2-ethylhexanoic acid, copper salt

Endpoint summary

Description of key information

Aquatic toxicity studies of 2-ethylhexanoic acid, copper salt are not available. Thus, read-across to the assessment entities soluble copper substances and 2-ethylhexanoic acidis applied since the ions of 2-ethylhexanoic acid, copper saltdetermine its fate and toxicity in the environment. Reliable studies indicate that the moiety of ecotoloxicological 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. 

 

2-ethylhexanoic acid

Acute data are available from studies for three trophic levels: algae, invertebrates and fish

- a 72-h ErC50 of 49.3 mg/L was identified for the algae Desmodesmus subspicatus (acc. To DIN 38412 part 9)

- a 48-h EC50 of 85.4 mg/L represents the lowest value identified for the invertebrate species Daphnia magna

- an unbounded value of > 100 mg/L (96-h LC50) was identified for the freshwater fish species Oryzias latipes based on data of an analogous substance (sodium 2-ethylhexanoate). Further studies of 2-ethylhexanoate with the freshwater fish species Oncorhynchus mykiss, Lepomis gibbosus and Leuciscus idus resulted in 96-h LC50 values > 100 mg/L

 

In sum, 2-ethylhexanoic acid has a low potential for acute aquatic toxicity.

 

Chronic data are available from studies for algae, aquatic invertebrates and microorganisms:

- a 72-h EC10 of 32.0 mg/L was identified for the green algae Desmodesmus subspicatus (acc. To DIN 38412 part 9)

- 21-d NOEC values of 18 mg/L and of 25.0 mg/L were identified for Daphnia magna.

- a 17-h EC10 of 71.7 mg/L was identified for the inhibition of bacterial growth (Pseudomonas putida)

 

In sum, 2-ethylhexanoic acid has a very low potential for chronic aquatic toxicity to algae and invertebrates and appears to be of low toxicity to microorganisms.

 

2-ethylhexanoic acid, copper salt

Based on acute and chronic ERVs of copper ions of 12.1 µg Cu/L (acute, pH 6) and 12 µg Cu/L (chronic, pH 7), and acute and chronic effect concentrations of 2 -ethylhexanoic acid being > 10 mg/L, the aquatic hazard assessment is based on copper ions as the toxic moiety of 2-ethylhexanoic acid, copper salt. Therefore, existing aquatic toxicity effect concentrations of copper are recalculated for 2-ethylhexanoic acid, copper salt based on the respective maximum copper content of 19% in 2-ethylhexanoic acid, copper salt resulting in:

Acute ERV (2-ethylhexanoic acid, copper salt): 63.68 µg/L, and

Chronic ERV (2-ethylhexanoic acid, copper salt): 63.16 µg/L.

 

The toxic potential of 2-ethylhexanoic acid, copper salt towards microorganisms is estimated with 1.21 mg/L based on a maximum copper content of 2-ethylhexanoic acid, copper salt of 19% and the 30-d NOEC of 0.23 mg dissolved Cu/L.