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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

For soluble zinc substances, there are many good quality and relevant data for 5 standard species. 
Key data (lowest EC50 values) for zinc ions in freshwater are:
-for Ceriodapnia dubia: 0.413 mg Zn/l (single value) at low pH and low hardness
-for Ceriodapnia dubia: >0.53 mg Zn/l (single value) at low pH and high hardness
-for Ceriodapnia dubia: 0.147 mg Zn/l (geomean value) at neutral/high pH and low hardness
-for Ceriodapnia dubia: 0.228 mg Zn/l (geomean value) at neutral/high pH and high hardness

Key value for chemical safety assessment

Additional information

For soluble zinc substances, there are many good quality and relevant data for 5 standard species. Tests were done according to standard protocol or equivalent.

Data are grouped per species according to

-pH: low (6 -<7) - neutral/high (7 -8.5)

-and hardness: low/medium (<100mg CaCO3/l) and medium/high (>100 mg CaCO3/l).

Ceriodaphnia dubia is for all test conditions the most sensitive species.

Specific ecotoxicity of the substance

The ecotoxicity of the substance is mainly assessed by read across from information obtained on other zinc substances, i.e. ZnCl2 and ZnSO4. On trizinc bis orthophosphate, a specific ecotoxicity test was performed using Daphnia magna, according to OECD 202 standard protocol (Borrmann 2008). The observed 48hrs EC50 of this study was >1.08mg Zn (dissolved)/l, resulting from > 2.34mg Zn total loading/l; the observed NOEC values were 1.08mgZn dissolved and 2.34mg Zn total loading/l .

The average EC50 value observed on Daphnia magna under similar test conditions (neutral-high pH, hardness >100mg CaCO3/l)in the soluble zinc salt studies was 1.052mg Zn (dissolved)/l. Comparison of this latter value with the specific result obtained on the substance suggests that the ecotoxicity of the substance is similar to that of the soluble compounds, when the dissolved zinc fraction is considered. In other words, the validity of read across is confirmed by this specific test on Daphnia magna. It is noted that not all (83%) the zinc was dissolved from the substance in the ecotoxicity test.