Dodecaaluminium trimolybdenum dodecaoxide

Endpoint summary

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 chronic terrestrial toxicity 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

To place a proper perspective on the assessment of aluminium in soils, the Executive Summary of the USEPA EcoSSL (Ecological Soil Screening Level) assessment for aluminium is quoted.

 

SUMMARY OF ECO-SSLs FOR ALUMINUM

"Aluminum (Al) is the most commonly occurring metallic element, comprising eight percent of the earth's crust (Press and Siever, 1974). It is a major component of almost all common inorganic soil particles, with the exceptions of quartz sand, chert fragments, and

ferromanganiferous concretions. The typical range of aluminum in soils is from 1 percent to 30 percent (10,000 to 300,000 mg Al kg-1) (Lindsay, 1979 and Dragun, 1988), with naturally

occurring concentrations varying over several orders of magnitude.

EPA recognizes that due to the ubiquitous nature of aluminum, the natural variability of aluminum soil concentrations and the availability of conservative soil screening benchmarks (Efroymson, 1997a; 1997b), aluminum is often identified as a COPC for ecological risk assessments. The commonly used soil screening benchmarks (Efroymson, 1997a; 1997b) are based on laboratory toxicity testing using an aluminum solution that is added to test soils.

Comparisons of total aluminum concentrations in soil samples to soluble aluminum-based screening values are deemed by EPA to be inappropriate. The standard analytical measurement of aluminum in soils under CERCLA contract laboratory procedures (CLP) is total recoverable metal. The available data on the environmental chemistry and toxicity of aluminum in soil to plants, soil invertebrates, mammals and birds as summarized in this document support the following conclusions:

• Total aluminum in soil is not correlated with toxicity to the tested plants and soil invertebrates.

• Aluminum toxicity is associated with soluble aluminum.

• Soluble aluminum and not total aluminum is associated with the uptake and bioaccumulation of aluminum from soils into plants.

• The oral toxicity of aluminum compounds in soil is dependent upon the chemical form (Storer and Nelson, 1968). Insoluble aluminum compounds such as aluminum oxides are considerably less toxic compared to the soluble forms (aluminum chloride, nitrate, acetate, and sulfate). For example, Storer and Nelson (1968) observed no toxicity to the chick at up to 1.6% of the diet as aluminum oxide compared to 80 to 100% mortality in chicks fed soluble forms at 0.5% of the diet.

 

Because the measurement of total aluminum in soils is not considered suitable or reliable for the prediction of potential toxicity and bioaccumulation, an alternative procedure is recommended for screening aluminum in soils. The procedure is intended as a practical approach for determining if aluminum in site soils could pose a potential risk to ecological receptors. This alternative procedure replaces the derivation of numeric Eco-SSL values for aluminum."

References:

Efroymson, R.A., M.E. Will, and G.W. Suter II, 1997a. Toxicological Benchmarks for Potential Contaminants of Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process,ES/ER/TM-126/R2, Oak Ridge National Laboratory, Oak Ridge, TN.

 

Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C. Wooten, 1997b. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants: 1997 Revision, ES/ER/TM-85/R3, Oak Ridge National Laboratory, Oak Ridge, TN.

 

Dragun, 1988.The Soil Chemistry of Hazardous Materials. Hazardous Materials ControlResearch Institute.Silver Spring, MD USA.

 

Lindsay, W.L. 1979. Chemical Equilibria in Soils.John Wiley & Sons.

 

Press, F. and R. Siever. 1974. Earth. W. H. Freeman and Co.

Storer N.L.,Nelson T.S. 1968. The effect of various aluminum compounds on chick performance. Poult Sci.Jan; 47(1):244-7.

Molybdenum

16 studies on the terrestrial toxicity of molybdenum are available. The selected data cover different trophic levels and numerous families (see table).

Taxonomic group	Species
soil macroorganisms	Eisenia Enchytraeus
terrestrial arthropods	Folsomia
terrestrial plants	Lolium Hordeum Zea Brassica Trifolium Lycopersicon Daucus Pisum
birds	Gallus Meleagris

The soil macroorganisms (including terrestrial arthropods) show EC10 values ranging from 7.88 - > 2843 mg Mo/ kg soil dw. In 21 d tests on different mono- and dicotyledonous plants a wide range of EC10 of 0.4 - 2844 mg Mo/ kg soil dw is observed. While 3 month- and 6 month tests on 2 different dicotyledonae have EC10 values of >= 114 mg Mo/kg soil dw as well as microorganism tests (EC10 from 10 - 10000 mg Mo/kg soil dw). In publications, tests on the toxicity to birds are found. While a test with Gallus domesticus had a NOEC of 400 and >= 3 mg Mo/kg diet, another test with Meleagris gallopavo had a NOEC of >= 1 mg Mo/ kg diet.

In the IMOA soils project, a total of 10 topsoils with contrasting properties that may affect the toxicity of Mo in soil were collected and on each of these soils a series of 11 toxicity tests was performed after spiking with Na₂MoO₄(5 plant assays: root elongation for barley and shoot yield for Oilseed rape, Red clover, Ryegrass and Tomato; 3 invertebrate assays: reproduction for Enchytraeus crypticus, Eisenia andrei and Folsomia candida; and 3 microbial assays: nitrification, glucose induced respiration and mineralisation of plant residues). For the invertebrates, ecotoxicity tests were also conducted on an OECD artificial soil.

Additionally, 3 soils were aged outdoors after spiking with sodium molybdate. After 6 and 11 months, subsamples were collected and the 10 ecotoxicity tests (same as above, without barley root elongation assay) were conducted on these soils.

The total number of 113 dose-response curves (i.e. 10 soils * 11 assays + 3 invertebrate assays in OECD control soil) yielded in total 82 useful EC10 and 4 NOEC data (when no reliable EC10 was available because the EC10 was below the lowest tested concentration). For the other 27 dose-response-curves, no reliable EC10 or NOEC could be derived because there was either already an effect at the smallest dose tested (unbounded LOEC, in 5 plant dose-response curves) or no effect at the largest dose tested (unbounded NOEC, in 12 microbial and 10 invertebrate dose-response curves).

All data were based on added mg Mo/kg dw soil.