2,4,8,10-tetra(tert-butyl)-6-hydoroxy-12H-dibenzo[d,g] [1,3,2]dioxaphosphocin, 6-oxide

Endpoint summary

Description of key information

Skin sensitisation:

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

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:

From 2018-01-02 to 2018-01-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Specific details on test material used for the study:

Purity: > 99%
Batch No.: 102Z4

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: Young adult animals (approximately 10 weeks old)
- Weight at study initiation: 18.3 to 24.1 g
- Housing: in polycarbonate cages (Makrolon MIII type; height 18 cm.)
- Diet (e.g. ad libitum): ad libitum throughout the study, except during designated procedures.
- Water (e.g. ad libitum): freely available via water bottles
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 to 23 °C
- Humidity (%): 42 to 60%
- Air changes (per hr): Ten or greater
- Photoperiod (hrs dark / hrs light): a 12-hour light/12-hour dark cycle

Vehicle:

propylene glycol

Concentration:

Pre-screen test: 25 and 50% test item concentration
Main study: test item concentrations of 10, 25 or 50% w/w

No. of animals per dose:

Pre-screen test: two young adult animals per concentration
Main study: five animals per concentration

Details on study design:

PRE-SCREEN TESTS:
- Ear thickness measurements: conducted using a digital thickness gauge prior to dosing on Days 1 and 3, and on Day 6
- Results: At a 25 and 50% test item concentration, no signs of systemic toxicity were noted and very slight irritation at the most were observed and therefore a 50% concentration was selected as highest concentration for the main study.

MAIN STUDY

INDUCTION EXPOSURE
- Exposure period: days1, 2, 3
- Test groups: treated (25 μL/ear) with the test item, at approximately the same time
- Control group: treated in the same way as the experimental animals, except that the vehicle was administered instead of the test item
- Site: the dorsal surface of both ears
- Frequency of applications: each day

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Radioactivity measurements
- Criteria used to consider a positive response: If the results indicate a SI ≥ 3, the test item may be regarded as a skin sensitizer.

TREATMENT PREPARATION AND ADMINISTRATION:
- Preparation of test item: 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. The dosing formulations were kept at room temperature until dosing. The dosing formulations were stirred until and during dosing.
- Administration: Three groups of five animals were treated with one test item concentration per group. The highest test item concentration was selected from the pre-screen test. One group of five animals was treated with the vehicle.

Key result

Parameter:

SI

Value:

2.6

Test group / Remarks:

10% test item concentration

Key result

Parameter:

SI

Value:

1.4

Test group / Remarks:

25% test item concentration

Key result

Parameter:

SI

Value:

1.8

Test group / Remarks:

50% test item concentration

Cellular proliferation data / Observations:

- Skin Reactions / Irritation:
No irritation was observed in any of the animals. White test item remnants were present on the dorsal surface of the ears of all animals treated at 50% between Days 1 and 3 which did not hamper scoring of the skin reactions.
- Systemic Toxicity:
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.
- 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 surroundin area were noted for any of the animals.

Radioactivity Measurements:

Mean DPM/animal values for the experimental groups treated with test item concentrations 10, 25 and 50% were 1257, 660 and 858 DPM, respectively. The mean DPM/animal value for the vehicle control group was 478 DPM.

Interpretation of results:

other: unclassified

Conclusions:

The test substance was considered not to be a skin sensitizer.

Executive summary:

The objective of this study was to evaluate whether the test item induces skin sensitization in mice after three epidermal exposures of the animals according to OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay).

Test item concentrations selected for the main study were based on the results of a pre-screen test. At a 25 and 50% test item concentration, no signs of systemic toxicity were noted and very slight irritation at the most were observed and therefore a 50% concentration was selected as highest concentration for the main study.

In the main study, three experimental groups of five female CBA/J mice were treated with test item concentrations of 10, 25 or 50% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with the vehicle alone (Propylene glycol). Three days after the last exposure, all animals were injected with ³H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of disintegrations per minute (DPM) and a stimulation index (SI) was subsequently calculated for each group.

No irritation was observed in 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. 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.

Mean DPM/animal values for the experimental groups treated with test item concentrations 10, 25 and 50% were 1257, 660 and 858 DPM, respectively. The mean DPM/animal value for the vehicle control group was 478 DPM. The SI values calculated for the test item concentrations 10, 25 and 50% were 2.6, 1.4 and 1.8, respectively.

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

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The objective of this study was to evaluate whether the test item induces skin sensitization in mice after three epidermal exposures of the animals according to OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay).

Test item concentrations selected for the main study were based on the results of a pre-screen test. At a 25 and 50% test item concentration, no signs of systemic toxicity were noted and very slight irritation at the most were observed and therefore a 50% concentration was selected as highest concentration for the main study.

In the main study, three experimental groups of five female CBA/J mice were treated with test item concentrations of 10, 25 or 50% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with the vehicle alone (Propylene glycol). Three days after the last exposure, all animals were injected with ³H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of disintegrations per minute (DPM) and a stimulation index (SI) was subsequently calculated for each group.

No irritation was observed in 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. 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.

Mean DPM/animal values for the experimental groups treated with test item concentrations 10, 25 and 50% were 1257, 660 and 858 DPM, respectively. The mean DPM/animal value for the vehicle control group was 478 DPM. The SI values calculated for the test item concentrations 10, 25 and 50% were 2.6, 1.4 and 1.8,respectively.

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

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Skin sensitisation:

Negative result in animal test (LLNA).

Therefore, according to Regulation (EC) 1272/2008 (amendment 286/2011) Table 3.4.2, this substance should not be classified for skin sensitisation endpoint.