Registration Dossier

Administrative data

Description of key information

In vitro studies on dermal irritation have been conducted on C14, C16, and C18 fatty acid lithium salts. No irritant responses leading to classification were observed.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The irritant/corrosivity properties of free fatty acids are chain length dependent, where the lower carbon chain length < C9 are potentially corrosive, C10 – C12 are potentially irritant and C14 above are expected to be non-irritant (HERA 2002, referencing Briggs et al, 1976 and CIR, 1987). It was expected that similar trends in properties may apply to the lithium salts of fatty acids, so testing was undertaken in a stepwise manner.

Skin irritation studies were undertaken on lithium myristate (C14), which showed negative results. This was supported by results on longer chain length lithium carboxylate salts, a negative outcome in the study on fatty acids C18-(unsaturated) lithium salts. Therefore, as the shortest chain length substance in category was negative, this result was read across the other category members. Further testing on lithium 12-hydroxystearate (C18-OH) and lithium docosanoate (C22) is currently ongoing to confirm this approach.

Key in vitro skin irritation studies on lithium myristate (C14) and Fatty acids C18 (unsaturated) lithium salts gave negative results. Since under REACH, in vitro studies are sufficient for compliance with Annexes VII and VIII, no key in vivo study(ies) has been conducted. A number of in vivo supporting studies in rabbits for skin irritation using greases formulated with lithium 12-hydroxystearate have been conducted. However, since these were performed several decades previously on formulated greases containing other (unknown) performance additives, the results from the in vitro skin irritation tests on isolated C14 and C18 fatty acid lithium salts are considered to be more relevant and indicative of no classification for this endpoint.

References

API (American Petroleum Institute) (2008) Robust Summary of Information on Grease Thickeners (Creation date: October 11, 2003. Printing date: February 20, 2009. Last update: October 20, 2008. Document date: January 11, 2005)

Briggs GB, Doyle RL, Young JA (1976) Safety studies on a series of fatty acids. American Industrial Hygiene Association Journal, vol. 37, pp. 251-252

CIR (Cosmetics Ingredients Review) (1982). Final report of the safety assessment of lithium stearate, aluminum distearate, aluminum stearate, aluminum tristearate, ammonium stearate, calcium stearate, magnesium stearate, potassium stearate, sodium stearate and zinc stearate. Journal of the American college of toxicologists, vol. 1, issue 12, pp. 143-177.

CIR (Cosmetics Ingredients Review) (1987) Final report on the safety assessment of oleic acid, lauric acid, palmitic acid, myristic acid and stearic acid. Journal of American Toxicologists, vol. 6, issue 3, pp. 321-401

HERA (Human Health and Environmental Risk Assessment on ingredients of European household cleaning products) (2002) Fatty Acid Salts (Soap) Environmental and Human Health Risk Assessment

Justification for classification or non-classification

Skin irritation: Not classified. All studies were negative.