1,4-phenylene bis((4-hydroxyphenyl)methanone)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 January 2018 - 04 April 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The results obtained from the available in silico/in chemico/in vitro studies are not adequate for classification and risk assessment.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

July 2010

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EC No 640/2012, Part B: Skin sensitization: "Local Lymph Node Assay"

Version / remarks:

July 2012

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

March 2003

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:

4-[4-(4-hydroxybenzoyl)benzoyl]phenol

EC Number:

816-326-9

Cas Number:

15517-46-1

Molecular formula:

C20H14O4

IUPAC Name:

4-[4-(4-hydroxybenzoyl)benzoyl]phenol

Test material form:

solid: crystalline

Details on test material:

- Identification: 1,4-Bis (4-hydroxy benzoyl) benzene
- Appearance: Off white crystalline powder
- Test item storage: At room temperature
- Stable under storage conditions until: 15 May 2018 (expiry date)

Specific details on test material used for the study:

- Appearance: Off white crystalline powder
- Test item storage: At room temperature
- Stable under storage conditions until: 15 May 2018 (expiry date)

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/J

Sex:

female

Details on test animals and environmental conditions:

- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: Young adult animals (approx. 10 weeks old)
- Weight at study initiation: 17.2 - 23.2 g
- Housing: Animals were group housed (up to 5 animals together) in labeled Makrolon cages containing sterilized sawdust as bedding material.
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany).
- Water: Free access to tap water.
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS (daily mean)
- Temperature (°C): 22 - 23
- Humidity (%): 41 - 43
- Air changes (per hr): 10 or greater
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 10 January 2018 - 5 February 2018

Study design: in vivo (LLNA)

Vehicle:

methyl ethyl ketone

Concentration:

0, 10, 25, 50% (w/w) (main study)
25, 50% (w/w) (pre-test)

No. of animals per dose:

5 (main study)
2 (pre-test)

Details on study design:

RANGE FINDING TESTS:
Two test item concentrations were tested: a 25% and 50% concentration. The highest concentration was the maximum concentration as required in the test guidelines.
The test system, procedures and techniques were identical to those used in the main study except that the assessment of lymph node proliferation and necropsy were not performed. Two young adult animals per concentration were selected. Each animal was treated with one concentration on three consecutive days. Animals were group housed in labeled Makrolon cages (MII type, height 14 cm). Ear thickness measurements were conducted using a digital thickness gauge (prior to dosing on days 1 and 3, and on day 6.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response: DPM values are presented for each animal and for each dose group. A Stimulation Index (SI) is calculated for each group using the individual SI values. The individual SI is the ratio of the DPM/animal compared to DPM/vehicle control group mean. If the results indicate a SI ≥ 3, the test substance may be regarded as a skin sensitizer, based on the test guideline and recommendations done by ICCVAM.

ANIMAL ASSIGNMENT
Three groups of five animals were treated with one test substance concentration per group. One group of five animals was treated with vehicle.

TREATMENT PREPARATION AND ADMINISTRATION:
Test substance preparation: Test item dosing formulations (w/w) were homogenized to visually acceptable levels at appropriate concentrations to meet dose level requirements. The dosing formulations were prepared daily and dosed within 4 hours after adding the vehicle to the test item and were kept at room temperature until dosing. The dosing formulations were stirred until and during dosing. No adjustment was made for specific gravity of the vehicle and no correction was made for the purity/composition of the test item, since the test method requires a logical concentration range rather than specific dose levels.

Rationale for vehicle: The vehicle was chosen from the vehicles specified in the test guideline. The vehicle was selected on the basis of maximizing the solubility based on trial preparations performed at Charles River Den Bosch and on information provided by the Sponsor.

Induction - Days 1, 2 and 3; Excision of nodes - Day 6; Tissue processing for radioacitivity - Day 6; Radioactivity measurements - Day 7; Performed according to test guidelines.

OBSERVATIONS:
Mortality/Viability: Twice daily.
Body weights: On day 1 (pre-dose) and day 6 (prior to necropsy).
Clinical signs: Once daily on days 1-6 (on days 1-3 between 3 and 4 hours after dosing).
Irritation: Once daily on days 1-6 (on days 1 - 3 within 1 hour after dosing) according to a numerical scoring system (according to guideline). Furthermore, a description of all other (local) effects was recorded according to guidelines.
Necropsy: No necropsy was performed, since all animals survived until the end of the observation period.

Positive control substance(s):

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

Statistics:

Not performed.

Results and discussion

Positive control results:

The six-month reliability check with Alpha-hexylcinnamaldehyde indicates that the Local Lymph Node Assay as performed at Charles River Den Bosch is an appropriate model for testing for contact hypersensitivity.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.8

Variability:

0.4 (standard error of the mean)

Test group / Remarks:

10%

Remarks on result:

other: Since there was no indication that the test item elicits a SI ≥ 3 when tested up to 50%, the substance was not considered to be a skin sensitizer

Results 2

Key result

Parameter:

SI

Value:

0.7

Variability:

0.1 (standard error of the mean)

Test group / Remarks:

25%

Remarks on result:

other: Since there was no indication that the test item elicits a SI ≥ 3 when tested up to 50%, the substance was not considered to be a skin sensitizer

Results 3

Key result

Parameter:

SI

Value:

1.1

Variability:

0.2 (standard error of the mean)

Test group / Remarks:

50%

Remarks on result:

other: Since there was no indication that the test item elicits a SI ≥ 3 when tested up to 50%, the substance was not considered to be a skin sensitizer

Cellular proliferation data / Observations:

Mean DPM/animal values for the experimental groups treated with test item concentrations 10, 25 and 50% were 700, 281 and 432 DPM, respectively. The mean DPM/animal value for the vehicle control group was 387 DPM. The SI values calculated for the test item concentrations 10, 25 and 50% were 1.8, 0.7 and 1.1, respectively.

Any other information on results incl. tables

Results Pre-screen test:

At a 25% and 50% test item concentration, no signs of systemic toxicity were noted and no irritation was observed and therefore the 50% concentration was selected as highest concentration for the main study.

Other results - main study:

Skin Reactions / Irritation

No erythema was observed in any of the animals. The scaliness as noted for four control animals on days 2 and/or 3 was considered not to have a toxicologically significant effect on the activity of the nodes. Brown test item remnants were present on the dorsal surface of the ears of all test item treated animals throughout the observation period, which did not hamper scoring of the skin reactions.

Macroscopic  Examination of the Lymph Nodes and Surrounding Area

All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals.

Systemic Toxicity and bodyweight

No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In an LLNA skin sensitisation study, performed according to OECD/EC test guidelines and in accordance with GLP principles, 1,4-Bis (4-hydroxy benzoyl) benzene was considered not to be a skin sensitiser, as the SI appeared not to be ≥ 3 when tested up to 50% (w/w).

Executive summary:

An LLNA skin sensitisation study was performed according to OECD/EC test guidelines and GLP principles. Based on the results of a pre-screen test, the test concentrations were selected at 10%, 25% and 50% w/w. No erythema was observed in any of the animals. All auricular lymph nodes were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals. No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. Mean DPM/animal values for the experimental groups treated with test item concentrations 10, 25 and 50% were 700, 281 and 432 DPM, respectively. The mean DPM/animal value for the vehicle control group was 387 DPM. The SI values calculated for the test item concentrations 10, 25 and 50% were 1.8, 0.7 and 1.1, respectively. As the SI appeared not to be ≥ 3 when tested up to 50% w/w, 1,4-Bis (4-hydroxy benzoyl) benzene was not considered to be a skin sensitiser.