Registration Dossier

Administrative data

Description of key information

In a GLP-compliant Buehler-Test according to OECD Guideline 406 in guinea pigs Triisobutyl phosphate was sensitising.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to
OECD Guideline 406 (Skin Sensitisation)
according to
EU Method B.6 (Skin Sensitisation)
according to
EPA OPP 81-6 (Skin Sensitisation)
GLP compliance:
Type of study:
Buehler test
Justification for non-LLNA method:
study was conducted before implementation of LLNA
Specific details on test material used for the study:
- Name of test material: Etingal
- Physical state: liquid, achromatic
- Lot/batch No.: MG-94-37
- Storage condition of test material: room temperature
- Substance number: 94/261
guinea pig
other: Pirbright White, Dunkin Hartley Crl: (HA)BR (SPF)
Details on test animals and environmental conditions:
- Source: Charles River GmbH - Wiga, Sulzfeld, FRG
- Age at study initiation: Young adult animals
- Weight at study initiation: 313 - 388 g
- Housing: No. of animals per cage: 5. Type of cage: Makrolon, type IV. Bedding: Granulat Typ 3/4 (staubfrei); SSNIFF
- Diet (ad libitum): Kliba Labordiät 341 (Kaninchen- Meerschweinchen-Haltungsdiät)
- Water (ad libitum): tap water; about 2 g of ascorbic acid per 10 l water was added to the drinking water twice a week
- Acclimation period: 8 days before the beginning of the study in the laboratory for dermal toxicity

- Temperature (°C): 20 - 24°C
- Humidity (%): 30 - 70% .
- Air changes (per hr): not specified
- Photoperiod (hrs dark / hrs light): 12h light (6.00 a.m. - 6.00 p.m.) 12 h darkness (6.00 p.m. - 6.00 a.m.)

Not specified
epicutaneous, occlusive
other: olive oil
Concentration / amount:
75 % / 0.5 mL
3 times (once per week) for 6 hours, respectively
epicutaneous, occlusive
other: olive oil
Concentration / amount:
50 % / 0.5 mL
6 hours
No. of animals per dose:
Pretest: 4
Main test;
- control group: 10
- test group: 20
Details on study design:
2 x 2 cm gauze patches were applied to the skin of the flanks under an occlusive dressing (the bandage consists of rubberized linenpatches 4 x 4 cm
from Russka, test patch of Idealbinde 5 x 5 cm from Pfälzische Verbandstoff-Fabrik, and Fixomull® Stretch (adhesive fleece) from Beiersdorf AG). 0.5 mL of the test substance or test substance preparations were exposed to the animals.

Duration of exposure: 6 hours
Site of application: right and left flank
Application frequency: 2 times (one application per week) on the same application area
Number of test animals: 4 per test concentration
Readings: 24 and 48 h after the removal of the patch
Assessment of skin findings: according to Draize, J.H. (1959)

- Exposure period: 6 hours
- Test groups: 20 animals
- Control group: 10 animals
- Site: anterior left flank
- Frequency of applications: 3 times (one application per week; days 0, 7 and 14) on the same application area
- Concentrations: 75%

- Day(s) of challenge: 14 days after the third induction
- Exposure period: 6 hours
- Test groups: 20 animals
- Control group: 10 animals
- Site: Substance formulation: anterior right flank. Vehicle: posterior right flank
- Concentrations: 50%
- Evaluation (hr after challenge): 24 and 48 h after the removal of the patch
Challenge controls:
Treatment of the test group and of control group 1 with the test substance formulation. Additionally olive oil DAB 10 was applied as a vehicle. Control group 2 only received olive oil DAB 10.
Positive control substance(s):
Positive control results:
The positive control showed that the test system was able to detect sensitizing compounds under laboratory conditions chosen.
1st reading
Hours after challenge:
test group
Dose level:
0.5 ml
No. with + reactions:
Total no. in group:
Clinical observations:
very slight erythema
Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

In the key study, Triisobutyl phosphate was tested for its sensitizing effect on the skin of the guinea pig in the Beuhler test according to OECD guideline 406 (BASF, 1989).

After the 1st, 2nd or 3rd induction with 75% test substance preparations very slight to well-defined signs of irritation could be observed in test group animals.

The challenge with a 50% test substance preparation caused very slight to well-defined skin reactions in test group animals.

Macroscopic examination revealed that the cause of death in two animals was not substance-related.

Based on the results of the study under the test conditions chosen and applying the evaluation criteria it was concluded that Triisobutyl phosphate has a sensitizing effect on the skin of the guinea pig in the Buehler Test.

Supportingly, Triisobutyl phosphate was tested in a Guinea pig maximisation test (Hoechst, 1989). Intradermal induction was carried out with 0.05% w/w Triisobutyl phosphate in paraffin DAB, while for dermal induction and dermal challenge, 4% w/wTriisobutyl phosphate in white Vaseline DAB was used. The challenge resulted in a reaction in 9 of the 10 animals. Furthermore, Triisobutyl phosphate was tested in guinea pigs (Eastman Kodak, 1986). The observed score at the 48 hours reading was 2.5.

Additionally, an in vitro skin sensitization test battery was conducted (BASF, 2013). The test substance has been assessed in vitro methods addressing major steps of the sensitization process. The test evaluation of the Direct Peptide Reactivity Assay (DPRA, addresses peptide binding potential), the LuSens Assay (addresses the keratinocyte activation potential) and the Myeloid U937 Skin Sensitization Test (MUSST, addresses dendritic cell line activation potential) was negative. An additional in vitro skin sensitization test, the human cell line activation test (h-CLAT, addresses dendritic cell line activation potential), showed positive results. In conclusion, the test substance is not predicted to be a skin sensitizer in the in vitro skin sensitization test battery. However, because of the positive results observed in animal studies, the test substance is considered to be a skin sensitizer.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. Based on the effects as observed in the Buehler test, the substance is considered to be classified as a skin sensitizer (Cat. 1B) under Regulation (EC) No. 1272/2008, as amended for the tenth time in Regulation (EC) No. 2017/776.