Dodecaaluminium trimolybdenum dodecaoxide

Toxicity to soil macroorganisms except arthropods

Description of key information

LC50 (14d) > 1000 mg/kg dw (nominal) for Eisenia foetida (OECD 207)

Additional information

One study is available on the short-term toxicity of aluminium molybdenum oxide to soil macroorganisms. In this study, earthworms (Eisenia fetida) were exposed to the substance in artificial soil at 1000 mg/kg soil dw in a limit test (Chen, 2013). The test was conducted according to national guidelines and OECD 207. No effects were observed in any of the treatments and as a result, an LC50 (14 d) of > 1000 mg/kg soil dw was obtained.

No data on long-term toxicity to soil macroorganisms are available for aluminium molybdenum oxide. However, there are reliable data available for different analogue substances.

The environmental fate pathways and ecotoxicity effects assessments for aluminium metal and aluminium compounds as well as for molybdenum metal and molybdenum compounds is based on the observation that adverse effects to aquatic, soil- and sediment-dwelling organisms are a consequence of exposure to the bioavailable ion, released by the parent compound. The result of this assumption is that the ecotoxicological behaviour will be similar for all soluble aluminium and molybdenum substances used in the presented ecotoxicity tests. As aluminium molybdenum oxide has shown to be only slightly soluble in water (pH 4.5, 7d) and poorly soluble in ecotoxicity test media (pH 7.5-8.5, 96h), it can be assumed that under environmental conditions in aqueous media, the components of the substance will be present in a bioavailable form only in minor amounts (Mo), or hardly, if at all (Al). Within this dossier all available data from soluble and insoluble aluminium and molybdenum substances are taken into account and used for the derivation of ecotoxicological and environmental fate endpoints, based on the aluminium ion and molybdenum ion. All data were pooled and considered as a worst-case assumption for the environment. However, it should be noted that this represents an unrealistic worst-case scenario, as under environmental conditions the concentration of soluble Al³⁺and MoO₄^2-ions released from aluminium molybdenum oxide is negligible (Al) or low (Mo), respectively.

Aluminium

Aluminium, aluminium powders and aluminium oxide are non hazardous (not classified for the environment). Aluminum (Al) is the most commonly occurring metallic element, comprising eight percent of the earth's crust (Press and Siever, 1974) and is therefore found in great abundance in both the terrestrial and sediment environments. Concentrations of 3-8% (30,000-80,000 ppm) are not uncommon. The relative contributions of anthropogenic aluminium to the existing natural pools of aluminium in soils and sediments is very small and therefore not relevant either in terms of added amounts or in terms of toxicity. Based on these exposure considerations additional sediment and/or soil testing is not warranted. More information about exposure based waiving for aluminium in soil and sediments can be found in attached document (White paper on exposure based waiving for Fe and Al in soils and sediments final 15-03-2010. pdf).

Molybdenum

The invertebrate toxicity assays (excluding arthropods) resulted in 20 individual high quality NOEC/EC10 values (for 2 different invertebrates; Enchytraeus crypticus and Eisenia andrei) selected for assessment purposes (van Gestel et al., 2009).

The selected NOEC/EC10 values range from 7,88 mg added Mo/kg for E. andrei in soil 6 to 1661 mg added Mo/kg for E.crypticus in soil 7. All data are based on added measured Mo concentrations in dry weight soil.

For E. crypticus, unbounded NOEC values were observed in soils 1 and 9 (EC10> 2719 and 2816 mg added Mo/kg dw soil respectively).

For the aged soils (soils 4,5 and 6), the comparison of Mo in freshly spiked and 11 -month aged soils show that long-term equilibration of Mo in soils generally decreases its toxicity to invertebrates. Only in one case (out of 6 cases) an effect at a lower dose was observed in the aged soil (E. crypticus in soil 6). The results of the toxicity in aged soils are used to determine a Leaching/Ageing factor to correct for the effect of spiking on the toxicity of Mo in soil organisms.