1-(4-trans-Pentylcyclohexyl)-4-propylbenzene

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Justification for read across

Endpoint:Skin Sensitisation

Type of read across:one-to-one

Test Compound (with data):CAS: 174350-05-1

Dossier Compound (without data):CAS:82991-48-8

The read across is based on the following similarity measures:

(1) Chemical similarity
The test compound (CAS: 174350-05-1) provides all main chemical features present in the dossier compound (CAS:82991-48-8). Both substances share typical structural features for liquid crystals, i.e. one phenyl ring coupled via single bond to a cyclohexyl ring.

The test compound shows a flour substitution (n=2) at the phenyl ring that is missing in the dossier compound. In addition the phenyl ring of the test compound shows a para alkoxy substituent while the dossier compound shows a pentyl chain at the same position at the phenyl ring. The cylohexyl ring of both compounds shows a para alkyl substitution (Test Compound: n=3, Dossier Compound: n=5).

Overall, this yields a chemical similarity score of 0.43 (Tanimoto).

(2) Physicochemical similarity
The chemical similarity yields almost identical physicochemical key parameters relevant for bioavailability as listed in the table below.

(3) Similar Effects in Biological Systems
Both compounds have been tested in biological assays for the acute oral toxicity and for mutagenicity in bacteria. The studies were performed according to GLP and the methods applied were fully compliant with the OECD TG.
The LD50 of both compounds exceeds 2000 mg/kg bw/day. Both compounds were not mutagenic in the OECD 471 studies.

The table below lists the similarity measures applied for this read across.

 

Table 1. Comparison of the similarity measures applied for Test and Dossier compound

Assay	Test Compound CAS: 174350-05-1	Dossier Compound CAS: 82991-48-8
Cyclohexyl phenyl core	yes	yes
Terminal substitution at the cyclohexyl ring	propyl	pentyl
Terminal substitution at the phenyl ring	ethoxy	propyl
Liquid crystalline properties	yes	yes
Fluor Substitution at the phenyl ring	yes (n=2)	No
Water solubility	130 µg/L (EU A.6)	46 µg/L (EU A.6)
logP	> 5.7 (OECD 117, EU A.8)	> 6.5 (OECD 117, EU A.8)
Acute Oral Toxicity in Rats	LD50 > 2000 mg/kg bw/d (OECD 423)	LD50 > 5000 mg/kg bw/d (OECD 401)
in vitro Genotoxicity	negative (OECD 471)	negative (OECD 471)
Read Across
Skin Sensitisation	negative (OECD 429)	Negative (Read Across)

Conclusion

The Dossier Compound shows a data gap for Skin Sensitisation; however, a chemical analogue provides data for these endpoints. Both the Dossier Compound and the Test Compound show chemical similarity and almost identical physicochemical parameters leading to similar bioavailability. The response in biological assays was comparable; i.e. the LD50 exceeds 2000 mg/kg bw/d and negative data on mutagenicity in vitro.

Based on these finding it is justified to use the data from the chemical analogue (Skin Sensitisation: negative (GLP, OECD TG 429)) to fill the data gap for the dossier compound.

Migrated from Short description of key information:
This study used for this read across was performed according to GLP and the methods applied are fully compliant with OECD TG 429.

Justification for selection of skin sensitisation endpoint:
For this endpoint a one-to-one read across was performed to a chemical similar compound of the same chemical class with a comparable phys. chem. profile and similar response in biological assays. The relevant study was performed according to GLP and the methods applied are fully compliant with OECD TG 429.

Justification for classification or non-classification

According to the results of the sensitisation test, a classification and labelling is not required for this substance.