2-ethylhexanoic acid

Endpoint summary

Description of key information

With high probability acutely not harmful for aquatic organisms.

Long-term effects are not expected.

Additional information

The substance 2-ethylhexanoic acid (CAS 149-57-5) leads to a decrease of the pH in the test solutions. Depending on the test item concentrations, the pH falls outside of the acceptable pH range for the test organisms; therefore, the test solutions should be pH-adjusted or, as an alternative, the salt of the acid can be used as a test item. In case of 2-ethylhexanoic acid, the sodium salt of the acid (CAS 19766-89-3) was used as test item as it resembles the acid without the pH effect on the test solutions.

For the risk assessment, the effect data based on test solutions outside the acceptable pH range should not be used since the quantities of the substance that would be found in natural waters are not likely to affect the pH to a relevant extent. It is likely that the L(E)C-values from the tests without neutralization overestimate the potential toxicity of these matrices. Therefore, the experimental data from the salt of the acid (sodium 2-ethylhexanoate, CAS 19766-89-3) which resembles the acid after neutralization was used for the assessment.

Short-term toxicity to fish: With high probability acutely not harmful to fish.

Key study: test item: Na salt of 2-ethylhexanoic acid (sodium 2-ethylhexanoate, CAS 19766-89-3):

NITE, J-CHECK (2002, report no. A010465-4). OECD 203, limit test, Oryzias latipes: 96-h LC50 > 100 mg/L (nom., analytically verified)

 

Long-term toxicity data to fish: Long-term effects are not to be expected.

Key study: test item: 2-ethylhexanoic acid (CAS 149-57-5):

ECOSAR v2.2, neutral organics: 30-d ChV = 29.7 mg/L

 

Short term toxicity to aquatic invertebrates: With high probability acutely not harmful to aquatic invertebrates.

Key study: Na salt of 2-ethylhexanoic acid (sodium 2-ethylhexanoate, CAS 19766-89-3):

NITE, J-CHECK (2002, report no. A010465-2). OECD 202, Daphnia magna:

48-h EC50 = 913 mg/L (nom., analytically verified)

 

Long-term toxicity to aquatic invertebrates:

Key study: Na salt of 2-ethylhexanoic acid (sodium 2-ethylhexanoate, CAS 19766-89-3):

NITE, J-CHECK (2002, report no. A010465-3). OECD 211, Daphnia magna:

21-d EC10 = 19.9 mg/L (nominal, analytically verified, re-calculated)

 

Supp. Study: 2-ethylhexanoic acid (CAS 149-57-5):

EKO LAB/Finnish Chemicals (1997, report no.: E2702), OECD 211, Daphnia magna:

21-d NOEC = 25 mg/L (nominal)

 

 

Toxicity to aquatic algae and cyanobacteria: With high probability acutely not harmful to algae.

Key study: Na salt of 2-ethylhexanoic acid (sodium 2-ethylhexanoate, CAS 19766-89-3):

NITE, J-CHECK (2002, report no. A010465-1). OECD 201, Pseudokirchneriella subcapitata:

72-h ErC50 = 485.1 mg/L (nominal, analytically verified, re-calculated)

72-h ErC10 = 231.2 mg/L (nominal, analytically verified, re-calculated)

 

Supp. Study: 2-ethylhexanoic acid (CAS 149-57-5):

BASF AG (1988, rep. no.: 2/0949/88), DIN 38412-9, Desmodesmus subspicatus

72 -h ErC50 > 500 mg/L (nominal, pH-adjusted)

72-h ErC50 = 49.3 mg/L (nominal, not pH-adjusted)

72-h ErC10 = 32 mg/L (nominal, not pH-adjusted)

The observed mortality is most likely due to the pH shift in the test solutions caused by the substance, but not due to an inherent toxic effect of the substance.

 

Toxicity to aquatic microorganisms: The inhibition of the degradation activity of activated sludge is not anticipated when introduced in appropriately low concentrations.

Key study: 2-ethylhexanoic acid (CAS 149-57-5):

BASF AG (1988, DIN 38412-8) Pseudomonas putida:

17-h EC10 = 71.7 mg/L, 17-h EC50 = 112.1 mg/L (nominal, not pH-adjusted)

 

Conclusion: Based on the available experimental data for the substance itself and its salt, 2-ethylhexanoic acid (CAS 149-57-5) is with high probability acutely not harmful to aquatic organisms. Long-term effects are not expected.