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Toxicological information

Skin sensitisation

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Administrative data

skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
29 September 2009 - 19 October 2009
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study has been performed according to EC and/or OECD guidelines and in compliance with GLP principles.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guidelineopen allclose all
according to guideline
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
according to guideline
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
according to guideline
EPA OPPTS 870.2600 (Skin Sensitisation)
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Chemical structure
Reference substance name:
Tris(methylphenyl) phosphite
EC Number:
EC Name:
Tris(methylphenyl) phosphite
Cas Number:
Molecular formula:
tris(methylphenyl) phosphite
Details on test material:
- Name of test material (as cited in study report): TTP
- Substance type: Clear colourless liquid
- Physical state: Liquid
- - Analytical purity:>92,1%
- Impurities: - 7,5% Phosphorochloridous acid, bis-methylphenyl)ester
- 0,4% Cresol
(the initial purity information in the study report (which was 99%) was corrected by a report amendement on 13. Feb 2012)

- Lot/batch No.: HR9C77938
- Expiration date of the lot/batch: 31 March 2010
- Stability under test conditions: Test substance is stable in both acetone and in olive oil and the vehicle for this test is acetone/olive oil (4:1 v/v))
- Storage condition of test material: At room temperature in the dark under nitrogen

In vivo test system

Test animals

Details on test animals and environmental conditions:
- Source: Charles River France, L¿Arbresle Cedex, France.
- Age at study initiation: approx. 10 weeks old
- Weight at study initiation: 21 -25 gram
- Housing: Individual housing in labeled Macrolon cages containing sterilized sawdust as bedding material. Paper was supplied as cage-enrichment. The paper was removed on Day 1 prior to dosing and was supplied again after scoring of the ears on Day 3.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

- Temperature (°C): 21.1 ¿ 24.0ºC
- Humidity (%): 31 - 74%
- Air changes (per hr): approximately 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 29 September 2009 To: 19 October 2009

Study design: in vivo (LLNA)

acetone/olive oil (4:1 v/v)
0% - 2.5% - 5% - 10%
No. of animals per dose:
Details on study design:
- Compound solubility: Homogeneity of formulations were obtained to visually acceptable levels
- Mortality/toxicity: Both animals treated with test susbstance concentrations of 50% and 100% were found dead on Day 3 and body weight loss was observed for the animal treated with test substance concentration 25%. At a 10% test substance concentration no signs of systemic toxicity were noted and no severe irritation was observed.
- Irritation: Well-dfined erythema in the animal treated at 25% test substance concentration and slight erythema in the animal at 10% test substance concentration.

- 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. The SI is the ratio of the DPM/group compared to DPM/vehicle control group. 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 (Reference 1).

The test substance formulations (w/w) were prepared within 4 hours prior to each treatment. No adjustment was made for specific gravity of the vehicle. Homogeneity was obtained to visually acceptable levels.
Three groups of five animals were treated with test substance concentration of 10, 25 or 50% on three consecutive days. The dorsal surface of both ears was epidermally treated (25 µL/ear) with the test substance concentration, at approximately the same time per day. The concentrations were mixed thoroughly using a vortex mixer immediately prior to dosing. The control animals were treated the same as the experimental animals, except that, instead of the test substance, the vehicle alone (Acetone/Olive oil (4:1 v/v)) was administered.
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. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
No statistical analysis was performed.

Results and discussion

Positive control results:
The SI values calculated for the substance concentrations 5, 10 and 25% were 1.4, 1.2 and 5.1 respectively. An EC3 value of 16.9% was calculated using linear interpolation. The calculated EC3 value was found to be in the acceptable range of 2 and 20%. The results of the 6 monthly HCA reliability checks of the recent years were 13.1, 15.6, 14.1, 13.8, 13.9, 16.0 and 11.9%.
Based on the results, it was concluded that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

In vivo (LLNA)

Resultsopen allclose all
Remarks on result:
other: 0% (vehicle): 1.0 ± 0.3 2.5%: 4.8 ± 1.3 5%: 13.3 ± 3.3 10%: 26.2 ± 7.8
other: disintegrations per minute (DPM)
Remarks on result:
other: 0% (vehicle): 431 ± 94 2.5%: 2055 ± 302 5%: 5734 ± 690 10%: 11294 ± 2279

Any other information on results incl. tables

No irritation of the ears was observed in any of the animals examined.

All auricular lymph nodes of control animals were considered normal in size. The majority of auricular lymph nodes of animals treated with test substance formulations were considered enlarged in size, except for the nodes in one animal treated at 2.5%. The largest auricular lymph nodes were found in the higher dose groups. No macroscopic abnormalities of the surrounding area were noted.


Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.

No mortality occurred and no symptoms of systemic toxicity were observed in the animals of the main study.

Applicant's summary and conclusion

Interpretation of results:
Migrated information
These results show that the test substance elicits an SI = 3. The EC3 value (the estimated test substance concentration that will give a SI =3) was established to be between 0 and 2.5%.

Based on these results:
- according to the recommendations made in the test guidelines, TTP would be regarded as skin sensitizer.
- according to the Regulation (EC) No 1272/2008 on classification, labeling and packaging of substances and mixtures, TTP should be classified as skin sensitizer (Category 1) and labeled as H317: May cause an allergic skin reaction.
- according to the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) of the United Nations (2007), TTP should be classified as skin sensitizer (Category 1).