Zinc bis[12-hydroxyoctadecanoate]

Short-term toxicity to aquatic invertebrates

Description of key information

Zinc bis[12-hydroxyoctadecanoate]:
Based on similar structural analogy, water solubility and zinc content of zinc bis[12-hydroxyoctadecanoate] (CAS 35674-68-1) and Fatty acids, C16-18, zinc salts (CAS 91051-01-3), a 1:1 read-across of ecotoxicological data of Fatty acids, C16-18, zinc salts is applied to zinc bis[12-hydroxyoctadecanoate].
The acute toxicity of the structural analogue (i. e. a similar fatty acid zinc salt: substance fatty acids, C16-18, zinc salts) to invertebrates is above the water solubility limit of around 1 mg/L. Therefore, the acute toxicity of zinc bis[12-hydroxyoctadecanoate] to invertebrates is also expected to be above the water solubility (ranging from < 0.01 - 1.69 mg/L). 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

Additional information

Zinc bis[12-hydroxyoctadecanoate]:

Based on similar structural analogy, water solubility and zinc content of zinc bis[12-hydroxyoctadecanoate] (CAS 35674-68-1) and Fatty acids, C16-18, zinc salts (CAS 91051-01-3), a 1:1 read-across of ecotoxicological data of Fatty acids, C16-18, zinc salts is applied to zinc bis[12-hydroxyoctadecanoate].

Acute toxicity of a structural analogue Fatty acids, C16-18, zinc salts to the waterflea Daphnia magna at pH 6 and 8 was not reached up to and including a loading rate of 100 mg Fatty acids, C16-18; zinc salts/L; the EC50 is > 100 mg/L. Since the structural analogue is not toxic to aquatic invertebrates up to and including its water solubility limit of around 1mg/L, zinc bis[12-hydroxyoctadecanoate] with a water solubility ranging from <0.01 to 1.69 mg/L is also not expected to be an acute hazard to aquatic invertebrates. This is supported by the results of a screening study on zinc bis[12-hydroxystearate] itself (Rudolf 2002) in which an EC50 was not reached at a nominal loading of 1000 mg/L (Rudolf 2002).

Furthermore, 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 also not reached up to 10 mg zinc dilaurate/L at pH 7.8. Thus, acute toxicity data from another structural analogue, i.e. zinc dilaurate - a zinc salt of a shorter-chained fatty acid (C12) and thus relatively higher zinc content, support the conclusion that zinc salts of fatty acids are not toxic to invertebrates. 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 bis[12-hydroxyoctadecanoate], 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 bis[12-hydroxyoctadecanoate]. For a comprehensive overview of the ecotoxicity of zinc, see the hazard assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 as follows:

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