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Toxicity to terrestrial arthropods

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Description of key information

Test substance is a  mixture of rare earth chloride hexahydrate and rare earth oxides
LC50(72 h) > 3000 mg RE/L for Holotrichia parallela, larvae third stage (filter paper contact test)
NOEC(until adult eclosion) > 3000 mg RE/L for Holotrichia parallela, larvae third stage (prolonged soil test)

Key value for chemical safety assessment

Additional information

No information is available on the toxicity to terrestrial arthropods with Lanthanum oxide, but data are available for this endpoint with a mixture of rare earth chloride hexahydrate and rare earth oxides (Li et al. 2006). The mixture was composed mainly of Cerium, Lanthanum and Praseodymium, a concentration of individual rare earth elements was not given. The structure analogy of the rare earth elements with similar toxicity was described by diverse authors (e.g. Sneller et al. 2000).

The short-term toxicity of a mixture of rare earth chloride hexahydrate and rare earth oxides onHolotrichia parallela(Coleoptera, larvae in the third stage) was tested in a filter paper contact test, yielding a LC50 > 3000 mg RE/L.

In a prolonged soil test groups of larvae (Holotrichia parallela) at the third larval stage were kept in the soil, spiked with mixed rare earth chloride hexahydrate and rare earth oxides. The exposure lasted until adult eclosion. Mortality, pupation and emergence were assessed after the exposure and revealed a NOEC value of > 3000 mg RE/kg soil.

Although the test substance was a mixed rare earth chloride hexahydrate and rare earth oxides with Cerium, Lanthanum and Praseodymium as rare earth elements, the high concentration without effects on mortality, emergence or pupation can be used for the assessment of Lanthanum oxide on terrestrial arthropods.