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Toxicological information

Carcinogenicity

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Description of key information

104 week dermal carcinogenicity study in mice using grease formulated with 7.5%  lithium 12-hydroxystearate, at 50 mg/application. No guideline specified. Lithium 12-hydroxystearate is a member of the lithium salts of C14-C22 fatty acids category. The NOAEL of the grease was 408 – 714 mg/kg bw/day, and 31 – 54 mg/kg bw day for the lithium 12-hydroxystearate.

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:
no adverse effect observed
Study duration:
chronic
Species:
mouse
Quality of whole database:
Limited. The study is taken from a regulatory review documents (US EPA 2011, API 2008) citing a proprietary test. No guideline was stated but a standard procedure was used. Only a summary of the study is available, but as the results are taken from a regulatory document, the data are considered reliable and relevant for use for this endpoint.

Additional information

The substances in the category are considered to be similar on the basis that they have common structures of a lithium ion varying only by the length of the fatty acid chain and the presence of unsaturated and/or hydroxyl functional groups. As a result, it is expected that the substances will have similar, predictable properties. Due to the close structural similarity and the narrow range of carbon chain numbers covered in this category, the carcinogenicity potential is expected to be similar across the category.

A supporting 104-week dermal carcinogenicity study on a lithium complex grease containing 7.5% lithium 12-hydroxystearate and other additives on mice is reported. 50 mg of the grease was applied to the backs of mice twice weekly. Using an average mouse weight of 20 – 35 g (Derelenko, 2008), the NOAEL of the grease was 2857 – 5000 mg/kg/week or 408 - 714 mg/kg bw/day. Correcting this for the lithium 12-hydroxystearate concentration, this gives a dose of 31 – 54 mg/kg bw/day for the lithium salt. This grease was not found to be a carcinogen under the conditions of the test. On the basis of long history of safe use of fatty acid soaps in greases, the substances in the category are not considered to be carcinogens.

References

Derelenko (2008) The toxicologists' Pocket Handbook. 2nd Edition.


Justification for selection of carcinogenicity via dermal route endpoint:
Supporting study conducted on grease formulation containing 7.5% lithium 12-hydroxystearate and other additives.

Justification for classification or non-classification

Not classified for carcinogenicity. No treatment-related increase in tumour incidence.