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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
EU Method C.5 (Degradation: Biochemical Oxygen Demand)
Version / remarks:
Cited as Directive 92/69/EEC, C.5
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 A (Inherent Biodegradability: Modified SCAS Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
not specified
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 1.08 mg/L
Based on:
test mat.
Initial conc.:
ca. 2.06 mg/L
Based on:
test mat.
Initial conc.:
ca. 100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
DOC removal
Remarks:
Only as supplementary parameter in OECD 301C test at 100 mg/L after 28 d (end of test period).
Parameter followed for biodegradation estimation:
test mat. analysis
Remarks:
Only as supplementary parameter in OECD 301C test at 100 mg/L after 28 d (end of test period).
Details on study design:
No details reported.
Reference substance:
acetic acid, sodium salt
Reference substance:
other: mixture of glucose and glutamic acid
Parameter:
% degradation (O2 consumption)
Value:
ca. 86
Sampling time:
28 d
Remarks on result:
other: OECD 301C (MITI (I)) test, 100 mg/L test concentration
Parameter:
% degradation (DOC removal)
Value:
ca. 97
Sampling time:
28 d
Remarks on result:
other: OECD 301C (MITI (I)) test, 100 mg/L test concentration
Parameter:
% degradation (test mat. analysis)
Remarks:
Primary degradation product (2-ethylhexanol) was not detected.
Value:
ca. 100
Sampling time:
28 d
Remarks on result:
other: OECD 301C (MITI (I)) test, 100 mg/L test concentration
Parameter:
% degradation (DOC removal)
Value:
100
Sampling time:
24 h
Remarks on result:
other: SCAS test
Details on results:
The testing of ethylhexyl lactate in a ready biodegradability test according to OECD 301 C demonstrated a mean biodegradability of 86 % was found after 28 days (based on oxygen consumption). Based on the dissolved organic carbon (DOC) and the concentration of test substance remaining in the test medium, a biodegradability of 97% and 100% respectively could be confirmed. The hydrolysis product (ethylhexanol) could not be detected in the test medium.

Inherent biodegradability SCAS tests were also carried out with 2-ethylhexyl lactate. In this test, activated sludge (2 g (d.w.)/L) was fed daily with the test substance (about 40 mg/L). The test substances were shown to be completely removed within 24 hours by DOC determinations as well as by specific analysis of the effluents.
Parameter:
BOD5
Value:
ca. 0.47 g O2/g test mat.
Remarks on result:
other: 301 C
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
2-ethylhexyl-S-lactate is readily biodegradable.
Executive summary:

The biodegradation of lactic acid and lactate esters was studied. The aim of the study was to provide predicted environmental data for additional alkyl homologues and metal salts. Lactic acid and its alkyl esters were degraded for more than 60 % in the ready biodegradability tests. Specifically, 2-ethylhexyl lactate is readily biodegradable, with 86 % degradation (O2 consumption) after 28 days.

In an test according to the Inherent Biodegradability : Modified SCAS Test the substance was completely degraded after 24 h according to DOC.

Description of key information

2-Ethylhexyl lactate is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

Published data on the biodegradability of 2 -ethylhexyl lactate are availabe. The test was conducted according to OECD guideline 301 C. After 28 days 86 % degradation was achieved (based on oxygen consumption).