and 25 % w/v in 1:3 EtOH:DEP resulted in an isotope incorporation, which was greater than 3 -fold at the 5, 10 and 25 % w/v concentrations. Consequently, the test substance is likely to be a skin sensitiser under the conditionsof the test. The concentration giving rise to a 3 -fold increase in lymphocyte proliferation (EC3) was calculated to be 4.3% w.v (1075 µg/cm2).

The application of a positive control, hexylcinnamaldehyde, at concentrations of 5%, 10% and 25% w/v in acetone:olive oil (4:1) resulted in greater than 3 -fold increase in isotope incorporation at the 25% w/v concentration. Therefore, hexylcinnamaldehyde was shown to be a skin sensitiser, confirming the validity of the protocol used for the study.

In conclusion, Bourgeonal in 1:3 EtOH:DEP vehicle is a skin sensitiser under the conditions of the test with an EC3 value of 4.3% (1075 µg/m2).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The test substance was assessed for skin sensitisation according to OECD Guideline 429. The test item has the capacity to cause skin sensitisation when applied as dose levels of 5, 10 and 25 % w/v preparations in 1:3 EtOH:DEP. The EC3 value giving rise to a three-fold increase in lymphocyte proliferation was calculated to be 4.3 % w/v (1075 µg/cm2).

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The test material was found to be sensitising in a local lymph node assay.