Dodecaaluminium trimolybdenum dodecaoxide

Toxicity to terrestrial plants

Additional information

No data on toxicity to terrestrial plants 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

For plants, in total 45 individual high quality EC10 values (for 5 different plant species) are selected, ranging from 4 mg added Mo/kg dw (for oilseed rape in soil 10 and red clover in soil 9) to 3476 mg added Mo/kg dw (for ryegrass in soil 1).

All data are based on added measured Mo concentrations in soil.

For 5 dose-response-curves, no reliable EC10 or NOEC could be derived because a significant effect was already seen at the lowest dose tested (oilseed rape and red clover shoot yield in soil 7, tomato shoot yield in soil 10 and barley root elongation in soils 2 and 10).

For the aged soils (soil 4, 5 and 6), the comparison of Mo in freshly spiked and 11 -month aged soils show that long-term equilibration of Mo in soil generally decreases its toxicity in plants. Only in one case (out of 12 cases) there was an effect at a lower dose in the aged soil (oilseed rape in soil 4). The results of the toxicity in aged soils is used to determine a leaching/ageing factor to correct for the effect of spiking on the toxicity of Mo in soil organisms.

Author, year	Species	Endpoint	Value [mg Mo/kg soil dw]
Micò et al., 2010	Lolium perenne	21 d EC10	14 - 3476
Micò et al., 2010	Hordeum vulgare	21 d EC10	3 - 433
Kàdàr, 1995	Zea mays	4 d EC10	20
Micò et al., 2010	Brassica napus	21 d EC10	4 - 2844
Micò et al., 2010	Trifolium pratense	21 d EC10	0.4 - 1502
Micò et al., 2010	Lycopersicon esculentum	21 d EC10	3 - 1575
Biacs et al., 1995	Daucus carota	6 mo EC10	>= 114
Nyàrai-Harvàth, 1997	Pisum sativum	3 mo EC10	>= 114