1-Butoxy-4-[4-(trans-4-ethylcyclohexyl)-1-cyclohexen-1-yl]-2,3-difluorobenzene

Endpoint summary

Description of key information

In this assay (OECD 429), the substance showed no increase in the SI values indicating that the substance is not a skin sensitiser.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Mar 06, 2020 - May 26, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This substance was notified under MEP Order No. 7 in China as regular registration of a new chemical substance. The regular registration under MEP Order No. 7 does not accept in vitro alternative methods to access skin sensitization but requires in vivo data. Therefore, the OECD 429 assay was performed to comply with this regulatory requirement.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Inbred, SPF-Quality
- Age at study initiation: 10 weeks
- Weight at study initiation: Pre-test and Main test: 20.1 to 24.0 g
- Housing: grouped per dose
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C
- Humidity (%): 39 - 43 %
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: day 1 To: day 6

Vehicle:

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

Concentration:

5, 10, and 25% (w/w)

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
Two test item concentrations were tested; a 10% and 25% concentration. The highest
concentration was the highest concentration that could be prepared homogeneously.

At a 10 and 25% test item concentration, no signs of systemic toxicity were noted and only
very slight irritation was observed in the 25% test item group. Therefore, a 25% concentration
was selected as highest concentration for the main study.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: OECD 429
- Criteria used to consider a positive response: Stimulation index > 3

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

Standard statistical methods have been applied for data processing.

Positive control results:

Conc. SI
0%: 1.0
5% 1.3
10% 3.4
25% 5.5

Key result

Parameter:

SI

Value:

0.8

Test group / Remarks:

Test Group: 5% in AOO

Key result

Parameter:

SI

Value:

0.8

Test group / Remarks:

Test Group: 10% in AOO

Key result

Parameter:

SI

Value:

0.6

Test group / Remarks:

Test Group: 25% in AOO

Calculation of Stimulation Indices per Dose Group

Test item concentration	Group Calculation
	Mean DPM per animal (2 lymph nodes)	SD	S.I.
AOO (Vehicle Control)	310	49	1.0
5 % Test Item in AOO	262	47	0.8
10 % Test Item in AOO	260	43	0.1
35 % Test Item in AOO	190	39	0.1

Interpretation of results:

GHS criteria not met

Conclusions:

The test item would not be regarded as a skin sensitizer according to the recommendations made in the test guidelines. The test item does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2017) (including all amendments) and the Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).

Executive summary:

Objective

The objective of this study was to evaluate whether the test material induces skin sensitization in mice after three epidermal exposures of the animals under the conditions described in this report.

Study Design

The study was carried out based on the guidelines described in:

• OECD, Section 4, Health Effects, No.429 (2010).

• EC No 640/2012, Part B: "Skin Sensitization: Local Lymph Node Assay".

• EPA, OPPTS 870.2600 (2003) “Skin Sensitization”.

Test item concentrations selected for the main study were based on the results of a pre-screen test. Based on the results, the highest concentration required according to the guidelines was selected.

In the main study, three experimental groups of five female CBA/J mice were treated with test item concentrations of 5, 10 or 25% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with the vehicle alone (Acetone/Olive Oil, AOO). Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of disintegrations per minute (DPM) and a stimulation index (SI) was subsequently calculated for each group.

Results

All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. Mean DPM/animal values for the experimental groups treated with test item concentrations 5, 10 and 25% were 262, 260 and 190 DPM, respectively. The mean DPM/animal value for the vehicle control group was 310 DPM. The SI values calculated for the test item concentrations 5, 10 and 25% were 0.8, 0.8 and 0.6, respectively. Since there was no indication that the test item elicits a SI = 3 when tested up to 25%, the test material was considered not to be a skin sensitizer. It was established that the EC3 value (the estimated test item concentration that will give a SI =3) (if any) exceeds 25%.

Conclusion

Based on these results, the test material would not be regarded as a skin sensitizer according to the recommendations made in the test guidelines. The test item does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2017) (including all amendments) and the Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).

Reference 2

Endpoint:

skin sensitisation: in vitro

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro skin sensitisation study does not need to be conducted because adequate data from an in vivo skin sensitisation study are available

Justification for type of information:

This substance was notified under MEP Order No. 7 in China as regular registration of a new chemical substance. The regular registration under MEP Order No. 7 does not accept in vitro alternative methods to access skin sensitization but requires in vivo data. Therefore, the OECD 429 assay was performed to comply with this regulatory requirement.

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

The test item does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2017) (including all amendments) and the Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).