Registration Dossier

Ecotoxicological information

Sediment toxicity

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Key value for chemical safety assessment

Additional information

Experimental data on the toxicity of tricalcium bis(orthophosphate) to sediment organisms are not available. However, the chemical safety assessment does not indicate the need to investigate further the effects on sediment organisms. Based on the aquatic hazard assessment toxic effects of the substance on terrestrial organisms are not expected. The substance is not expected to bioaccumulate or to be chronically toxic.

On contact with water the substance will dissociate to calcium and phosphate. Both ions are ubiquitous in the environment and are essential micronutrients for organisms. Calcium and phosphorus are vital components of organic structures like biological membranes or the exoskeleton of many sediment organisms. Thus, detrimental effects on sediment organisms are not expected due to the absence of acute aquatic toxicity, the low bioaccumulation potential and the fact that both ions are essential micronutrients.

In the aqueous environment nutrient enrichment (eutrophication) by the addition of phosphate can be a problem in some circumstances. In particular increased phosphate loads to surface waters may be a problem when the conditions are such that P is a growth-limiting factor. The effects of eutrophication can range from ecosystem modifications changes in balance between different species or communities), through to algal blooms and in extreme cases (through decomposition of plant biomass leading to oxygen depletion) collapse of the ecological community.

To avoid such effects, phosphate emissions to surface water via industrial wastewater are regulated in the Council Directive 96/61/EC concerning integrated pollution prevention and control. This states that phosphates have to be taken into account for fixing emission limit values for industrial wastewater. In order to meet the requirements it may be necessary to add a treatment step for phosphate removal from industrial wastewaters before these waters are released to the aqueous environment.

The limitation of phosphorus discharges to surface waters is similarly required by the Urban Waste Water Treatment Directive 1991/271 (EU) which requires the removal of phosphate (P) from municipal waste water in all but very small conurbations, wherever discharge occurs into waters potentially susceptible to eutrophication. The EU Water Framework Directive 2000/60 confirms this obligation, and reinforces it by requiring further treatment, e. g. of smaller conurbations, if this is necessary to achieve water quality status objectives.

Additionally, De Madariaga BM (INIA, 2007) developed a conceptual model and protocol for performing European quantitative eutrophication risk assessments of (poly) phosphates in detergents. In this model, the risk probability for eutrophication occurring in the most sensitive areas of a river basin (lakes, reservoirs, meadow zones, estuaries), is based on the TP (total phosphorous) concentration of the inflow water. The variability observed for similar TP concentrations is the consequence of variations in concentrations of N and/or other nutrients, other ecosystem factors (flow regimes, climate, algal grazer communities...) and other natural variability. The study also covered the implementation of the model and a set of examples based on generic European scenarios as well as a pan European probabilistic estimation covering the diversity observed for the European conditions and enabled a probabilistic risk assessment of eutrophication relating to the use of STPP (sodium tripolyphosphate / pentasodium triphosphate) in detergents. The scientific validity of this methodology was confirmed by the EU scientific committee SCHER (Opinion of 29th November 2007). This model is considered relevant for all phosphates as the ultimate degradation products of polyphosphates (including STPP) in municipal sewage are orthophosphates.