Phosphonium, tetrabutyl-, (hydrogen difluoride) (1:1)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

- modification: in addition, measurements of ear swelling and ear weight were done to discriminate the irritating potential from the sensitizing potential of the test substance (Integrated Model for the Differentiation of Skin reactions (IMDS))

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

471-140-1

EC Name:

-

Cas Number:

121240-56-0

Molecular formula:

C16H37F2P

IUPAC Name:

hydrogen tetrabutylphosphanium difluoride

Details on test material:

Clear colorless liquid; molecular weight: 298.4; purity: approx. 95 %

In vivo test system

Test animals

Species:

mouse

Strain:

NMRI

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan-Winkelmann GmbH, Borchen, Germany
- Strain: Hsd Win:NMRI
- Age at study initiation: 10 weeks
- Weight at study initiation: 27 - 32 g
- Housing: individual
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +- 2
- Humidity (%): 40 - 70
- Air changes (per hr): about 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Concentration:

0, 1, 3, 10 %

No. of animals per dose:

6

Details on study design:

TREATMENT PREPARATION AND ADMINISTRATION:
The test item in the formulation and the vehicle were applied epicutaneously onto the dorsal part of both ears of the animals. This  treatment was repeated on three consecutive days (d1, d2 and d3). The volume administered was 25µl/ear. The used concentrations were based on the experiences with the test system and the toxic properties of the test substance.

Positive control substance(s):

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

Statistics:

When it was statistically reasonable, the values from treated groups were compared with those from the control group by a one-way analysis of variance (ANOVA) when the variances are considered homogeneous according to a homogeneity testing like Cochran's test. Alternatively, if the variances are considered to be heterogenous (p<=0.05), a non-parametric Kruskal-Wallis test has been used (Kruskal-Wallis ANOVA) at significance levels of 5% . Two sided multiple test procedures were done according to Dunnett or Bonferroni-Holm, respectively. Outlying values in the LN weights were eliminated at a probability level of 99% by Nalimov's method. In addition, for the LLNA/IMDS the smallest significant differentes in the means were calculated by Scheffels method, which according to Sachs can be used for both equal and unequal sample sizes.

Results and discussion

Positive control results:

The local lymph node assay with alpha hexyl cinnamic aldehyde shows a clear sensitizing potential.

In vivo (LLNA)

Results

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

In mice substance concentrations of 1 %, 3 % and 10 % in dimethylformamide did not increase lymph node weights and cell counts. The cell count indices of 0.87, 1.13 and 1.16 are below the critical "positive level" of 1.4, as specified for this method.

Any other information on results incl. tables

The "positive level" of ear swelling which is 2 x 10-2 mm increase, i.e. about 10% of the control values, has not been reached or exceeded in any dose group. A significant increase of ear weight compared to vehicle treated animals was detected in the highest dose group (10 %), indicating an irritating effect. It has to be clarified that the "positive levels" mentioned above are exclusively defined for the NMRI outbred mice used for this study. Such positive limits have to be calculated for each strain of mice individually. The body weights of the animals were not affected by any treatment.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Executive summary:

Tetrabutylphosphoniumhydrogendifluorid has no sensitizing potential in mice after dermal application of up to and including a 10 % concentration. Therefore, the concentration of 10 % turned out to be the NOEL for the parameters investigated in this study with respect to skin sensitization. These results indicate that the test substance can be considered as a non-sensitiser (IMDS = modified LLNA).