Potassium dicyanoargentate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

calculation (if not (Q)SAR)

Remarks:

estimated by calculation

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Remarks:

Predicted based on mixture toxicity assessment, acceptable with restrictions

Principles of method if other than guideline:

The acute toxicity of silver cyanide compounds is predicted based on information about the acute toxicity of the individual components (i.e.silver, and cyanide). Information on the toxicity of the different components is combined with predictions of the speciation of the precious metal cyanide compound in typical ecotoxicity test media.

All chemical speciation calculations were performed using VisualMINTEQ (Version 3.0). Measured Daphnia test results for potassium dicyanoargentate have been used to validate the predictions from the mixture toxicity assessment. Comparison of the measured and modelled values indicates that the modelling approach is reliable for silver cyanide substances.

GLP compliance:

no

Test organisms (species):

Pimephales promelas

Details on test organisms:

EC50 values were predicted for Oncorhynchus mykiss and Pimephales promelas based on acute toxicity data for silver and cyanide, as these species are the most sensitive to both silver and cyanide. The lowest predicted EC50 value, for Pimephales promelas, is used to fill the acute toxicity to fish endpoint for potassium dicyanoargentate.

Total exposure duration:

96 h

Details on test conditions:

Predictions for potassium dicyanoargentate are based on the most sensitive acute toxicity data for silver and cyanide.

For cyanide, the most sensitive species tested was Oncorhynchus mykiss, with acute LC50 values ranging from 27 to 97 µg (CN-) l-1. The geometric mean of acute LC50 values for Oncorhynchus mykiss is 57 µg (CN-) l-1. Data are also available for the toxicity of cyanide to Pimephales promelas, which was slightly less sensitive then Oncorhynchus mykiss. Thirty-five tests on this species were reported, with LC50 values ranging from 79 to 339 µg (CN-) l-1, and a geometric mean of 137 µg (CN-) l-1.

For silver, the most sensitive fish species in acute toxicity tests was Pimephales promelas, with a 96 hour EC50 value of 1.2 µg l-1 dissolved silver. Data are also available for the toxicity of silver to Oncorhynchus mykiss, which was found to be slightly less sensitive with an LC50 value of 3.3 µg l-1 dissolved silver. Details of the water chemistry of these tests were not available to enable calculation of the test endpoints on a free Ag+ basis. In the absence of this information the fraction of dissolved silver which was present as free Ag+ in the critical Daphnia test (0.44) was also assumed for these tests.

Mixture toxicity has been assessed according to the “Concentration Addition” method. This method considers the relative risk, or pressure, exerted by each potentially toxic component on the basis of the risk characterisation ratio, and the risk characterisation ratios for each of the individual components are added together to determine the overall risk

For potassium dicyanoargentate silver is likely to provide the dominant contribution to the overall toxicity, but cyanide may also contribute to a lesser extent.

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

3.3 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: The LC50 value was predicted based on acute toxicity data for silver and cyanide and speciation predictions for potassium dicyanoargentate

Details on results:

The LC50 for potassium dicyanoargentate was predicted based on acute toxicity data for silver and cyanide and speciation predictions for potassium dicyanoargentate. The results of the mixture toxicity assessment were validated based on measured results for Daphnia. The modelled and measured EC50 values for toxicity of potassium dicyanoargentate to Daphnia are in excellent agreement (0.0257 mg/L modelled, 0.022 mg/L measured) and therefore the predictions for acute toxicity to fish are considered to be reliable.

Validity criteria fulfilled:

not applicable

Conclusions:

The LC50 for potassium dicyanoargentate is predicted to be 3.3 mg/L. Acute toxicity to fish is predicted using a mixture toxicity approach, based on acute ecotoxicity data for silver and cyanide and speciation predictions for potassium dicyanoargentate.

Executive summary:

In order to minimise the need for animal testing a calculation approach has been used in order to determine the acute toxicity of potassium dicyanoargentate. As a large body of ecotoxicity data is already available for silver and cyanide, the toxicity of potassium dicyanorgentate is predicted based on the measured values for silver and cyanide and the speciation of the precious metal cyanide substance in the test solution.

The results of the mixture toxicity assessment were validated using measured results for Daphnia. The modelled and measured EC50 values for toxicity of potassium dicyanoargentate to Daphnia are in excellent agreement (0.0257 mg/L modelled, 0.022 mg/L measured) and therefore the predictions for acute toxicity to fish are considered to be reliable.

Description of key information

The LC50 for potassium dicyanoargentate is predicted to be 3.3 mg/L. Acute toxicity to fish is predicted using  a mixture toxicity approach, based on acute ecotoxicity data for silver and cyanide and speciation predictions for potassium dicyanoargentate.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

3.3 mg/L

Additional information

In order to minimise the need for animal testing a calculation approach has been used in order to determine the acute toxicity of potassium dicyanoargentate. As a large body of ecotoxicity data is already available for silver and cyanide, the toxicity of potassium dicyanoargentate is predicted based on the measured values for silver and cyanide and the speciation of the precious metal cyanide substance in the test solution.

The results of the mixture toxicity assessment were validated using measured results for Daphnia. The modelled and measured EC50 values for toxicity of potassium dicyanoargentate to Daphnia are in excellent agreement (0.0257 mg/L modelled, 0.022 mg/L measured) and therefore the predictions for acute toxicity to fish are considered to be reliable.