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Administrative data

additional ecotoxicological information
Type of information:
other: experimental studies were performed and compared to QSAR data
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation

Data source

Reference Type:
A review of the environmental fate and aquatic effects of a series of C4 and C8 oxo-process chemicals.
Staples, C.A.
Bibliographic source:
Chemosphere 45 (2001) 339—346

Materials and methods

Test guideline
equivalent or similar to guideline
Principles of method if other than guideline:
Test methods used with fish, invertebrates, algae, and microorganisms were generally based on acceptable standard methods developed by the US. EPA, other individual countries, or the OECD. Many of the tests were conducted in the 1970s and 1980s and employed less formal good laboratory practices than now commonly used; however, the early studies are generally confirmed by later studies that used more current methods.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
2-ethylhexanoic acid
EC Number:
EC Name:
2-ethylhexanoic acid
Cas Number:
Molecular formula:
2-ethylhexanoic acid
Test material form:

Results and discussion

Any other information on results incl. tables

Acute toxicity data:

Fish: For 2-ethylhexanoic acid, a range of 96h LC50 values from 70,000 to 270,000 µg/ was reported (SIDS, 1993). No chronic fish toxicity data are available for this compound.

Invertebrates: For D. magna, 24 -48h EC50 values were 26,000 to 205,000 ug/ for butyl acetate, 2-ethylhexanol, and 2-ethylhexanoic acid (SIDS, 1993).

Algae: For 2 -ethylhexanoic acid the freshwater green alga Scenedesmus quadricauta or S. subspicatus was used and the

threshold (EC10) was 25,000 µg/l (SIDS, 1993).

Microorganisms: The toxicity of 2-ethylhexanoic acid has been measured using the bacteria Pseudomonas putida in a threshold test of 16-18 h. Thresholds ranged from 110,000 µg/l to 2,250,000 µg/l (SIDS, 1993).

See also attached illustration (Fig 2).

ECOSAR calculations:

For 2-ethylhexanoic acid, ECOSAR multiplied the SAR-calculated values by 10 due to the acid moiety.

Calculated chronic toxicity values for fish and daphnids were 33,890 and 18,410 µg/l, respectively, for 2-ethylhexanoic acid.

As calculated acute fish toxicity results were within a factor of about 2 of measured acute data from flow-through tests, ECOSAR calculated chronic values

for fish and daphnids are assumed to be good estimates.

For 2-ethylhexanoic acid, a measured algal EC10 of 25,000 µg/l compares well with the calculated algal chronic value of 25,780 µg/l.

Applicant's summary and conclusion

The results that include both measured and calculated effects for a common species, demonstrate the utility of structure-activity relationships for enhancing the aquatic toxicity database.
Executive summary:

Environmental fate and aquatic effects data were examined for a series of C4 (butyl acetate, 1-butanol, isobutyl alcohol) and C8 (2-ethylhexanol and 2-ethylhexanoic acid) oxo-process chemicals. Manufacturing of these chemicals requires enclosed equipment, so environmental releases are generally limited to volatilization during their use, handling or transport. C4 compounds are more soluble and volatile, and would bind to soil and sediment to a lesser extent than C8 compounds. All five compounds were readily biodegradable based on OECD and APHA tests conducted up to 28 days. Atmospheric photo-oxidation half-lives range from 0.43 to 3.8 days. Toxicity data show that all five compounds pose generally low concern to fish, invertebrates, algae, and microorganisms. Overall, the data show that inadvertent releases of these compounds into the environment would be rapidly biodegraded in soil and water, volatilize to the atmosphere subject to photo-oxidation, while any residues remaining in water would pose a negligible threat to aquatic life.