Registration Dossier

Ecotoxicological information

Long-term toxicity to aquatic invertebrates

Currently viewing:

Administrative data

Link to relevant study record(s)

Referenceopen allclose all

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented, peer reviewed non-GLP study
Principles of method if other than guideline:
The role of ambient calcium concentrations on survival, moulting, growth and egg production was assessed in the cladoceran Daphnia magna.
GLP compliance:
no
Executive summary:

A threshold for survival was found in the range 0.1–0.5 mg Ca l–1, even when ionic strength of the medium was kept constant. Accumulated length and length specific dry weight was retarded at low Ca (0.5–1.0 mg Ca l–1) at food concentrations above incipient limiting level. For lower food levels, the effect of Ca on growth was less clear. The effect of low Ca on growth rate was most manifest during the first days after hatching, reflecting the higher Ca demands of the early juveniles. Age-specific egg production was strongly reduced at Ca concentrations.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented, peer reviewed non-GLP study
Principles of method if other than guideline:
The influence of environmental calcium on phosphorus biokinetics and regulation in Daphnia magna was examined.
GLP compliance:
no
Executive summary:

When the Ca concentration in culturing media increased from 0.5 to 200 mg l–1, the specific P content ofD. magnafeeding on P-sufficient algae decreased significantly from 1.43 to 1.05% of dry weight. There was a significant negative relationship between the specific Ca and P contents (% dry wt) of daphnids. However, measured biokinetic parameters, including the assimilation efficiency (AE) of dietary P, the weight-specific ingestion rate (IR), the uptake of inorganic P from water, and the efflux rate constant (ke) of P, were similar over the wide range of Ca concentrations, with some exceptions at the lowest Ca level (0.5 mg l–1). Diet was the dominant source of P for daphnids, and only 1 to 2% of P was incorporated from water, based on the biokinetic calculation. With the elevation of the Ca level from 0.5 to 200 mg l–1, the proportion of P lost through molting byD. magnafeeding on P-sufficient diets increased 2.5-fold, whereas the dissolved release decreased 1.9-fold. P released into the dissolved phase is readily re-utilized by primary producers, while P contained within the shed molts sinks out of the epilimnion and becomes at least temporarily unavailable to primary producers; thus, the effects of Ca on molting and dissolved release have significant implications for P cycling in freshwater lakes. Our results suggest that the availability of P to primary producers can be reduced by sedimentation of P-rich daphnid molts in high-Ca lakes, and Ca concentration in the water needs to be considered in studying the stoichiometric regulation of P in freshwater cladocerans.

Description of key information

Key value for chemical safety assessment

Additional information

Experimental data on the chronic toxicity of tricalcium bis(orthophosphate) are not available. Tricalcium bis(orthophosphate) is not acutely toxic to aquatic organisms and has no potential to bioaccumulate in organisms. Therefore a long-term toxicity of the substance to aquatic invertebrates is not anticipated. On contact with water substance will dissociate to phosphate and calcium ions. Both are ubiquitous in the environment and are essential micronutrients for organisms. Calcium and phosphorus are vital components of the exoskeleton of many aquatic invertebrates. Thus, growth and reproduction are affected by the availability of these micronutrients (Hessen et al. 2000; Tan and Wang, 2009).

A chronic toxicity of the substance is not anticipated due to the lack of acute toxicity and the fact that calcium and phosphate are essential micronutrients for aquatic invertebrates.

References:

Hessen et al. (2000) Calcium limitation in Daphnia magna. Journal of Plankton Research (22), 553–568.

Wang and Tan (2009) Calcium influence on phosphorus regulation in Daphnia magna: implications for phosphorus cycling. Aquatic Biology (5), 1-11