tert-pentylbenzene

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 01 June to 11 September 2017.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

tert-pentylbenzene

EC Number:

218-076-0

EC Name:

tert-pentylbenzene

Cas Number:

2049-95-8

Molecular formula:

C11H16

IUPAC Name:

(2-methylbutan-2-yl)benzene

Details on test material:

- Analytical purity: 97.4%
- Impurities: Cumene: 0.7%, Heptylbenzene (C13H18): 0.6%, Nonylbenzene (C15H22): 0.6%
- Lot/batch No.: Tank BV1112 du 18 avril 2007.

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River France, L'Arbresle Cedex, France.
- Age at study initiation: Approx. 10 weeks.
- Weight at study initiation: 20 - 26 g
- Housing: Individual houding in labeled Macrolon cages containing sterilized sawdust as bedding material.
- Diet (e.g. ad libitum): Free access to pelleted rodent food.
- Water (e.g. ad libitum): Free access to tap water.
- Acclimation period: At least 5 days before the start of the treatment under the laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 +/- 3°C.
- Humidity (%): 30-70%
- Air changes (per hr): 15 air changes per hour.
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours darkness.

IN-LIFE DATES: From: 20 June 2007 To: 09 July 2007.

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

0% (vehicle), 25%, 50%, 100%.

No. of animals per dose:

Five animals per dose.

Details on study design:

- RANGE FINDING TESTS: In the preliminary test, two animals were tested and each animal was treated with a test substance concentration of 50% or 100% on three consecutive days. No irritation was observed in any of the animals examined.
MAIN STUDY
- ANIMAL ASSIGNMENT AND TREATMENT: Indicate name of test method used. Comment on criteria used to consider a positive response.
- TREATMENT PREPARATION AND ADMINISTRATION: The dorsal surface of both ears was epidermally treated with 25 μl of the test substance concentration. The application was repeated on days 2 and 3). On day 6 an injection of 250 μl phosphate buffered saline (PBS) containing 20 μCi of 3H-methyl thymidine (3H-TdR) was made into the tail vein of each experimental mouse. Five hours later, the draining Auricular lymph node of each ear was excised into PBS. A single cell suspension of lymph node cells was prepared from each mouse in PBS by gentle separation through stainless steel gauze. LNC were washed twice with an excess of PBS by centrifugation at 200g for 10 minutes at 4°C. Cells were precipitated with 5% trichloroacetic acid at 4 °C for 18 hours.

Positive control substance(s):

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

Statistics:

A Stimulation Index (SI) is calculated for each group. The SI is the ratio of the DPM/group compared to DPM/vehicle control group. The EC3 value (the estimated test substance concentration that will give a SI = 3) was determined using linear interpolation.

Results and discussion

Positive control results:

The six monthly reliability check with Hexylcinnamaldehyde, indicates that the LLNA as performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.4

Test group / Remarks:

25 %

Remarks on result:

other: see Remark

Remarks:

The SI values calculated for the Tertiary-amylbenzene concentrations of 25, 50 and 100% were 1.4, 4.0 and 4.9, respectively. These resutls indicate that the test substance could elicit and SI > 3. The data showed a dose-response and and EC3 value of 40% was calculated. All nodes of the experimental and control groups were considered normal in size.

Results 2

Key result

Parameter:

SI

Value:

4

Test group / Remarks:

50%

Remarks on result:

other:

Remarks:

The SI values calculated for the Tertiary-amylbenzene concentrations of 25, 50 and 100% were 1.4, 4.0 and 4.9, respectively. These resutls indicate that the test substance could elicit and SI > 3. The data showed a dose-response and and EC3 value of 40% was calculated. All nodes of the experimental and control groups were considered normal in size.

Results 3

Key result

Parameter:

SI

Value:

4.9

Test group / Remarks:

100%

Remarks on result:

other:

Remarks:

The SI values calculated for the Tertiary-amylbenzene concentrations of 25, 50 and 100% were 1.4, 4.0 and 4.9, respectively. These resutls indicate that the test substance could elicit and SI > 3. The data showed a dose-response and and EC3 value of 40% was calculated. All nodes of the experimental and control groups were considered normal in size.

Results 4

Key result

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Mean DPM/Aminal values for the experimental groups treated with Tertiary-amylbenzene concentrations 25, 50 and 100% were 441, 1284 and 1561, respectively. The mean DPM/aminal value for the vehicle control group was 3190

Results 5

Key result

Parameter:

EC3

Value:

ca. 40

Applicant's summary and conclusion

Interpretation of results:

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

Conclusions:

Under the test conditions of this study, the test item Tertiary-amylbenzene induced delayed contact hypersensitivity in the murine Local Lymph Node Assay (EC3 value of 40%). Therefore, Tertiary-amylbenzene is classified into Category 1B, H317 according to EU criteria.

Executive summary:

In a dermal sensitization study (Notox, 2007) with Tertiary-amylbenzene in acetone/olive oil (4/1), young adults CBA female mice (5 per group), were tested using the method of LLNA (OECD 429, GLP).

The test item was soluble in the first recommended vehicle, acetone/olive oil (4/1, v/v). A solution was obtained at the maximum tested concentration of 100%. Consequently, the concentrations selected for the main study were 0, 25, 50 and 100%.

No skin reactions were observed in any of the animals examined. All nodes of the experimental and control groups were considered normal in size.

Mean DPM/animal values for the experimental groups treated with test substance concentrations 25, 50 and 100% were 441, 1284 and 1561 respectively. The mean DPM/animal value for the vehicle control group was 319.

The SI values calculated for the substance concentrations 25, 50 and 100% were 1.4, 4.0 and 4.9 respectively. These results indicate that the test substance could elicit an SI >= 3. The data showed a dose response and an EC3 value of 40% was calculated.

Under the experimental conditions of this study, the test item Tertiary-amylbenzene induced delayed contact hypersensitivity in the murine Local Lymph Node Assay. According to the results obtained in this study, the test item should be classified as sensitizing to the skin, into category 1B, H317 according to EU criteria.