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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Although a bioaccumulation study for yttrium oxide, europium oxide is not considered necessary due to its inorganic nature, its insolubility in water and the low potential to cross biological membranes, a publication on yttrium oxide is present. This shows experimentally that yttrium oxide does not bioaccumulate.

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A bioaccumulation study with yttrium oxide, europium oxide is not considered necessary as the substance is an inorganic water insoluble substance. Therefore, the substance has a low potential to cross biological membranes and (direct and indirect) exposure to the aquatic compartment is unlikely or at least very limited/negligible as the water solubility is very low (<0.663 microgram/L).

However, a publication on the bioaccumulation of yttrium oxide is present. The justification for this analogue approach is described in a report (see section 13 of IUCLID) and in chapter 1.4 of the CSR. The distribution of rare earth elements in the different environmental compartments (water, sediment and biota), and their potential for bioaccumulation in different trophic groups, were studied in a static laboratory experiment using aquatic microcosms. Duckweeds (Sperollela polyrrhiza), daphnids (Daphnia magna), shellfishes (Bellamya aeruginosa) and goldfishes (Carassius auratus) were exposed for 16 days to a rare earth mixed solution (at 1 mg/L) containing cerium trichloride, lanthanum trinitrate, samarium trichloride, digadolinium trioxide and diyttrium trioxide. Rare earth concentrations in water, sediments and biological samples were determined using ICP-AES. All the rare earth elements distributed mainly in sediments (82.01 to 97.64 %), then in water (1.93 to 16.97 %), and for a minor part in biota (0.46 to 1.02 %). None of the rare earth tested showed any bioconcentration effect in goldfish. In shellfish, daphnids and duckweeds, yttrium oxide exhibited bioconcentration coefficients of 27.36, 430.5, and 992.7, respectively. This study shows that yttrium oxide, as well as the other tested Rare Earth Elements, mainly absorbed in sediment and did not bioaccumulate in aquatic organisms (BCF<2000).