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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Remarks:
Growth inhibition test with Pseudomonas putida
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Data for 2-aminoethanol (ethanolamine; CAS No. 141-43-5) and propionic acid (CAS No. 79-09-4) will be used to address the ecotoxicological data requirements for 2-ethyl-2-oxazoline (CAS No. 10431-98-8) in an analogue read-across approach. The basis for this read-across approach is that the test species are expected to rapidly transform the target substance into ethanolamine and propionic acid. The ecotoxicity of the ethanolamine transformation product will be assessed using information on ethanolamine, and the ecotoxicity of the propionic acid transformation product will be assessed using information on propionic acid.

2. SOURCE AND TARGET CHEMICAL(S)
The target substance is known to be of high purity (typically 99.5 % w/w), and to contain up to 1 % w/w (typically 0.5 % w/w) of its 2-methyl analogue as impurity. The impurity is expected to undergo the same transformation steps as the target substance, producing exactly the same ethanolamine transformation product but an analogous acetic acid transformation product in place of the propionic acid transformation product. On this basis, the source substances effectively represent typically >99.5 % w/w of the target substance. The purities of the samples of source substances that were tested are not specifically known, but it is assumed that they would not have been sufficiently impure as to substantially affect the study results. On this basis, the applicability of the data on the source substance to the target substance is not expected to be compromised by the presence of impurities in any of the substances.
See attached report for further details.

3. ANALOGUE APPROACH JUSTIFICATION
The basis for this read-across approach is that the target substance is expected to be rapidly transformed by the test species into ethanolamine and propionic acid according to the scheme presented in the attached report.
This transformation that is expected to occur in man is expected also to occur in the aquatic test species.
The ethanolamine transformation product is clearly identical to the first source substance, and the amount produced will be equivalent to 62% w/w of the loading of target substance.
The propionic acid transformation product is clearly identical to the second source substance, and the amount produced will be equivalent to 75% w/w of the loading of target substance.
The sum of the above values exceeds 100% due to the mass added by the incorporation of water of hydrolysis.
See attached report for further details.

4. DATA MATRIX
See attached report for further details.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across: supporting information
Specific details on test material used for the study:
The toxicity of 2-ethyl-2-oxazoline to sewage microorganisms (STP) is predicted based on the results of 2-aminoethanol and propionic acid.
Key result
Duration:
17 h
Dose descriptor:
EC10
Effect conc.:
60 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: Predicted value
Validity criteria fulfilled:
not applicable
Conclusions:
No test data to address the ecotoxicity of the target substance are available. On the basis of available data on the two source substances, sewage microorganisms are more sensitive to propionic acid than 2-aminoethanol. 2-aminoethanol appears to be less toxic to sewage microorganisms (STP) with a reported 3-hr IC50 of > 1,000 mg/L in an activated sludge respiration inhibition test (ASRIT). In contrast, a 17-hr EC10 of 45 mg/L has been reported for Pseudomonas putida when exposed to propionic acid. During metabolism the target substance produces 62% 2-aminoethanol and 75% propionic acid. As such, based on these values the target substance predicted aquatic toxicity values are: 3-hr IC50 (ASRIT) >1,613 mg/L based on 2-aminoethanol and 17-hr EC10 (P. putida) 60 mg/L based on propionic acid. For risk assessment the conservative 17-hr EC10 (P. putida) 60 mg/L will be applied, as this value derives the more protective PNEC (STP) value.

Description of key information

No test data to address the ecotoxicity of the target substance are available. On the basis of available data on the two source substances, sewage microorganisms are more sensitive to propionic acid than 2-aminoethanol.  2-aminoethanol appears to be less toxic to sewage microorganisms (STP) with a reported 3-hr NOEC of > 1,000 mg/L in an activated sludge respiration inhibition test (ASRIT). In contrast, a 17-hr EC10 of 45 mg/L has been reported for Pseudomonas putida when exposed to propionic acid. During metabolism the target substance produces 62% 2-aminoethanol and 75% propionic acid.  As such, based on these values the target substance predicted aquatic toxicity values are: 3-hr NOEC (ASRIT) >1,613 mg/L based on 2-aminoethanol and 17-hr EC10 (P. putida) 60 mg/L based on propionic acid.  For risk assessment the conservative 17-hr EC10 (P. putida) 60 mg/L will be applied, as this value derives the more protective PNEC (STP) value.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
60 mg/L

Additional information

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