Cyclohexyl methacrylate

Endpoint summary

Description of key information

The test substance was sensitising according the results of the murine Local Lymphnode assay.

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:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Winkelmann GmbH, Borchen, FRG
- Age at study initiation: about 8 weeks
- Weight at study initiation: 16.9 g - 20.9 g
- Housing: single housed
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 29 days before the first test substance application

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 30 -70
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

other: acetone

Concentration:

3, 10, 30 %

No. of animals per dose:

6

Details on study design:

The study comprised three treatment groups and a vehicle control group.
Each group consisted of 6 mice. A check for dead or moribund animals was made twice each workday and once on Saturdays, Sundays and on public holidays.
No detailed clinical examination of the individual animals was performed but any obvious signs of systemic toxicity and/or local inflammation at the application sites were noted in the raw data.
Body weights of the individual animals were determined on study day 0 prior to the first application and on day 5 prior to the sacrifice of the animal.
Percutaneous application is simulating dermal contact with the compound which is possible to occur under practical use conditions.
Application volume: 25 µL per ear
Site of application: dorsal part of both ears
Frequency of application: 3 consecutive applications (day 0- day 2) to the same application site

The animals were sacrificed on study day 5 by cervical dislocation.

Immediately after the death of each animal a circular piece of tissue (diameter 0.8 cm) was punched out of the apical part of each ear. The weight of the pooled punches wasdetermined for each animal.

Immediately after removal of the ear punches the left and right auricular lymph nodes were dissected. The weight of the pooled lymph nodes from both sides was determined for each animal.


A concurrent positive control (reliability check) with a known sensitizer was not included into this study.
Studies using the positive control substance Alpha-Hexylcinnamaldehyde,techn. 85% are performed twice a year in the laboratory in order to show that the test system is able to detect sensitizing compounds under the test conditions chosen.

Key result

Parameter:

other: Lymph node Weight Index

Value:

1.29

Test group / Remarks:

3 % in acetone

Key result

Parameter:

other: Cell count Index

Value:

1.48

Test group / Remarks:

3 % in acetone

Key result

Parameter:

other: Ear Weight Index

Value:

0.95

Test group / Remarks:

3 % in acetone

Parameter:

other: Lymph node Weight Index

Value:

1.47

Test group / Remarks:

10 % in acetone

Parameter:

other: Cell count Index

Value:

1.68

Test group / Remarks:

10 % in acetone

Parameter:

other: Ear Weight Index

Value:

1.05

Test group / Remarks:

10 % in acetone

Parameter:

other: Lymph node Weight Index

Value:

1.78

Test group / Remarks:

30 % in acetone

Parameter:

other: Cell count Index

Value:

1.93

Test group / Remarks:

30 % in acetone

Parameter:

other: Ear Weight Index

Value:

1.18

Test group / Remarks:

30 % in acetone

No signs of systemic toxicity were noticed. The test substance induced a statistically significant and biologically relevant response of the auricular lymph nodes when applied as 3 %, 10 % or 30 % preparations in acetone. The concentration dependent statistically significant increases in ear weights induced by the test substance when applied as 10 % and 30 % preparation indicate some irritation of the ear skins.

In conclusion, Cyclohexylmethacrylat has a skin sensitizing effect in the Murine Local Lymph Node Assay. The threshold concentration for sensitization induction was < 3 % under the test conditions chosen.

Based on the available data, Cyclohexylmethacrylate is a skin sensitizer of strong potency. However, taking into account the observed irritating effects on the ears, and the missing dose-dependency of the lymph node proliferation, the sensitising effect cannot be clearly discriminated from at least partly possible lymph node proliferation based on skin irritancy.

Test group	Treatment	Lymph node Weight Index	Cell count Index	Ear Weight Index
1	Vehicle acetone	1.00	1.00	1.00
2	3 % in acetone	1.29 ##	1.48 ##	0.95
3	10 % in acetone	1.47 ##	1.68 ##	1.05 ##
4	30 % in acetone	1.78 ##	1.93 ##	1.18 ##

The statistical evaluations were performed using the WILCOXON-test (# for p<= 0.05, ## for p<= 0.01

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The sensitising potential of the test substance was assessed in a Murine Local Lymph Node Assay (LLNA) according to OECD guideline 429 (BASF SE, 2004). Test item solution at different concentrations was prepared in the vehicle acetone. 6 female CBA mice per dosing group were treated using test item concentrations of 3, 10, and 30 %. Three consecutive applications were performed with 25 µL per ear each. The animals were sacrificed on study day 5. Immediately after the death of each animal a circular piece of tissue (diameter 0.8 cm) was punched out of the apical part of each ear. The weight of the pooled punches was determined for each animal. Immediately after removal of the ear punches the left and right auricular lymph nodes were dissected. The weight of the pooled lymph nodes from both sides was determined for each animal. No signs of systemic toxicity were noticed. The test substance induced a statistically significant and biologically relevant response of the auricular lymph nodes when applied as 3 %, 10 % or 30 % preparations in acetone. The concentration dependent statistically significant increases in ear weights induced by the test substance when applied as 10 % and 30 % preparation indicate some irritation of the ear skins. In conclusion, Cyclohexylmethacrylat has a skin sensitizing effect in the Murine Local Lymph Node Assay. The threshold concentration for sensitization induction was < 3 % under the test conditions chosen. Based on the available data, Cyclohexylmethacrylate is a skin sensitizer of strong potency. However, taking into account the observed irritating effects on the ears, and the missing dose-dependency of the lymph node proliferation, the sensitising effect cannot be clearly discriminated from at least partly possible lymph node proliferation based on skin irritancy.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008

The available data are reliable and suitable for classification purposes under Regulation 1272/2008. The test substance was sensitising according the results of the murine Local Lymphnode assay. As a result the substance is classified as skin sensitising category 1 (H317 May cause an allergic skin reaction) under Regulation (EC) No 1272/2008, as amended for the tenth time in Regulation (EU) No 2017/776.