Lithium

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

In accordance with column 2 of REACH Regulation 1907/2006/EC, Annex VII, section 8.3. an in vivo sensitisation test does not need to be conducted if the available information indicates that the substance should be or is classified as corrosive to the skin. Lithium metal is corrosive and is labelled as such as it forms a strong base (lithium hydroxide) in contact with water or moist skin. Thus, results of a sensitisation study with lithium metal will not be scientifically valid because of local tissue damage due to corrosiveness as well as animal welfare reasons. For estimation of the sensitisation potential of lithium / lithium ions studies with lithium chloride and lithium carbonate were used in a read-across approach. Based on the results obtained in these studies, lithium is not expected to have a skin sensitisation potential.

Sensitisation study with lithium chloride

A skin sensitisation test in Hartley guinea pigs was performed according to OECD 406 and EU method B.6. Lithium chloride solution (0.5 mL undiluted) was applied to the right shoulder of each of ten male Hartley guinea pigs for a six hour exposure period at weekly intervals for three weeks. 14 days after the third induction treatment, the animals were challenged at a virgin skin site. The concentration of the test material chosen for challenge of the test group was the undiluted test material, which was the highest non-irritating concentration as determined during the range-finding phase of this study. An additional 10 male naive animals (naive test group) also received 0.5 mL of the undiluted test material for the challenge application. Observations for skin reactions were recorded approximately 24 hours after unwrapping each induction application and approximately 24 and 48 hours following unwrapping of the challenge application. Body weights were recorded at initiation and termination.

All animals remained healthy and gained weight during the study. No irritation was noted on animals in the test group following the first induction. Cumulative irritation was noted during successive inductions resulting in very faint to strong erythema. No evidence of sensitisation occurred; three test animals of the test group displayed very faint erythema following challenge. Four animals in the challenge control group displayed very faint erythema during challenge. Because reactions were comparable between treated and naive animals at challenge, responses noted were attributed to irritation rather than sensitization reactions.

Under the condition of this study, the test material lithium chloride is judged to be non-sensitizing when topically applied to Hartley guinea pigs.

Based on this result, it can be assumed that lithium is not a sensitiser.

Sensitisation study with lithium carbonate

A skin sensitisation test in Hartley guinea pigs was performed according to OECD 406 and EU method B.6 (Buehler test). Lithium Carbonate Pharmaceutical Grade (0.30 g) was applied undiluted topically to the left shoulders (previously clipped free of hair) of 10 male and 10 female Hartley guinea pigs. The test material was left in contact with the skin for approximately six hours. The animals received three induction treatments one week apart. A concurrent positive control group of 10 animals was treated in a similar manner with DNCB (0.15 % weight/volume). 14 days after the third induction treatment, the animals were challenged with the test material at a virgin skin site. An additional 5 male and 5 female naive animals received 0.30 g of the undiluted test material (challenge control group). The positive control group was challenged with DNCB. Observations for skin reactions were recorded at initiation and termination. All animals remained healthy and gained weight during the study. No skin reactions were noted on any of the test or challenge control animals at any time during the study. Animals in the positive control group had slight erythema and edema following the initial induction application and all but one had well defined to moderate erythema and slight to mild edema following challenge. Under the conditions of this study, the test material is non-sensitising when topically applied to Hartley guinea pigs.

Based on this result, it can be assumed that lithium is not a sensitiser.

Migrated from Short description of key information:
In accordance with column 2 of REACH Regulation 1907/2006/EC Annex VII section 8.3, an in vivo sensitisation test does not need to be conducted as lithium is corrosive to skin. For estimation of the sensitisation potential of lithium / lithium ions studies with lithium chloride and lithium carbonate were used in a read-across approach. Based on the results, it can be assumed that lithium is not a skin sensitizer.

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008
The available experimental test data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. Based on available data on sensitisation, the test item is not classified according to Regulation (EC) No 1272/2008 (CLP), as amended for the tenth time in Regulation (EU) No 2017/776.