Ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted July 2010

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

adopted May, 2008

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate

EC Number:

282-810-6

EC Name:

Ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate

Cas Number:

84434-11-7

Molecular formula:

C18H21O3P

IUPAC Name:

ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate

Details on test material:

- Name of test material (as cited in study report): Lucirin TPO-L
- Physical state: Liquid, viscous /yellow, clear
- Analytical purity: 95.7g/100g determined by H-NMR spectroscopy
- Purity test date: 2013-04-16
- Lot/batch No.: Mischung 120204
- Expiration date of the lot/batch: May 29th, 2015
- Storage condition of test material: Room temperature; under light exclusion

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories B.V., Netherlands
- Age at study initiation: 8-9 weeks
- Weight at study initiation: 19 - 22g
- Housing: groups of 5 in Makrolon type III cages
- Diet (e.g. ad libitum): 2018C Teklad Global 18% protein rodent diet (certified), ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): temperature 22 +/- 2°C
- Humidity (%): 45-65%, the relative humidity in the animal room was between approximately 24 - 45 % instead of 45 – 65% for few hours. This deviation to the study plan, however, does not affect the validity of the study.
- Photoperiod (hrs dark / hrs light): 12h/12h

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

10%, 25%, 50%

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- The highest concentration which could technically be used was 50%
- Irritation: At the tested concentrations the animals did not show any signs of systemic toxicity. From day 3 to day 5, both animals showed an erythema of the ear skin (day 3 and day 4: Score 2, day 5: Score 1 for both animals). Neither ear weights nor measurement of ear swelling indicated ear irritation.

MAIN STUDY
- Criteria used to consider a positive response:
1) exposure to at least one concentration of the test item resulted in an incorporation of 3HTdR at least 3-fold or greater than that recorded in control mice, as indicated by the Stimulation Index.
2) data are compatible with a conventional dose response, although allowance must be made (especially at high topical concentrations) for either local toxicity or immunological suppression.

TREATMENT PREPARATION AND ADMINISTRATION:
The different test item concentrations were prepared individually before each dosing occasion.
Each test group of mice was treated by (epidermal) topical application to the dorsal surface of each ear. The application volume, 25 μL/ear/day, was spread over the entire dorsal surface (∅ ∼ 8 mm) of each ear once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone. Five days after the first topical application 250 μL of phosphate-buffered saline containing 20.3 μCi of 3H-methyl thymidine (equivalent to 81.1 μCi/mL 3HTdR) were injected into each test and control mouse via the tail vein. 5 hours later, the animals were killed and the draining lymph nodes excised and pooled per animal.

Positive control substance(s):

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

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1.5

Test group / Remarks:

10%

Results 2

Parameter:

SI

Value:

5

Test group / Remarks:

25%

Results 3

Parameter:

SI

Value:

6.7

Test group / Remarks:

50%

Results 4

Parameter:

EC3

Value:

16.4

Test group / Remarks:

%

Results 5

Parameter:

other: DPM

Value:

424.5

Test group / Remarks:

Control

Results 6

Parameter:

other: DPM

Value:

634.9

Test group / Remarks:

10%

Results 7

Parameter:

other: DPM

Value:

2 123.1

Test group / Remarks:

25%

Results 8

Parameter:

other: DPM

Value:

2 837.7

Test group / Remarks:

50%

Any other information on results incl. tables

No signs of systemic toxicity were observed during the study period. From day 3 to day 5, the animals treated with a test item concentration of 50% showed an erythema of the ear skin (Score 1). Animals treated with 10 and 25% test item concentration did not show any local signs.

A statistically significant and biologically relevant increase in lymph node weight and cell count was observed in the mid and high dose group in comparison to the vehicle control group corroborating the presence of a positive response. Furthermore, the cutoff-value of 1.55 for a positive response regarding the lymph node cell count index reported for BALB/c mice was exceeded in the mid and high dose group (indices of 2.0 and 2.2).

A statistically significant increase in ear weights was observed in all dose groups in comparison to the vehicle control group (p<0.05). The indices determined (1.08, 1.13, and 1.16, repectively) for all test item treated groups (10%, 25%, 50%) did not exceed the cutoff value of 1.25 for excessive skin irritation cited in the OECD guideline.

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

The test material was found to induce a sensitising reaction in the mouse.