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

Endpoint summary

Description of key information

The study was conducted to recognised testing guidelines, and with GLP certification.

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:

2013

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:

adopted July 2010

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)

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

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)

Parameter:

SI

Value:

1.5

Test group / Remarks:

10%

Parameter:

SI

Value:

5

Test group / Remarks:

25%

Parameter:

SI

Value:

6.7

Test group / Remarks:

50%

Parameter:

EC3

Value:

16.4

Test group / Remarks:

%

Parameter:

other: DPM

Value:

424.5

Test group / Remarks:

Control

Parameter:

other: DPM

Value:

634.9

Test group / Remarks:

10%

Parameter:

other: DPM

Value:

2 123.1

Test group / Remarks:

25%

Parameter:

other: DPM

Value:

2 837.7

Test group / Remarks:

50%

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.

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.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Three groups of five female mice each were treated once daily with ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate at concentrations of 10, 25, and 50% in acetone:olive oil (4+1, v/v) by topical application to the dorsum of each ear for three consecutive days (BASF 2013). Five days after the first topical application the mice were injected intravenously into the tail vein with radio-labelled thymidine (3H-methyl thymidine) and sacrificed 5 hours later. The animals did not show any signs of systemic toxicity during the course of the study and no mortality occured. A statistically significant increase in ear weights was observed in all dose groups in comparison to the vehicle control group (p<0.05). Furthermore, for BALB/c mice, a cutoff-value of 1.1 for the ear weight index was reported for a positive response regarding ear skin irritation. The indices determined (1.08, 1.13, and 1.16, respectively) for all test item treated groups reached or exceeded this threshold, but not the cutoff value of 1.25 for excessive skin irritation cited in the OECD guideline. A statistically significant and biologically relevant increase in DPM value and also 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. Stimulation Indices (S.I.) of 1.5, 5.0, and 6.7 were determined with the test item at concentrations of 10, 25, and 50% in acetone:olive oil (4+1, v/v), respectively. A dose response was observed and an EC3 value of 16.4 % was derived. 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 (index of 2.0 and 2.2).

Migrated from Short description of key information:
LLNA: sensitizing, EC3=16.4% (BASF 2013, GLP, OECD 429)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

In the LLNA ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate was demonstrated to be a skin sensitizer due to a dose dependent increase in lymphocyte proliferation and an S.I. value >3 at the two highest concentration tested. The EC 3 value was calculated to be 16.4%, which is above the threshold of 2% for classification as Cat. 1A according to GHS-criteria. Thus, the effects justify classification as a sensitizer cat. 1B according to CLP/GHS-EU and with R43 according to 67/548/EEC.

There are no data available for classification of ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate as a sensitizer of the respiratory tract.