2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane

Carcinogenicity

Description of key information

In a study designed to investigate the dermal oncogenic potential of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Union Carbide Corporation, 1979), in the group of mice treated with the test substance, four mice developed squamous cell carcinomas of the skin of the treatment area. The negative and positive controls gave appropriate results. Due to the limitations of the study design the results contribute to a weight of evidence for carcinogenicity of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

Key value for chemical safety assessment

Carcinogenicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEL

25

Study duration:

chronic

Species:

mouse

Justification for classification or non-classification

Based on the available data from the mouse dermal carcinogenicity study and positive in vitro genetic toxicity studies, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane requires classification for carcinogenicity as Category 2, H351: Suspected of causing cancer, according to Regulation (EC) 1272/2008.

Additional information

In a study designed to investigate the dermal oncogenic potential (Union Carbide Corporation, 1979), 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane was assessed by applying 25µl aliquots of undiluted test substance to the shaved skin of 40 male C3H/HeJ mice. A negative control group of a similar size received the same volume of acetone only and a positive control group received 0.1% methylcholanthrene in acetone. All substances were applied to the skin of the back three times weekly until the death of the animals. In the group of mice treated with the test substance, four mice developed squamous cell carcinomas of the skin of the treatment area. Although two further mice were noted with subcutaneous tumours (a fibrosarcoma and a myxofibrosarcoma) outside of the treatment area these were considered not to be attributable to treatment. No skin neoplasms were observed in the group treated with acetone although two mice had subcutaneous sarcomas (fibrosarcoma and lymphosarcoma) outside of the treatment area. Both of these sarcomas were unusual and had never been seen in similarly treated control mice in the laboratory concerned. The positive control group had 39 animals with skin tumours including 33 with confirmed squamous cell carcinomas. No significant signs of irritation were observed in any group. Silicone A-186 was considered by the study authors to be tumorigenic when applied to the skin of C3H mice under the conditions of this study.

Justification for selection of carcinogenicity via dermal route endpoint:
The study was conducted according to a scientific principle and adds to the weight of evidence.

Carcinogenicity: via dermal route (target organ): other: skin