Butanoic acid, 3-oxo-, methyl ester, reaction products with polypropylene glycol ether with trimethylolpropane (3:1)

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

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

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

- modified LLNA = Local Lymph Node Assay (LLNA) - Integrated Model for Differentiation of Skin reactions (IMDS)): Measurement of cell counts instead of radioactive labeling, ear swelling and ear weights to discriminate between sensitsation and irritation.

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)

Species:

mouse

Strain:

NMRI

Sex:

female

Vehicle:

other: polyethlene glycol 400

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 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.
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 physiiological 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 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)

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.

Positive control results:

Alpha hexyl cinnamic aldehyde (3%, 10% and 30%), checked in regular intervals, shows a clear sensitizing potential in the local lymph node assay (IMDS).

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

Compared to vehicle-treated animals, none of the parameters measured in the test substance treated groups (SFJ 1130 in concentrations of 2 %, 10 % and 50 % in PEG 400, i.e. cell counts and weights of the draining lymph nodes, ear weights and ear swelling reached or exceeded the 'positive levels' defined for this assay. Thus the "positive level", which is 1.4 for the cell count index, was never reached or exceeded in any dose group.

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: modified LLNA; measurement of cell counts instead of radioactive labeling

Compared to vehicle-treated animals, none of the parameters measured in the substance treated groups, i.e. cell counts and weights of the draining lymph nodes, ear weights and ear swelling, reached or exceeded the "positive levels" defined for this assay. These results show that there is no indication for a skin sensitizing effect after administration of a concentration up to and including 50 % test item in this test system.

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

These results are verified by the comparison with the results of the positive control group (Alpha Hexyl Cinnamic Aldehyde).

Interpretation of results:

other: no sensitizing potential; no indication for non-specific (irritant) activation

Executive summary:

The test item showed no skin sensitizing potential in the modified Local Lymph Node Assay (IMDS) in female NMRI mice (OECD 429) after dermal application of up to and including a 50 % concentration. Additionally, no indication for a non-specific (irritant) potential was detected. Therefore, the concentration of 50 % turned out to be the NOEL for the parameters investigated in this study with respect to skin sensitization.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Migrated from Short description of key information:
The test item showed no skin sensitizing potential in the modified Local Lymph Node Assay (IMDS) in female NMRI mice (OECD 429) after dermal application of up to and including a 50 % concentration. Additionally, no indication for a non-specific (irritant) potential was detected. Therefore, the concentration of 50 % turned out to be the NOEL for the parameters investigated in this study with respect to skin sensitization.

Justification for selection of skin sensitisation endpoint:
only one study available