Ethylidynetrimethanol

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: Guideline study under GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

- modified LLNA(IMDS): Measurements of cell counts instead of radioactive labelling. In addition, measurements of ear swelling and ear weights were done to discriminate the irritating potential from the sensitizing potential of the test substance.

Principles of method if other than guideline:

Modified LLNA (IMDS, Integrated Model for the Differentiation of Skin Reactions). Modifications are authorized in the OECD TG 429 and in the Note of Guidance SWP/2145/00 of the CPMP (2001). Information on validation of IMDS and scientific justification is given in Vohr HW et al., Arch Toxicol 73, 501-509 (2000) and Ehling G et al., Toxicology 212, 60-68 and 69-79 (2005).

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Propylidynetrimethanol

EC Number:

201-074-9

EC Name:

Propylidynetrimethanol

Cas Number:

77-99-6

Molecular formula:

C6H14O3

IUPAC Name:

2-ethyl-2-(hydroxymethyl)propane-1,3-diol

In vivo test system

Test animals

Species:

mouse

Strain:

NMRI

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 8 weeks
- Weight at study initiation: 26-33 g
- Housing: individually
- Diet ad libitum
- Water ad libitum
- Acclimation period:at least 7 days

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

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Remarks:

The stability of the test item in the vehicle was analytically verified for up to 4 days.

Concentration:

0, 2, 10, 50 %

No. of animals per dose:

6

Details on study design:

TREATMENT PREPARATION AND ADMINISTRATION:
The test item in the formulation or 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.
Based on our experiences with this test system and the known properties of the test items the following concentrations were used: 0 (vehicle control) 2%, 10% and 50%.
The animals were anaesthetized by inhalation of carbon dioxide and sacrificed one day after the last application (day 4). The appropriate organs were then removed. Lymphatic organs (the auricular lymph nodes) were transferred into physiological saline (PBS).
Investigations:
-- weight of lymph nodes
-cell counts in lymph nodes
-stimulation index is calculated by dividing the absolute number of weight or cell counts of the substances treated lymph nodes by the vehicle treated ones
- ear swelling
- ear weight
- body weight

Positive control substance(s):

other: Alpha Hexyl Cinnamic Aldehyde formulated in acetone/olive oil (4:1) at concentrations of 3%, 10% and 30% A check of the test system is done in regular intervals.

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 differences in the means were calculated by Scheffe's method, which according to Sachs can be used for both equal and unequal sample sizes.

Results and discussion

Positive control results:

Alpha Hexyl Cinnamic Aldehyde formulated in acetone/olive oil (4:1) at concentrations of 3%, 10% and 30% checked in regular intervals, shows a clear sensitizing potential in the local lymph node assay (IMDS)..

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

Comparable to vehicle treated animals, none of the parameters measured in the test substance groups (Trimethylolpropane concentrations of 2 %, 10 % and 50 % in DMF) i.e. cell counts, weights of the draining lymph nodes , ear weights and ear swelling reached or exceeded the 'positive level' defined for this assay. The cell count indices were determined 0.99, 0.98, 0.96. The critical 'positive level' for this parameter is defined with 1.4.

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Modified LLNA; measurements of cell counts instead of radioactive labelling.

Any other information on results incl. tables

The “positive level” of ear swelling, which is 2x10-2 mm increase about 10% of the control values, has not been reached or exceeded in any dose group. No substance specific effects were determined for ear weights either.

It has to be clarified that the “positive levels” mentioned above are exclusively defined for the NMRI outbreed 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

Conclusions:

not sensitizing

Executive summary:

Trimethylolpropane was tested for sensitization potency using the LLNA/IMDS assay in mice and applying concentrations between 2 and 50 %.

The results show that the test item Trimethylolpropane has no sensitizing potential in mice after dermal application of up to and including a concentration of 50%. No indication for a non-specific (irritant) activation was detected, either. Therefore, the concentration of 50% turned out to be the NOEL for the parameters investigated in this study with respect to skin sensitization (Bayer 2010) .