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Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Acute Toxicity:

Only non standard studies are available for potassium cyanate for fish, daphnia and algae acute toxicity. Studies with sodium cyanate are also used for read across in some cases to support the sometime non-standard tests available. It is believed that the toxicity of potassium cyanate in water is due to the cyanate ion and not due to the potassium ion.

Fish:

The lowest LC50 identified was 15 mg/L in Salmo gairdneri for potassium cyanate. In a read-across study with the structural analogue sodium cyanate, which was conducted recently according to OECD and EU Guidelines and GLP a LC50 of 94 mg/L was determined in Danio rerio. In conclusion, a NOAEL of 20 mg/L is used for risk assessment as a worst-case figure.

Daphnia:

The lowest LC50 identified was 24 mg/L in Daphnia magna for potassium cyanate. In a read-across study with the structural analogue sodium cyanate, which was conducted recently according to OECD and EU Guidelines and GLP a LC50 of 4.7 mg/L was determined in Daphnia magna. In conclusion, a NOAEL of 18 mg/L is used for risk assessment as a worst-case figure.

Algae:

The LOEC identified was 520 mg/L in Scenedesmus sp. for potassium cyanate. In a read-across study with the structural analogue sodium cyanate, which was conducted recently according to OECD and EU Guidelines and GLP a LC50 of >100 mg/L was determined in a Limit study in Desmodesmus subspicatus. In conclusion, a NOAEL of 520 mg/L is used for risk assessment.

Toxicity to microorganisms:

Based on measured inhibition rates it can be stated that the 3-hour EC20, EC50 and EC80 were higher than 1000 mg/L. The NOEC was determined to be 1000 mg/L.

Long-term toxicity

Daphnia

The long term toxicity to aquatic invertebrates was assessed according to OECD guideline 211, EU method C.20 and OPPTS 850.1300. Daphnids were exposed to the test item under semi-static conditions for 21 days. The nominal concentrations were 0.10 mg/L, 0.25 mg/L, 0.50 mg/L, 1.0 mg/L, 2.5 mg/L, 5.0 mg/L and 10 mg/L. The NOEC was 0.1 mg/L and the LOEC was 0.5 mg/L. The EC50 of the test item was calculated to be 0.81 mg/L, EC10 was calculated to be 0.2 mg/L.

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