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Aquatic toxicity studies of fatty acids, C9-13-neo, copper salts are not available. Thus, read-across to the assessment entities soluble copper substances and neodecanoic acid (as a structural analogue of fatty acids, C9-13-neo) is applied since the ions of fatty acids, C9-13-neo, copper salts determine its fate and toxicity in the environment. Reliable aquatic toxicity studies indicate that the moiety of ecotoxicological concern are copper cations. 

 

Copper:

A large set of reliable aquatic toxicity data on copper ions is available from multiple studies covering all relevant trophic levels. The lowest acute and chronic Ecotoxicity Reference Values (ERVs) derived for copper at different pH bands amount to 12 µg Cu/L (acute, pH 6) and 12 µg Cu/L (chronic, pH 7). Please refer to the respective section of the assessment entity and to attached reports for further information on acute and chronic aquatic toxicity of copper:

"The environmental hazard classification of copper, Version 1.1 (European Copper Institute, 2018)"

"Derivation of acute ERVs for copper, (European Copper Institute, 2016)"

"Derivation of chronic Ecotoxicity Reference Values (ERVs) for copper, updated version (European Copper Institute, 2018)"

 

The potential of copper for toxicity to microorganisms is based on a weight-of-evidence approach of five studies, resulting in a 30-d NOEC of 0.23 mg dissolved Cu/L (inhibition of total respiration / respiration rate) for microorganisms. 

 

Neodecanoate (structural analogue of fatty acids, C9-13-neo anions):

Reliable acute data are available from GLP-conform guideline studies for three trophic levels: algae, invertebrates and fish

- an unbounded value of > 100 mg/L (96h-LL50) was identified for rainbow trout

- an unbounded value of > 457 mg/L (48h-EL50) was identified for the invertebrate species Daphnia magna

- an unbounded value of > 100 mg/L (72h-LL50) was identified for the algae Pseudokirchneriella subcapitata 

Reliable chronic data are available from GLP-conform guideline studies for two trophic levels: invertebrates and fish

- 21-d NOEC of 4.78 mg/L neoheptanoic acid (structural analogue) for reproduction of D. magna; Chronic Value (ChV) of 1.7 mg/L (QSAR-based estimate) for daphnids

- 14-d NOEC of 2.22 mg/L neodecanoic acid for growth of Oncorrhynchus mykiss; Chronic Value (ChV) of 1.6 mg/L (QSAR-based estimate) for fish

- Regarding algae, an EC10 or NOEC is not available for neodecanoate. However, based on the fact that the EC50 for growth rate of algae is > 100 mg/L, we may assume that it is unlikely that the EC10/NOEC < 1 mg/L. According to the QSAR-based outcome of the model ECOSAR v.2.0, neodecanoic acid has a very low potential for chronic toxicity to green algae since the chronic value (ChV = 10^([log (LOEC x NOEC)]/2)) of 12.3 mg/L is >> 1 mg/L.

Regarding the toxicity to aquatic microorganisms, a 4-h NOEC of ≥ 200 mg/L for the inhibition of nitrification by microorganisms (Nitrosomonas sp.) is available.

In sum, neodecanoic acid has very low potential for acute aquatic toxicity and a low potential for chronic toxicity.

Fatty acids, C9 -13-neo, copper salts:

Regarding the acute and chronic aquatic toxicity of neodecanoic acid (structural analogue of fatty acids, C9-13-neo), all acute LC/EC50 values and chronic NOEC/EC10 values are >>1 mg neodecanoic acid /L. Thus, taking into account acute and chronic ERVs of copper ions of 12.1 µg Cu/L (acute, pH 6) and 12 µg Cu/L (chronic, pH 7), respectively, the aquatic hazard assessment is based on copper ions as the most toxic moiety of fatty acids, C9-13-neo, copper salts. Therefore, existing ERVs of copper are recalculated for fatty acids, C9-13-neo, copper salts based on the maximum copper content of fatty acids, C9-13-neo, copper salts of 16.6 % resulting in :

- an acute ERV (fatty acids, C9-13-neo, copper salts) of 72.9 µg/L, and a

- chronic ERV (fatty acids, C9-13-neo, copper salts) of 72.3 µg/L.

The toxic potential of fatty acids, C9-13-neo, copper salts to microorganisms is estimated with 1.39 mg/L based on a maximum copper content of fatty acids, C9-13-neo, copper salts of 16.6 % and the 30-d NOEC of 0.23 mg dissolved Cu/L

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