Potassium dicyanoargentate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

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):

other: algae

Details on test organisms:

EC50 values were predicted for algae based on acute toxicity data for silver and cyanide. The predicted EC50 value is used to fill the acute toxicity to aquatic algae 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.

Relatively few tests of the toxicity of cyanide to algae are available and in the majority of cases have not been performed in accordance with current standard testing guidelines. As a result of this there is considerable variation in the duration of the tests reported, between 24 hours and 32 days, and no data are available for the common test species Pseudokirchneriella subcapitata. The most sensitive result reported is for a 24 hour test with a Chlorococcales species which resulted in an EC50 value of 45 µg (CN-) l-1. Similar sensitivity has also been reported for the marine species Nitzschia closterium in a 72 hour test (EC50 57 µg (CN-) l-1). Tests on three other species indicated low sensitivity to free cyanide.
A 72 hour ErC50 value of 9.7 µg l-1 dissolved silver was reported for a test on Pseudokirchneriella subcapitata. Other studies have reported lower sensitivity for two Chlorella species (10 to 100 µg l-1), in tests of unknown duration, and for the saltwater alga Skeletonema costatum (130 µg l-1).

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:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: The EC50 value was predicted based on acute toxicity data for silver and cyanide and speciation predictions for potassium dicyanoargentate.Toxicity tests used ranged from 24-72 hours.

Details on results:

The EC50 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 algae are considered to be reliable.

Validity criteria fulfilled:

not applicable

Conclusions:

The EC50 for potassium dicyanoargentate is predicted to be >100 mg/L. Acute toxicity to algae is predicted using a mixture toxicity approach, based on acute ecotoxicity data for silver and cyanide and speciation predictions for potassium dicyanoargentate.

Executive summary:

A calculation approach has been used in order to determine the acute toxicity of potassium dicyanoargentate to aquatic algae. 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 algae are considered to be reliable. The EC50 for potassium dicyanoargentate is predicted to be >100 mg/L.

Description of key information

The EC50 for potassium dicyanoargentate is predicted to be >100 mg/L. Acute toxicity to algae is predicted using a mixture toxicity approach, based on acute ecotoxicity data for silver and cyanide and speciation predictions for potassium dicyanoargentate. 

Additional information

A calculation approach has been used in order to determine the acute toxicity of potassium dicyanoargentate to aquatic algae. 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 algae are considered to be reliable. The EC50 for potassium dicyanoargentate is predicted to be >100 mg/L.