Cyclohexanone, 4-methoxy-

Endpoint summary

Description of key information

LLNA, in vivo skin sensitization (OECD TG 429, GLP): not sensitizing

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

Study period:

May - June 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Guideline adopted 22 July 2010; 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). The IMDS was validated and published with scientific justification in: Vohr HW et al., Arch. Toxicol., 73, 501-509 (2000); Ehling G et al., Toxicology 212, 60-68 and 69-79 (2005).

Deviations:

yes

Remarks:

modifications: 1. non-radioactive alternative, measuring lymph node cell counts; 2. in addition, measurement of ear swelling and ear weight to discriminate the irritating potential from the sensitizing potential of the test substance

Principles of method if other than guideline:

This study is performed according to OECD TG 429. As stated in OECD TG 429 besides the classical radioactive method ‘other endpoints for assessment of the number of proliferating cells may be employed’ as so-called ‘me-too’ tests, if the required performance standards are fulfilled, they are ‘based on similar scientific principles and measure or predict the same biological or toxic effect’ and they are validated.
Here, an alternative method is used employing the lymph node weight and lymph node cell count to assess proliferation of lymphocytes (IMDS LLNA; Integrated Model for the Differentiation of Skin Reactions). In addition, the acute inflammatory skin reaction is measured by ear weight determination of circular biopsies of the ears and ear thickness measurements on test day 1 and test day 4 to identify skin irritation properties of the test item. It is important to determine if a positive test result is due to the skin irritation potential of the test item or due to its sensitizing properties. Information on validation of the IMDS LLNA 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).
In the IMDS LLNA stimulation indices were calculated for the lymph node cell count, lymph node weight, ear weight and ear thickness by dividing the average values per group of the test item treated animals by the respective vehicle treated ones.
Values above 1.4 (lymph node cell count to identify skin sensitization) or 1.1 (ear weight to identify irritation) are considered positive (these values were fixed empirically during the interlaboratory validation of this method (Ehling et al. 2005a and 2005b)).
- Ehling, G., M. Hecht, A. Heusener, J. Huesler, A. O. Gamer, H. van Loveren, T. Maurer, K. Riecke, L. Ullmann, P. Ulrich, R. Vandebriel, H.-W. Vohr: An European inter-laboratory validation of alternative endpoints of the murine local lymph node assay: First round; Toxicology 212, 60-68 (2005a);
- Ehling, G., M. Hecht, A. Heusener, J. Huesler, A. O. Gamer, H. van Loveren, T. Maurer, K. Riecke, L. Ullmann, P. Ulrich, R. Vandebriel, H.-W. Vohr: An European inter-laboratory validation of alternative endpoints of the murine local lymph node assay: 2nd round; Toxicology 212, 69-79 (2005b).
- Vohr, H.-W., Blümel, J., Blotz, A., Homey, B. and Ahr, H.J. An intra-laboratory validation of IMDS: Discrimination between (Photo) Allergic and (Photo) Irritant Skin Reactions in Mice. Arch. Toxicol., 73, 501-509 (2000).

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

NMRI

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River, Germany
- Age at study initiation: 8 weeks
- Weight at study initiation: 26-32 g
- Housing: 1 animal/cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 6 days

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

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

2, 10 and 50%

No. of animals per dose:

6

Key result

Parameter:

SI

Remarks:

Lymph node Cell count index

Value:

1.09

Variability:

SD +/-41.21%

Test group / Remarks:

2%

Key result

Parameter:

SI

Remarks:

Lymph node Cell count index

Value:

0.9

Variability:

SD +/- 25.65%

Test group / Remarks:

10%

Key result

Parameter:

SI

Remarks:

Lymph node Cell count index

Value:

1.03

Variability:

SD +/-40.37%

Test group / Remarks:

50%

Key result

Parameter:

SI

Remarks:

Lymph node Cell count index

Value:

1

Variability:

SD +/-24.84%

Test group / Remarks:

vehicle control

Interpretation of results:

not sensitising

Conclusions:

The study indicates that the LLNA/IMDS does neither point to a non-specific (irritating) nor to a specific immunostimulating (sensitizing) potential of the test item.

Executive summary:

The modified Local Lymph Node Assay (IMDS) was performed in 2006 on 24 female NMRI mice of the strain Hsd Win:NMRI (6 animals/test item group and 6 control animals) to determine if there is any specific (sensitizing) or non-specific (irritating) stimulating potential of the test item 4-Methoxycyclohexanone.

The study was conducted according to OECD Guideline No. 429, No. 406, EC Guideline 96/54/EC (22nd Adaptation of Guideline 67/548/EEC)/Health Effects Test Guideline, OPPTS 870.2600 (EPA) with the following test item concentrations:
0 (vehicle control), 2, 10 and 50%.
The test item was formulated in acetone/ olive oil 4:1 (A/OO) to yield a solution.
Compared to vehicle treated animals none of the parameter measured, 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.

The results show that the test item (4-Methoxycyclohexanone) has neither an irritating nor a sensitizing potential in mice after dermal application.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the study results for skin sensitization no classification according to Regulation (EC) No. 1272/2008 (CLP), ANNEX I, is warranted.