Phosphorous acid, mixed 2,4-bis(1,1-dimethylpropyl)phenyl and 4-(1,1-dimethylpropyl)phenyl triesters

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8th December 2009 to 24th December 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of GLP inspection: 15/09/09 Date of Signature on GLP certificate: 26/11/09

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of bis[2,4-bis(2-methylbutan-2-yl)phenyl] 4-(2-methylbutan-2-yl)phenyl phosphite and 2,4-bis(2-methylbutan-2-yl)phenyl bis[4-(2-methylbutan-2-yl)phenyl] phosphite and tris[4-(2-methylbutan-2-yl)phenyl] phosphite.

EC Number:

700-485-5

Cas Number:

939402-02-5

Molecular formula:

Mixture of 4 components, the molecular formulae of which are: C33 H45 O3 P, C38 H55 O3 P, C43 H65 O3 P and C48 H75 O3 P

IUPAC Name:

Reaction mass of bis[2,4-bis(2-methylbutan-2-yl)phenyl] 4-(2-methylbutan-2-yl)phenyl phosphite and 2,4-bis(2-methylbutan-2-yl)phenyl bis[4-(2-methylbutan-2-yl)phenyl] phosphite and tris[4-(2-methylbutan-2-yl)phenyl] phosphite.

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories UK Limited, Bicester, Oxon, UK.
- Age at study initiation: eight to twelve weeks old.
- Weight at study initiation: 15 to 23 g
- Housing: individually housed in suspended solid floor polypropylene cages furnished with softwood woodflakes.
- Diet: ad libitum - (2014 Teklad Global Rodent diet supplied by Harlan Teklad, Blackthorn, Bicester, Oxon, UK)
- Water: ad libitum - mains tap water
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25°C
- Humidity (%): 30 to 70%
- Air changes (per hr): approximately fifteen changes per hour
- Photoperiod (hrs dark / hrs light): lighting was controlled by a time switch to give twelve hours continuous light (06.00 to 18.00) and twelve hours darkness

IN-LIFE DATES: From: Day of dosing (Day 1) To: Day of termination (day 6)

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

Preliminary screening test: 50% v/v in acetone/olive oil 4:1

Main test: 50%, 25% and 10% v/v in acetone/olive oil 4:1

No. of animals per dose:

Preliminary screening test: 1 mouse

Main test: Five mice per dose level

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: For the purpose of the study, the test material was freshly prepared as a solution in acetone/olive oil 4:1.
- Irritation: The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Any signs of toxicity or excessive local irritation noted during this period were recorded.
- Lymph node proliferation response: not performed for preliminary screening test

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response: The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph nodes from each individual animal and as the ratio of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index).

The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non sensitiser".

TREATMENT PREPARATION AND ADMINISTRATION: Groups of five mice were treated with the test material at concentrations of 50%, 25% or 10% v/v in acetone/olive oil 4:1. The preliminary screening test suggested that the test material would not produce systemic toxicity or excessive local irritation at the highest suitable concentration. The mice were treated by daily application of 25 µl of the appropriate concentration of the test material to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test material formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette. A further group of five mice received the vehicle alone in the same manner.

Positive control substance(s):

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

Statistics:

Data was processed to give group mean values for disintegrations per minute and standard deviations where appropriate. Individual and group mean disintegrations per minute values were assessed for dose response relationships by analysis of homogeneity of variance followed by one way analysis of variance (ANOVA). In the event of a significant result from the ANOVA, pairwise comparisons were performed between control and treated groups. For homogenous datasets Dunnett’s Multiple Comparison test was used and for non homogenous datasets Dunnett’s T3 Multiple Comparison Method was used.
Probability values (p) are presented as follows:
P<0.001 ***
P<0.01 **
P<0.05 *
P>0.05 (not significant)

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1.04

Test group / Remarks:

50%

Results 2

Parameter:

SI

Value:

0.79

Test group / Remarks:

25%

Results 3

Parameter:

SI

Value:

1.57

Test group / Remarks:

10%

Results 4

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Vehicle: Mean DPM of 2109.44 10%: Mean DPM of 3309.32 25%: Mean DPM of 1659.66 50%: Mean DPM of 2201.86

Any other information on results incl. tables

Interpretation of results

The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph nodes from each individual animal and as the ratio of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index). The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non sensitiser".

Estimation of the proliferative response of lymph node cells

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%v/v) in acetone/olive oil 4:1	Stimulation Index	Result
10	1.57	Negative
25	0.79	Negative
50	1.04	Negative

Clinical Observations and Mortality Data

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.

Bodyweight

Bodyweight changes of the test animals between Day 1 and Day 6 were comparable to those observed in the corresponding control group animals over the same period.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The test material was considered to be a non-sensitiser under the conditions of the test.

Executive summary:

Introduction. A study was performed to assess the skin sensitisation potential of the test material in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The method was designed to meet the requirements of the following:

-  OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay" (adopted 24 April 2002)

-  Method B42 Skin Sensitisation (Local Lymph Node Assay) of CommissionRegulation (EC) No. 440/2008

Methods. Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 50% v/v, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of five animals, were treated with 50 µl (25 µl per ear) of the test material as asolutioninacetone/olive oil 4:1at concentrations of 50%, 25% or 10% v/v. A further group of five animals was treated with acetone/olive oil 4:1alone.

Results. The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%v/v) in acetone/olive oil 4:1	Stimulation Index	Result
10	1.57	Negative
25	0.79	Negative
50	1.04	Negative

Conclusion. The test material was considered to be a non-sensitiser under the conditions of the test.