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Studies to characterise the terrestrial toxicity of trisodium hydrogen diphosphate are not submitted for the following reasons:

Sodium and potassium pyrophosphates are ionic in nature and therefore dissociate readily into cations and anions in water, sediment and soils. The toxicity of the both the cation and the anion must be addressed. Potassium and sodium cations are essential micronutrients that are ubiquitous in the environment. As such, their uptake is tightly regulated and is therefore not considered to pose a risk for ecotoxicity. The pyrophosphate anion is unstable in aqueous solutions with the degree of instability varying according to pH. In distilled water pyrophosphates will hydrolyse slowly via abiotic mechanisms to inorganic phosphate. In soils a number of different processes can occur; abiotic hydrolysis, biotic degradation (as a result of the action of phosphatases which cleave pyrophosphate into orthophosphate subunits) and assimilation by organisms in the media all resulting in an ultimate breakdown product of orthophosphate.

Furthermore inorganic phosphate fertilizers (containing Na+, K+ and PO43 -ions) are often added to soils to improve soil quality. Given the extensive use of inorganic phosphates as soil fertilizers and the natural occurrence of the ions in the environment it is unlikely that inorganic phosphates of this nature would have a detrimental effect on soil invertebrates and hence toxicity studies are scientifically unjustified.