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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

For assessing the aquatic hazard of CdZnS, reference has been made to ecotoxicity data obtained by standard testing on CdTe, a sparingly soluble  Cd-compound. Transformation dissolution data demonstrate that the solubility of Cd in CdZnS is even much lower than the solubility of Cd from CdTe (>16-50 times lower solubility of Cd in CdZnS, as compared to solubility in CdTe). The ecotoxicity of CdTe was therefore used as a worst case for the ecotoxicity of CdZnS. 
The influence of CdTe on the respiration rate of activated sludge was investigated after a contact time of 3 hours. The EC50 derived was > 1 g CdTe/L. However, as Cd2+ ion determines ecotoxicity, the PNEC deriviation will be based on the Cd 2+ ion as determined in the RA (2008).

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
100 mg/L

Additional information

Under the conditions of the activated sludge respiration inhibition test CdTe was not toxic to waste water (activated sludge) bacteria at or below a loading rate of 100 mg/L (NOEC). The EC50 derived was > 1 g CdTe/L. However, as Cd2+ ion determines ecotoxicity, the PNEC deriviation for STP will be based on the Cd 2+ ion as determined in the RA (2008).