Dodecaaluminium trimolybdenum dodecaoxide

Toxicity to aquatic plants other than algae

Additional information

No data on toxicity to aquatic plants other than algae 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

One study on the toxicity of aluminium chloride to duckweed Lemna minor is available which was conducted according to ASTM (Proposed New Standard Practice for Conducting Static Toxicity Tests with Duckweed) and resulted in a 96h-NOEC of > 45.7 mg/L (measured).

Molybdenum

Freshwater:

The toxicity of molybdenum to freshwater aquatic plants was tested by De Schamphelaere et al. (2008) on Lemna minor, resulting in a 7d-ErC10 of 241.5 mg Mo/L.

Marine:

The toxicity to of molybdenum to marine aquatic plants was investigated on the red macroalgae Ceramium tenuicorne by Le Page et al. (2010). As a result, a 7d-ErC10 of 274 mg Mo/L was obtained.

Conclusion

The effect values derived from analogue aluminium compounds are considerably lower than those derived from analogue molybdenum substances. However, these values were not considered for the assessment as it can be assumed that under environmental conditions in aqueous media, aluminium will predominantly be present as insoluble species (Al(OH)₃) and hence, will be present in a bioavailable form only in minor amounts, if at all. Therefore, it was concluded to put forward the most sensitive and reliable results derived from analogue molybdenum compounds for assessment purposes. Still, it should be noted that his represents an unrealistic worst-case scenario as under environmental conditions in aqueous media, the components of the sparingly soluble substance will be present in a bioavailable form only in minor amounts, and hence, the concentration of soluble MoO₄^2-ions released is very low.