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Toxicity to soil macroorganisms except arthropods

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No effects on earthworm (Eisenia fetida) mortality was observed in 9 natural Chinese soils containing up to 71.9 mg/kg dw of soluble Lanthanum ionsIn addition a study  with the closely related cerium dioxide for acute toxicity (14-d) to Eisenia foetida  according to the OECD Guideline 207 and GLP 
No significant effect with respect to survival, weight, behaviour or appearance was observed at the limit dose of 1000 mg/kg dry soil. Therfore it can be concluded that lanthanum oxide is not likely to be toxic to soil macroorganisms.

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Additional information

No information is available for the toxicity to terrestrial soil macroorganisms except arthropods with Lanthanum oxide, but data are available for this endpoint with a mixture of rare earth elements. The structure analogy of the rare earth elements with similar toxicity was described by diverse authors (e.g. Sneller et al. 2000).

No mortality of earthworms (Eisenia fetida) was observed in nine natural Chinese soils within 6 weeks. The total content of Lanthanum, Yttrium, Cerium, Praseodymium and Neodymium in these soils was 18.61 - 162.28 mg/kg d.w., the concentration of Lanthanum was in a range of 4.6 - 71.9 mg La/kg d.w. (corresponding to 5.4 to 84.3 mg Lanthanum oxide/ kg dw). From this, a LC0 > 84.3 mg/kg Lanthanum oxide could be derived. Although the total content of the rare earth elements can not be recalculated to Lanthanum oxide, the more than two fold higher value of the total content of rare earth elements compared to the content of La showed, that the LC0 for Lanthanum chloride, anhydrous is clearly underestimated. Furthermore the bioavailability of lanthanum oxide will probably be lower than that of soluble rare earth compounds.

The closely related substance cerium dioxide has been tested for acute toxicity to Eisenia foetida. The study was carried out according to the OECD Guideline 207 and in compliance with the principles of Good Laboratory Practices.

Worms were exposed to ceriumdioxide mixed with artificial soil at a concentration of 1000 mg/kg of dry soil for a 14-day period.

No significant effect with respect to survival, weight, behaviour or appearance was observed.The NOEC is equal or higher than 1000 mg/kg dry soil. From the weight of evidence of both studies it can be concluded that lanthanum oxide is not likely to have any acute toxic effects on soil maroorganisms such as earthworms.