Hexacalcium hexaoxotris[sulphato(2-)]dialuminate(12-)

Endpoint summary

Additional information

There are no studies available on terrestrial organisms for Ettringite. Due to its chemical nature Ettringite is not stable under natural environmental conditions. The main degradation products are calcium sulfate (dihydrate) with limited solubility resulting in free calcium and sulfate ions and insoluble aluminium hydroxides and insoluble aluminium oxides (at neutral pH range).

Regarding calcium and sulfate ions (based on calcium sulfate):

Given the extensive and continued use of calcium sulfate as a fertiliser and for chemical treatments of soils and its natural occurrence in the environment, it is considered that calcium sulfate would not have a detrimental effect on terrestrial organisms.

The relevant compound to consider with regard to sediment toxicity of Ettringite is aluminium. The environmental chemistry of aluminium is complex and was addressed in several reports and public available sources to date (e.g. Sposito 1995, WHO 1997, EURAS 2007). Aluminium is the most abundant metallicelement in the Earth's crust, with a proportion of around 8% by weight, and the third most abundant of all elements. Due to its reactive nature it does not exist as free elemental metal, rather it occurs in hundreds of different compounds and minerals (e.g. it is contained in the naturally occuring mineral Ettringite). Against the background of this abundance and taking into account available data on the anthropogenic input to the terrestrial environment it is reasoned that aluminium from anthropogenic sources is negligible, both in terms of added amounts as well as in terms of toxicity. Vangheluwe et al (2010) investigated in detail the relative anthropogenic contribution to the existing natural pool. The assessment by Vangheluwe et al (2010) is based on aluminium concentrations for Europe, collected from FOREGS’ geochemical baseline program database (Salminen et al. 2005, http://www.gsf.fi/publ/foregsatlas/index.php), that provides high quality environmental geochemical baseline data for Europe based on samples of stream water, stream sediment, floodplain sediment, soil and humus. For aluminium oxide concentrations of 10.5 % in topsoil, 11.3 % in subsoil, 9.8 % in stream sediment, and 10.1 % in floodplain sediment are reported. The relative importance of anthropogenic contributions of aluminium to the natural background in soil and sediments were evaluated by use of the exposure model EUSES. For the calculation of regional sediment and soil concentrations of aluminium the model was fed with the following emission data. The alumina and primary aluminium production in the European Union is estimated to be about 11.8 million tonnes of aluminium oxide. Aluminium partitioning data (log Kd values) are 5.2 for sediment and 6.62 for suspended particulate matter (SPM). Kd values for aluminium for soil are not available and as a rough estimate the soil Kd was also used for the sediment compartment.

In conclusion, tests on terrestrial toxicity are neither necessary nor appropriate.

 

EURAS (2007) Development of a high quality aquatic ecotoxicity database for Al metal, Al oxide and Al hydroxide.

Sposito (ed) (1995) The environmental chemistry of aluminium. Crc Pr Inc, 480 pp, 2nd edition.

WHO (1997) Aluminium. Environmental Health Criteria 194.

Vangheluwe; M., Vercaigne,, Vandenbroele, M., Shtiza, A., Heijerick, D. (2010) White Paper on exposure based waiving for iron and aluminium in soil and sediments. Arche, Assessing Risks of Chemicals, 58 pp.