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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: screening tests
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Principles of method if other than guideline:
Method: The study was conducted according to the French AFNOR T 90-302 test guideline(1977).
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: aerobic microorganisms
Duration of test (contact time):
42 d
Initial conc.:
40 mg/L
Based on:
DOC
Parameter:
not specified
Value:
0 - 10
Sampling time:
42 d
Interpretation of results:
under test conditions no biodegradation observed
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Principles of method if other than guideline:
Method: The carbon dioxide evolution test was conducted according to Sturm (1973). Sturm RN (1973). J. Amer. Oil Chem. Soc. 50: 159-167
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: sewage treatment plant effluent, adapted
Duration of test (contact time):
42 d
Initial conc.:
10 mg/L
Based on:
DOC
Parameter:
% degradation (CO2 evolution)
Value:
10
Sampling time:
28 d
Details on results:
RS-Freetext:
CO2 evolution: 10 %
DOC removal: 22 %
Interpretation of results:
other: Under the conditions of the test, the test substance was poorly biodegradable.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Principles of method if other than guideline:
The closed bottle test was conducted according to Fischer et al. (1974). Fischer WK, Gerike P, Schmid R (1974). Z. Wasser Abwasser Forsch. 7: 99-118
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
Inoculum: 1 drop of effluent/L
Duration of test (contact time):
30 d
Initial conc.:
1 mg/L
Based on:
DOC
Parameter:
% degradation (O2 consumption)
Value:
0 - 10
Sampling time:
30 d
Interpretation of results:
under test conditions no biodegradation observed
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Principles of method if other than guideline:
Method: The OECD Screening test was conducted according to a method described by  the Umweltbundesamt (1978) and The OECD (1976).
Umweltbundesamt (1978). OECD Chemicals Testing Programm. Expert Group C  "Persistence", Draft Working Papers, 31 Mar 1978 OECD Environment Directorate (1976). Proposed Method for the  Determination of the Biodegradability of Surfactants used in Synthetic  Detergents,
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Duration of test (contact time):
19 d
Initial conc.:
3 - 20 mg/L
Based on:
DOC
Parameter:
% degradation (DOC removal)
Value:
10
Sampling time:
19 d
Interpretation of results:
other: Under the conditions of the test, the test substance was poorly biodegradable.
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Principles of method if other than guideline:
Method: Zahn-Wellens test conducted according to the method described by Zahn and Wellens (1974). Zahn R, Wellens H (1974). Chemiker Z. 98: 228-232
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial (adaptation not specified)
Duration of test (contact time):
14 d
Initial conc.:
400 mg/L
Based on:
DOC
Parameter:
% degradation (DOC removal)
Value:
30 - 40
Sampling time:
14 d
Interpretation of results:
other: Under the conditions of the test, the test substance was partly eliminated from water.
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 A (Inherent Biodegradability: Modified SCAS Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Duration of test (contact time):
100 d
Initial conc.:
65 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Parameter:
% degradation (DOC removal)
Value:
90 - 100
Sampling time:
28 d

It could be shown in three different experiments that a change of the  pH-value can result in a biodegradation of EDTA.
 
In a SCAS facility which had been inoculated with activated sludge from a  municipal wastewater treatment plant, a removal by biodegradation of EDTA  (65 mg/L) added to domestic wastewater could be observed at pH of 8.0 to  9.0. With a pH of 6.5 no biodegradation could be obtained. The removal at  pH 8.5 started 3 weeks after inoculation with a result up to 100 %  degradation after 28 days. The SCAS unit ran with sludge retention times  > 12 days. A maximum EDTA removal rate of 0.2 kg/m3/day was achieved.

In order to confirm the biodegradation of EDTA, closed bottle tests were  carried out with sludge originating from the SCAS unit. The tests were  conducted at a pH range from 8.0 to 8.5. The lag period was only few  days. The time to reach a BOD/ThOD ratio of 0.6 was 3 weeks after  initiation of detectable biodegradation. EDTA was not biodegraded at pH  7.0.

The removal of EDTA was investigated in a full-scale activated sludge  plant operated at pH values between 7.5 and 8.5 with dairy wastewater  containing ca. 30 mg/l EDTA. The dairy wastewater was treated at a  hydraulic residence time of one day and a sludge retention time of 20  days. The analysis of influent, effluent and sludge concentration resulted in  approximately 90 % removal. At a pH of 6.7 no biodegradation took place.

Interpretation of results:
other: ultimately biodegradable
Endpoint:
biodegradation in water: screening tests
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material. An analogue justification is attached in section 13 of dataset.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)
Principles of method if other than guideline:
Biodegradability tests were performed using a combined CO2/DOC method that allows the simultaneous determination of CO2 formation and of DOC removal according to the updated ISO 9439, 1998.
Additional a monitoring study conducted at a industrial wastewater treatment plant dedicated to treat the effluent from a paper mill. The monitoring measurements on the influent and the treated effluent showed an EDTA elimination of about 80 % by test substance specific analysis.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial, adapted
Details on inoculum:
Activated sludge taken from a Finnish industrial wastewater treatment plant.
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
Monitoring study (waste water treatment plant): 50 separate samples of influent and treated effluent were taken daily over a period of two weeks.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
80 - 90
Sampling time:
28 d
Key result
Parameter:
% degradation (DOC removal)
Value:
90 - 100
Sampling time:
28 d
Details on results:
In the present publication, it was shown that EDTA is ultimately biodegraded under practical industrial wastewater treatment conditions, involving a Finnish plant dedicated to treat the effluent from a paper mill. Monitoring measurements on the influent and the treated effluent showed an EDTA elimination of about 80 % by test substance specific analysis. The mean EDTA concentration in the influent was 23.8 mg/L and in the corresponding effluent 5.8 mg/L. The biodegradability of EDTA was verified in the laboratory with activated sludge from the treatment plant. Using a combined CO2/DOC method the total mineralization of EDTA was indicated by > 80 % CO2 formation and >= 99 % DOC removal
Interpretation of results:
other: ultimately biodegradable
Endpoint:
biodegradation in water: screening tests
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Principles of method if other than guideline:
Method: Cells of the mixed culture were employed in a fluidized bed reactor with sand as support material.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial, adapted
Details on inoculum:
EDTA-degrading bacterial mixed culture from industrial sewage receiving EDTA-containing wastewater effluents and two isolated bacteria strains (BNC1 and BNC2) were used as inoculum. obtained from industrial sewage receiving EDTA-containing waste water effluents. A special enrichment procedure was applied.
Initial conc.:
292 mg/L
Based on:
test mat.
Parameter:
% degradation (test mat. analysis)
Value:
ca. 90 - ca. 100
Sampling time:
10 d

The bacterial mixed culture which was obtained from sewage by a special  enrichment procedure, utilized EDTA as the sole source of carbon and  nitrogen for growth. The chemical speciation did not influence the  biodegradability of EDTA.

A gram-negative isolate from the mixed population (BNC1) also metabolized  EDTA in monoculture. Growth of the pure culture was slow compared to the  original community and always accompanied by the accumulation of  unidentified metabolites. In contrast, a two species culture of strain BNC1 and a gram-positive isolate (BNC2) grew resembling the original mixed community without noticeable accumulation of metabolites.

Interpretation of results:
other: The test compound was biodegradable after acclimation under the conditions of this study.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions (signature of the study director missing)
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Deviations:
yes
Remarks:
Water from the river Rhine was used as inoculum
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: fresh water from the river Rhine
Details on inoculum:
Water from the river Rhine was used as inoculum which had been taken upstream from the spot where the effluent of waste water treatment plant was discharged into the river.
Duration of test (contact time):
60 d
Initial conc.:
20 mg/L
Based on:
DOC
Initial conc.:
62 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The pH of the test medium was adjusted to 6.5 at test start and during the course of the study controlled and if necessary readjusted.
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
0 - 10
Sampling time:
60 d
Interpretation of results:
under test conditions no biodegradation observed
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study (signature of the study director missing)
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Deviations:
yes
Remarks:
Water from the river Rhine was used as inoculum
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: fresh water from the river Rhine
Details on inoculum:
Water from the river Rhine was used as inoculum which had been taken upstream from the spot where the effluent of waste water treatment plant was discharged into the river.
Duration of test (contact time):
60 d
Initial conc.:
20 mg/L
Based on:
DOC
Initial conc.:
62 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The pH of the test medium was adjusted to 8.5 at test start and during the course of the study controlled and if necessary readjusted.
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
70 - 80
Sampling time:
60 d
Details on results:
Kinetic of test substance (in %):
= 0 after 28 day(s)
= 5 after 32 day(s)
= 22 after 35 day(s)
= 52 after 46 day(s)
= 73 after 60 day(s)
Interpretation of results:
other: biodegradable after adaptation
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study (signature of the study director missing)
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
The inoculum was activated sludge, adapted to the test substance, taken from a previous biodegradation study (Project No. 99/0668/21/2).
Duration of test (contact time):
28 d
Initial conc.:
61.9 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
aniline
Parameter:
% degradation (CO2 evolution)
Value:
0 - 10
Sampling time:
28 d
Interpretation of results:
other: poorly biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study (signature of the study director missing)
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Deviations:
yes
Remarks:
Water from the river Rhine was used as inoculum
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: fresh water from the river Rhine
Details on inoculum:
Water from the river Rhine was used as inoculum which had been taken downstream from the spot where the effluent of waste water treatment plant was discharged into the river.
Duration of test (contact time):
60 d
Initial conc.:
20 mg/L
Based on:
DOC
Initial conc.:
62 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The pH of the test medium was adjusted to 6.5 at test start and during the course of the study controlled and if necessary readjusted.
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
0 - 10
Sampling time:
60 d
Interpretation of results:
under test conditions no biodegradation observed
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study (signature of the study director missing)
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
The inoculum was activated sludge adapted to the test substance taken from a previous biodegradation study (Project No. 99/0668/21/4).
Duration of test (contact time):
28 d
Initial conc.:
61.9 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
aniline
Parameter:
% degradation (CO2 evolution)
Value:
0 - 10
Sampling time:
28 d
Interpretation of results:
other: poorly biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study (signature of the study director missing)
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Deviations:
yes
Remarks:
Water from the river Rhine was used as inoculum
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: fresh water from the river Rhine
Details on inoculum:
Water from the river Rhine was used as inoculum which had been taken downstream from the spot where the effluent of waste water treatment plant was discharged into the river.
Duration of test (contact time):
60 d
Initial conc.:
20 mg/L
Based on:
DOC
Initial conc.:
62 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The pH of the test medium was adjusted to 8.5 at test start and during the course of the study controlled and if necessary readjusted.
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
90
Sampling time:
60 d
Details on results:
Kinetic of test substance (in %):
= 0 after 28 day(s)
= 16 after 40 day(s)
= 57 after 49 day(s)
= 76 after 54 day(s)
= 89 after 60 day(s)
Interpretation of results:
other: biodegradable after adaptation
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial (adaptation not specified)
Details on inoculum:
The activated sludge inoculum used in this study originated from an industrial wastewater treatment plant (BASF AG). The concentration of dry substance was 1 g/L.
Duration of test (contact time):
28 d
Initial conc.:
400 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Parameter:
% degradation (DOC removal)
Value:
0 - 10
Sampling time:
28 d
Details on results:
Kinetic of test substance (in %):
= 0 after 3 hour(s)
= 0 after 7 day(s)
= 5 after 11 day(s)
= 8 after 28 day(s)
Interpretation of results:
other: poorly eliminated from water
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: fresh water from the river Rhine
Duration of test (contact time):
72 d
Initial conc.:
40 mg/L
Based on:
DOC
Initial conc.:
140 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The test substance was added directly to the inoculum without addition of mineral test medium.
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (DOC removal)
Value:
0 - 10
Sampling time:
28 d
Parameter:
% degradation (DOC removal)
Value:
90 - 100
Sampling time:
72 d
Details on results:
Test duration (days) : 72

pH: 7 - 7.5
Degradation degree of the test substance at the end of the test (% DOC): < 10

pH: 8
Duration of adaptation phase (days): 28 (mean)
Duration of the biodegradation phase (days): 20
Degradation degree of the test substance at the end of the 10-day window (% DOC): 0
Degradation degree of the test substance at the end of the test (% DOC): 80 - 90

pH: 8.5
Duration of adaptation phase (days): 28 (mean)
Duration of the biodegradation phase (days): 30
Degradation degree of the test substance at the end of the 10-day window (% DOC): 0
Degradation degree of the test substance at the end of the test (% DOC): 90 - 100


Biodegradation degree (DOC removal) after 28 days: < l0%
Biodegradation degree (DOC removal) after 72 days: 90 -100%


Inhibition control (sodium benzoate):
Inhibition control (DOC removal) after 14 days (pH 7.0): 40 - 50%
Interpretation of results:
other: The test substance is in this test biodegradable after adaptation at pH 8.0-8.5.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: fresh water from the river Rhine
Details on inoculum:
Rhine-water from the gauging station in Bad Honeff. Concentration of dry substance was not measured.
Duration of test (contact time):
70 d
Initial conc.:
20 mg/L
Based on:
DOC
Initial conc.:
104 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (DOC removal)
Value:
0 - 10
Sampling time:
28 d
Parameter:
% degradation (DOC removal)
Value:
80 - 90
Sampling time:
59 d
Details on results:
Test duration (days): 70
Duration of the adaptation phase (days): 50
Duration of the degradation phase (days): 10

Degradation of the test substance at the end of the 10-day window (% DOC): 0

Degradation degree of the test substance after 59 days at the end of test 1 (% DOC): 80-90
Degradation degree of the test substance after 70 days at the end of test 2 (% DOC): 80-90

Biodegradation degree (DOC removal) after 28 days: 0-10 %
Biodegradation degree (DOC removal) after 59 days: 80-90 %

Kinetic of test substance (in %):
= 0 after 28 day(s)
= 4 after 49 day(s)
= 86 after 57 day(s)
Kinetic of control substance (in %):
= 90 ... 100 after 14 day(s)
Interpretation of results:
other: The test substance was biodegradable after adaptation, but not readily biodegradable according to OECD criteria
Endpoint:
biodegradation in water: screening tests
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: fresh water from the river Rhine
Details on inoculum:
Mixture from fresh Rhinewater and adapted Rhinewater from Scas-Test.
Duration of test (contact time):
44 d
Initial conc.:
20 mg/L
Based on:
DOC
Initial conc.:
72 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Parameter followed for biodegradation estimation:
DOC removal
Parameter:
% degradation (CO2 evolution)
Value:
30 - 40
Sampling time:
28 d
Parameter:
% degradation (DOC removal)
Value:
90 - 100
Sampling time:
28 d
Details on results:
Test duration (days): 44
Duration of the adaptation phase (days): 16
Duration of the degradation phase (days): 28

Biodegradation degree (C02/ThCO2) after 28 days: 30-40 % (14 %, 27 %, 55 %)
Elimination degree (DOC) after 28 days: 90-100 % (76 %, 100 %, 101 %)

The deviation of the degradation degree of the test substance in the plateau phase (> 20 %) was justified in the high pH value from > 9.0 and the difference in the test-vessels. So CO2 was solved as (CO3)2- and not stripped and measured in the absorption-vessels.

The test substance is in this test moderately or partially biodegradable.
But the test substance is in this test well eliminable from water.
Interpretation of results:
other: moderately or partially biodegradable and well eliminable from water
Endpoint:
biodegradation in water: screening tests
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Reliable Data taken from EU Risk Assessment
Justification for type of information:
Read across is based on a structurally similar material.
Reason / purpose for cross-reference:
assessment report
Principles of method if other than guideline:
Method: Environmental samples from a river, a ditch and a lake were examined in the closed bottle test.
GLP compliance:
no
Oxygen conditions:
aerobic
Key result
Parameter:
% degradation (DOC removal)
Value:
53 - 72
Sampling time:
28 d
Remarks on result:
other: pH8

Recent data suggest that under alkaline conditions EDTA can be degraded.

Environmental samples from a river, a ditch and a lake were examined in  the closed bottle test for their potential to degrade CaNa2EDTA in a concentration of 8.0 mg/l at pH 6.5 and 8.0 over a period of few weeks. The results show for all environmental samples that at pH 6.5 no or little biodegradation (2-12 %) occurred within the first 28 days. After 49 days a biodegradation between 60 and  83 % was obtained. At pH 8, rates of 53, 62 and 72 % were obtained after 28 days and 75-89 % after 35 days (Van Ginkel, 1999).

Different investigations show, that it is possible to obtain enrichment  cultures of EDTA-utilising microorganisms. So far three strains of  bacteria have been isolated breaking down EDTA completely. One of them could be identified as Agrobacterium sp. Counter-ions exert effects on  the biodegradation of chelating agents. The different results show, that metal-EDTA complexes with a thermodynamic stability constant below 1012,  like Ca, Mg and Mn, were degraded. Chelates with stability constants above 1012, such as Cu and Fe, were not degraded (Van Ginkel, 1999).

Results obtained at a pH of 8 could be relevant because the pH value of  lake and river water ranges from 7.7 to 8.5. However, in surface waters  EDTA is preferably complexed with heavy metal ions. Regarding the  degradation tests cited above, no biological degradation is expected. Ca-EDTA can only occur in the environment where strong point
sources release this species into a river with a low flow.

Description of key information

EDTA is not readily biodegradable according to OECD criteria, but ultimately biodegradable under special environmental conditions. It is expected that K2EDTA will dissociate and have the same biodegradation potential as EDTA.

Key value for chemical safety assessment

Additional information

A large number of degradation tests are available for EDTA (acid form) and its salt, for justification for read-across see IUCLID 5, Chapter 13. In most cases the acid or the Na salts were used as test substances. Results from OECD guideline tests indicate that EDTA is not readily biodegradable [e.g. Gerike & Fischer, 1979 and BASF AG, 1999, 2000, 2001, 2002]. Furthermore different tests on inherent biodegradability result in low biodegradation rates [e.g. BASF AG, 1987].

pH influences

It could be shown that a change of the pH-value have a great impact on the biodegradability of EDTA. In a SCAS test (OECD 302 A) biodegradation of EDTA could be observed at pH 8-9, but not at pH 6.5 [Van Ginkel & al., 1997]. Similar results obtained in a DOC removal test according to the principles of the OECD guideline 301 using natural surface water from the river Rhine as inoculum. After 60 days up to 100 % EDTA was degraded at pH 8.5 but less than 10 % at pH 6.5 [BASF AG, 2000]. These slightly alkaline conditions are realistic in environmental surface water compartments.

Adaptation

An enhanced biodegradability of EDTA could be shown after long adaption. In guideline tests according to OECD 301 EDTA was moderately biodegradable and well eliminable from water using adapted inoculum [BASF AG, 2001, 2002]. The adaptation potential of EDTA degradation shows also an industrial wastewater treatment plant from a Finnish paper mill. Using activated sludge from this plant EDTA was biodegraded about > 80 % CO2 evolution and about 99 % DOC removal in a laboratory study (OECD 301B) [Kaluza & al. 1998]. This study represents a low-level preadaption test system and can be regarded as an enhanced biodegradation screening test [Guidance for Implementation of REACH, Chapter R.7b, 2008]

Influences of the stability constant

As a chelating agent EDTA forms complexes with a lot of cationic ions. Fundamental EDTA exists naturally as a mixture of chelate complexes. The biodegradability differs between the acid resp. their salts and on the other side the metal complexes. Investigations show, that EDTA complexes with a thermodynamic stability constant below 10E12, like Ca, Mg and Mn, were degraded. Complexes with higher stability constants like Pb, Zn and Co are slowly degraded via the weaker complexes present in equilibrium. The degradation of complexes containing very bacteriotoxic metals like Cu or Cd stops as soon as sufficient metal is liberated [Klüner & al. 1998 and Van Ginkel, 1999, Nörtemann 2003, Satroudinov 2000, 2003].

Degradation pathway

Several investigations revealed that it is possible to enrich cultures of EDTA-utilizing microorganisms. Different bacteria strains were isolated which can mineralised EDTA completely [Nörtemann, 1992 and Van Ginkel, 1999]. The degradation pathway of EDTA was described from Klüner & al. (1998) and summarised in the EU Risk Assessment (2004). The first intermediate described is ethylenediaminetriacetate (ED3A). ED3A can react spontaneously to ketopiperazinediacetate (KPDA) by intramolecular cyclisation [Ternes et al., 1996]. KPDA itself is biodegradable which could be shown by Van Ginkel & Stroo (1999).

Conclusion

EDTA is not readily biodegradable according to OECD criteria. It was shown that under special conditions like slightly alkaline pH or adaptation the biodegradability of EDTA is considerably improved. EDTA was biodegradable in an enhanced test using preadapted activated sludge. Therefore it can be concluded that EDTA is ultimately biodegradable under such conditions.