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Skin sensitisation

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skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
- modified LLNA (IMDS): Measurement of cell counts instead of radioactive labeling. 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 for 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); Ehling G et al., Toxicology 212, 60-68 and 69-79 (2005).
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Chemical structure
Reference substance name:
Esterification products of fatty acids, C16 and C16-18 (even numbered, unsaturated) alkyl and adipic acid with pentaerythritol
EC Number:
Molecular formula:
Not applicable (UVCB substance)
Esterification products of fatty acids, C16 and C16-18 (even numbered, unsaturated) alkyl and adipic acid with pentaerythritol
Test material form:
Specific details on test material used for the study:
Stability in vehicle analytically confirmed.

In vivo test system

Test animals

Details on test animals and environmental conditions:
- Strain: Hsd Win: NMRI (SPF-bred)
- Source: Harlan Nederland, 5960 AD Horst, Netherland
- Age at study initiation: 9 weeks
- Weight at study initiation: 27-34 g
- Housing: During the study period the animals were single-housed in Makrolon type II cages.
- Diet and water: ad libitum
- Acclimation period: at least 6 days

- 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)

acetone/olive oil (4:1 v/v)
0 (vehicle control), 2, 10, 50 %
No. of animals per dose:
Details on study design:
The test item was formulated once at day 1 of the study in acetone/olive oil. The formulation was 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. For negative control a dose group treated only with the vehicle acetone /olive oil in the above described manner was used.
The animals were anaesthetized by inhalation of carbon dioxide and sacrificed one day after the last application (d4). The appropriate organs were then removed. Lymphatic organs (the auricular lymph nodes) were transferred into physiological saline (PBS).
- weight of lymph nodes
- cell counts in lymph nodes
- stimulation index (calculated by dividing the absolute number of weight or cell counts of the substance treated lymph nodes by the vehicle treated ones)
- ear swelling
- ear weight
- body weights
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
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 Scheffels 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, checked in regular intervals, showed a clear sensitizing potential in the local lymph node assay (IMDS).

In vivo (LLNA)

Remarks on result:
other: The "positive level", which is 1.4 for the cell count index, was never reached or exceeded in any dose group. Cell count index (test item concentration): 1.00 (0 %) / 0.76 (2 %) / 0.84 (10 %) / 0.74 (50 %).
(modified LLNA; measurement of cell counts instead of radioactive labeling)

Any other information on results incl. tables

Compared to vehicle-treated animals, none of the other parameters measured in the substance-treated groups, i.e. weights of the draining lymph nodes, ear weights and ear swelling, reached or exceeded the "positive levels" defined for this assay.

weight index: 1.00 (0 %) / 0.74 (2 %) / 0.92 (10 %) / 0.80 (50 %)

ear swelling: day 1 = 17.25 (0 %) / 17.33 (2 %) / 17.67 (10 %) / 17.58 (50 %); day 4 = 17.75 (0 %) / 17.92 (2 %) / 18.00 (10 %) / 18.67 (50 %); Index day 4 = 1.00 (0 %) / 1.01 (2 %) / 1.01 (10 %) / 1.05 (50 %) ear weight: day 4 = 12.96 (0 %) / 12.65 (2 %) / 13.03 (10 %) / 13.58 (50 %); Index day 4 = 1.00 (0 %) / 0.98 (2 %) / 1.01 (10 %) / 1.05 (50 %). The body weights of the animals were not affected by any treatment. This study does neither point to a non-specific (irritant) nor to a specific irnmunostimulating (sensitizing) potential of the test item.

Applicant's summary and conclusion

Executive summary:

A modified LLNA (IMDS) according to OECD TG 429 was conducted on 6 female NMRI mice per dose group using epicutaneously applied test substance of 0 % (vehicle control), 2 %, 10 % and 50 %. The study does neither point to a non-specific (irritant) nor to a specific immunostimulating (sensitizing) potential of the test item. Therefore, the concentration of 50 % turned out to be the NOEL for the parameters investigated (weight and cell counts of the draining lymph nodes, ear swelling, ear weight) with respect to skin sensitization.