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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

ZINC DILAURATE: 
Acute toxicity of zinc dilaurate to the waterflea Daphnia magna at pH 7.8: the EC50 was not reached up to 10 mg zinc dilaurate/L. Thus, acute toxicity of zinc dilaurate to aquatic invertebrates is above the water solubility limit ranging from 5.2 to 6.4 mg/lL.
For a comprehensive overview of the ecotoxicity of zinc, see the hazard assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 (see Appendix 1 of the CSR).
ZINC:
Key data (lowest EC50 values) 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

ZINC DILAURATE:

The toxicity of zinc dilaurate to Daphnia magna is above the water solubility limit ranging from 5.2 to 6.4 mg/L; an EC50 was not reached up to 10 mg zinc dilaurate/L at pH 7.8. Regarding the acute toxicity of a structural analogue, i.e. Fatty acids, C16-18, zinc salts, to Daphnia magna, the EC50 was also not reached up to a loading rate of 100 mg Fatty acids, C16-18, zinc salts/L at pH 6 and 8, 3 magnitudes above the respective water solubility. Thus, acute toxicity data froma zinc salt of a longer-chained fatty acid (C16 -18), support the conclusion that zinc salts of fatty acids with a similar structural analogy, water solubility and zinc content appear to not be toxic to invertebrates at concentrations below the respective water solubility limit

In sum, a derivation of a respective PNEC does not appear to be necessary. However, the PNEC water does not cover only short-term toxicity but also long-term toxicity. As aquatic long-term toxicity data are not available for zinc dilaurate, a read-across to insoluble/slightly soluble zinc substances is made, and the PNECs water as derived in the Chemical Safety Assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 are read-across to zinc dilaurate. For a comprehensive overview of the acute aquatic toxicity of (soluble) zinc to invertebrates, see the hazard assessment of soluble zinc within the framework of Regulation (EC) No 1907/2006 in Appendix 1 of the CSR and cited in excerpts below.

ZINC:

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.

Key data (lowest EC50 values) 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