Reaction mass of potassium;sodium;2-[bis[2-[bis(carboxymethyl)amino]ethyl]amino]acetate;copper and potassium;sodium;2-[2-[bis(carboxymethyl)amino]ethyl-(2-hydroxyethyl)amino]acetate;copper

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

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:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 A (Inherent Biodegradability: Modified SCAS Test)

Qualifier:

according to guideline

Guideline:

ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)

Qualifier:

according to guideline

Guideline:

other: EN 29888

GLP compliance:

not specified

Specific details on test material used for the study:

analytical grade and purchased from Merck and Fluka.

Inoculum or test system:

other: activated sludge with adaptation time either 5 or 30 days

Details on inoculum:

Activated sludge suspended solids 200 mg/l, non-adapted and adapted under different mean biomass retention time sludge age) in days was the inoculum. The adaptation procedure was described previously Pitter and S ykora, 1996). Test parameter was % removal of DOC Dt ) and the test period was at least 28 d.
Experiments were carried out with non-adapted activated sludge and also with adapted activated sludge at sludge age within 5 d corresponding to usual wastewater treatment plants) and 30 d corre- sponding to aerobic sludge stabilization process).

Duration of test (contact time):

28 d

Initial conc.:

50 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

The organic compound was the sole source of organic carbon and energy for microorganisms.
It must be remembered that the concentration of complexing agents that can be complexed by metals is limited by stoichiometric considerations. Usually 1 mol EDTA and related compounds can complex a maximum of 1 mol of the metal. Inorganic composition of the bi- ological medium used was: Ca 0.25 mmol/l, Mg 0.1 mmol/l and Fe III) 0.001 mmol/l. Initial concentration of test substances approximately corresponds to 100 mg/ l, 0,34 mmol/l, respectively. This means that the for- mation of very stable Fe III) complex may be neglected.

Reference substance:

benzoic acid, sodium salt

Remarks:

sodium benzoate

Parameter:

% degradation (DOC removal)

Value:

>= 0 - <= 15

Sampling time:

28 d

Details on results:

All the above-mentioned chelating agents EDTA, DTPA, HEDTA, PDTA) with two or three tertiary ni- trogen atoms and hydroxyethyl or carboxymethyl groups in the molecule were stable under experimental conditions. DOC removal varied within 0% and 15%. The infl̄uence of the sludge age up to 30 d was not observed.

Tetrasubstituted derivatives with two tertiary nitrogen atoms and carboxymethyl- or 2-hydroxyethylgroups in the molecule (typical complexing agents EDTA, DTPA, PDTA, HEDTA) are biologically stable.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The biological degradability (Zahn-Wellens test, OECD 302A) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Tetrasubstituted derivatives with two tertiary nitrogen atoms and carboxymethyl- or 2-hydroxyethylgroups in the molecule typical complexing agents EDTA, DTPA, PDTA, HEDTA) are biologically stable.

Executive summary:

The biological degradability (Zahn-Wellens test) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Mixed bacterial culture (activated sludge) was used as inoculum (non-adapted sludge and sludge adapted at different mean biomass retention time, the so-called sludge age). Biodegradability of ethylene(propylene)di(tri)amine-based complexing agents depends on the character and number of substituents and nitrogen atoms in the molecule. Tetra penta)substituted derivatives with two or more tertiary nitrogen atoms and carboxymethyl or 2-hydroxyethyl groups in the molecule EDTA, DTPA, PDTA, HEDTA) are very stable from an environmental point of view

Reference 2

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:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)

GLP compliance:

not specified

Specific details on test material used for the study:

analytical grade and purchased from Merck and Fluka.

Inoculum or test system:

other: activated sludge with adaptation time either 5 or 30 days

Details on inoculum:

The inoculum was either non-adapted activated sludge collected at the municipal water treatment plant in Prague or an activated sludge adapted at different sludge age in the range of 5–30 days, which corresponds to the relations in medium- to low-load biological water treatment plants

Initial conc.:

50 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Two methods were combined for evaluating the complete biodegradability: the method of assaying dissolved organic carbon (EN ISO 7827) suitable for assessing ready biodegradability (X0 1⁄4 30 mg l-1, S01⁄4 DOC 50 mg l-1) and the Zahn-Wellens Test (EN ISO 9888) for assessing potential biodegradability (X0 1⁄4 30 mg l-1, S01⁄4 DOC 50 mg l-1).

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (DOC removal)

Value:

< 20

Sampling time:

28 d

Details on results:

All complexing agents based on tetra(penta)sub- stituted ethylenedi(tri)amine or propylenediamine with –CH2COOH substituents (EDTA, DTPA, HEDTA) were biologically stable even after a prolonged adaptation of the activated sludge up to age 30 days.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The susceptibility of ethylenediamine derivatives to biodegradation depends on the character and num- ber of nitrogen atoms and substituents in the molecule. The most stable are complexing agents containing in the molecule two and more tertiary nitrogen atoms and four or more carboxymethyl groups as substituents (e.g. EDTA, DTPA, HEDTA, PDTA). In terms of biological water treatment and spontaneous self- purification in surface water, these compounds belong among poorly biodegradable substances.

Executive summary:

Biological degradability of ethylenediamine derivatives depends on the type and number of substituents. The susceptibility to biodegradation decreases in the sequence of substituents –COCH3, –CH3, –C2H5, –CH2CH2OH, –CH2COOH and with polysubstitution. The biodegradability depends also on the kind and number of nitrogen atoms. Complexing agents with a single-nitrogen atom in the molecule (e.g. NTA) succumb relatively readily to biodegradation whereas, compounds with two or more tertiary amino groups are biologically highly stable and do not undergo biodegradation even in experiments with activated sludge adapted at an age of up to 30 days (EDTA, DTPA, PDTA, HEDTA). A lowering of the degree of substitution brings about an increased susceptibility to biodegradation. This holds, e.g., for replacement of tertiary amino groups with secondary ones; thus the symmetrically disubstituted ethylenediamine-N,N0-diacetic acid (EDDA) possesses still sufficient complexing ability while belong- ing already to the group of potentially degradable substances.

Reference 3

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:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 A (Inherent Biodegradability: Modified SCAS Test)

Qualifier:

according to guideline

Guideline:

ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)

Qualifier:

according to guideline

Guideline:

other: EN 29888

GLP compliance:

not specified

Specific details on test material used for the study:

analytical grade and purchased from Merck and Fluka.

Inoculum or test system:

other: activated sludge with adaptation time either 5 or 30 days

Details on inoculum:

Activated sludge suspended solids 200 mg/l, non-adapted and adapted under different mean biomass retention time sludge age) in days was the inoculum. The adaptation procedure was described previously Pitter and S ykora, 1996). Test parameter was % removal of DOC Dt ) and the test period was at least 28 d.
Experiments were carried out with non-adapted activated sludge and also with adapted activated sludge at sludge age within 5 d corresponding to usual wastewater treatment plants) and 30 d corre- sponding to aerobic sludge stabilization process).

Duration of test (contact time):

28 d

Initial conc.:

50 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

The organic compound was the sole source of organic carbon and energy for microorganisms.
It must be remembered that the concentration of complexing agents that can be complexed by metals is limited by stoichiometric considerations. Usually 1 mol EDTA and related compounds can complex a maximum of 1 mol of the metal. Inorganic composition of the bi- ological medium used was: Ca 0.25 mmol/l, Mg 0.1 mmol/l and Fe III) 0.001 mmol/l. Initial concentration of test substances approximately corresponds to 100 mg/ l, 0,34 mmol/l, respectively. This means that the for- mation of very stable Fe III) complex may be neglected.

Reference substance:

benzoic acid, sodium salt

Remarks:

sodium benzoate

Parameter:

% degradation (DOC removal)

Value:

>= 0 - <= 15

Sampling time:

28 d

Details on results:

All the above-mentioned chelating agents EDTA, DTPA, HEDTA, PDTA) with two or three tertiary ni- trogen atoms and hydroxyethyl or carboxymethyl groups in the molecule were stable under experimental conditions. DOC removal varied within 0% and 15%. The infl̄uence of the sludge age up to 30 d was not observed.

Tetrasubstituted derivatives with two tertiary nitrogen atoms and carboxymethyl- or 2-hydroxyethylgroups in the molecule (typical complexing agents EDTA, DTPA, PDTA, HEDTA) are biologically stable.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The biological degradability (Zahn-Wellens test, OECD 302A) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Tetrasubstituted derivatives with two tertiary nitrogen atoms and carboxymethyl- or 2-hydroxyethylgroups in the molecule typical complexing agents EDTA, DTPA, PDTA, HEDTA) are biologically stable.

Executive summary:

The biological degradability (Zahn-Wellens test) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Mixed bacterial culture (activated sludge) was used as inoculum (non-adapted sludge and sludge adapted at different mean biomass retention time, the so-called sludge age). Biodegradability of ethylene(propylene)di(tri)amine-based complexing agents depends on the character and number of substituents and nitrogen atoms in the molecule. Tetra penta)substituted derivatives with two or more tertiary nitrogen atoms and carboxymethyl or 2-hydroxyethyl groups in the molecule EDTA, DTPA, PDTA, HEDTA) are very stable from an environmental point of view

Reference 4

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:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)

GLP compliance:

not specified

Specific details on test material used for the study:

analytical grade and purchased from Merck and Fluka.

Inoculum or test system:

other: activated sludge with adaptation time either 5 or 30 days

Details on inoculum:

The inoculum was either non-adapted activated sludge collected at the municipal water treatment plant in Prague or an activated sludge adapted at different sludge age in the range of 5–30 days, which corresponds to the relations in medium- to low-load biological water treatment plants

Initial conc.:

50 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Two methods were combined for evaluating the complete biodegradability: the method of assaying dissolved organic carbon (EN ISO 7827) suitable for assessing ready biodegradability (X0 1⁄4 30 mg l-1, S01⁄4 DOC 50 mg l-1) and the Zahn-Wellens Test (EN ISO 9888) for assessing potential biodegradability (X0 1⁄4 30 mg l-1, S01⁄4 DOC 50 mg l-1).

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (DOC removal)

Value:

< 20

Sampling time:

28 d

Details on results:

All complexing agents based on tetra(penta)sub- stituted ethylenedi(tri)amine or propylenediamine with –CH2COOH substituents (EDTA, DTPA, HEDTA) were biologically stable even after a prolonged adaptation of the activated sludge up to age 30 days.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The susceptibility of ethylenediamine derivatives to biodegradation depends on the character and num- ber of nitrogen atoms and substituents in the molecule. The most stable are complexing agents containing in the molecule two and more tertiary nitrogen atoms and four or more carboxymethyl groups as substituents (e.g. EDTA, DTPA, HEDTA, PDTA). In terms of biological water treatment and spontaneous self- purification in surface water, these compounds belong among poorly biodegradable substances.

Executive summary:

Biological degradability of ethylenediamine derivatives depends on the type and number of substituents. The susceptibility to biodegradation decreases in the sequence of substituents –COCH3, –CH3, –C2H5, –CH2CH2OH, –CH2COOH and with polysubstitution. The biodegradability depends also on the kind and number of nitrogen atoms. Complexing agents with a single-nitrogen atom in the molecule (e.g. NTA) succumb relatively readily to biodegradation whereas, compounds with two or more tertiary amino groups are biologically highly stable and do not undergo biodegradation even in experiments with activated sludge adapted at an age of up to 30 days (EDTA, DTPA, PDTA, HEDTA). A lowering of the degree of substitution brings about an increased susceptibility to biodegradation. This holds, e.g., for replacement of tertiary amino groups with secondary ones; thus the symmetrically disubstituted ethylenediamine-N,N0-diacetic acid (EDDA) possesses still sufficient complexing ability while belong- ing already to the group of potentially degradable substances.

Reference 5

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:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 A (Inherent Biodegradability: Modified SCAS Test)

Qualifier:

according to guideline

Guideline:

ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)

Qualifier:

according to guideline

Guideline:

other: EN 29888

GLP compliance:

not specified

Specific details on test material used for the study:

analytical grade and purchased from Merck and Fluka.

Inoculum or test system:

other: activated sludge with adaptation time either 5 or 30 days

Details on inoculum:

Activated sludge suspended solids 200 mg/l, non-adapted and adapted under different mean biomass retention time sludge age) in days was the inoculum. The adaptation procedure was described previously Pitter and S ykora, 1996). Test parameter was % removal of DOC Dt ) and the test period was at least 28 d.
Experiments were carried out with non-adapted activated sludge and also with adapted activated sludge at sludge age within 5 d corresponding to usual wastewater treatment plants) and 30 d corre- sponding to aerobic sludge stabilization process).

Duration of test (contact time):

28 d

Initial conc.:

50 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

The organic compound was the sole source of organic carbon and energy for microorganisms.
It must be remembered that the concentration of complexing agents that can be complexed by metals is limited by stoichiometric considerations. Usually 1 mol EDTA and related compounds can complex a maximum of 1 mol of the metal. Inorganic composition of the bi- ological medium used was: Ca 0.25 mmol/l, Mg 0.1 mmol/l and Fe III) 0.001 mmol/l. Initial concentration of test substances approximately corresponds to 100 mg/ l, 0,34 mmol/l, respectively. This means that the for- mation of very stable Fe III) complex may be neglected.

Reference substance:

benzoic acid, sodium salt

Remarks:

sodium benzoate

Parameter:

% degradation (DOC removal)

Value:

>= 0 - <= 15

Sampling time:

28 d

Details on results:

All the above-mentioned chelating agents EDTA, DTPA, HEDTA, PDTA) with two or three tertiary ni- trogen atoms and hydroxyethyl or carboxymethyl groups in the molecule were stable under experimental conditions. DOC removal varied within 0% and 15%. The infl̄uence of the sludge age up to 30 d was not observed.

Tetrasubstituted derivatives with two tertiary nitrogen atoms and carboxymethyl- or 2-hydroxyethylgroups in the molecule (typical complexing agents EDTA, DTPA, PDTA, HEDTA) are biologically stable.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The biological degradability (Zahn-Wellens test, OECD 302A) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Tetrasubstituted derivatives with two tertiary nitrogen atoms and carboxymethyl- or 2-hydroxyethylgroups in the molecule typical complexing agents EDTA, DTPA, PDTA, HEDTA) are biologically stable.

Executive summary:

The biological degradability (Zahn-Wellens test) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Mixed bacterial culture (activated sludge) was used as inoculum (non-adapted sludge and sludge adapted at different mean biomass retention time, the so-called sludge age). Biodegradability of ethylene(propylene)di(tri)amine-based complexing agents depends on the character and number of substituents and nitrogen atoms in the molecule. Tetra penta)substituted derivatives with two or more tertiary nitrogen atoms and carboxymethyl or 2-hydroxyethyl groups in the molecule EDTA, DTPA, PDTA, HEDTA) are very stable from an environmental point of view

Reference 6

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:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

ISO 9888 Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Static test (Zahn-Wellens method)

GLP compliance:

not specified

Specific details on test material used for the study:

analytical grade and purchased from Merck and Fluka.

Inoculum or test system:

other: activated sludge with adaptation time either 5 or 30 days

Details on inoculum:

The inoculum was either non-adapted activated sludge collected at the municipal water treatment plant in Prague or an activated sludge adapted at different sludge age in the range of 5–30 days, which corresponds to the relations in medium- to low-load biological water treatment plants

Initial conc.:

50 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Two methods were combined for evaluating the complete biodegradability: the method of assaying dissolved organic carbon (EN ISO 7827) suitable for assessing ready biodegradability (X0 1⁄4 30 mg l-1, S01⁄4 DOC 50 mg l-1) and the Zahn-Wellens Test (EN ISO 9888) for assessing potential biodegradability (X0 1⁄4 30 mg l-1, S01⁄4 DOC 50 mg l-1).

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (DOC removal)

Value:

< 20

Sampling time:

28 d

Details on results:

All complexing agents based on tetra(penta)sub- stituted ethylenedi(tri)amine or propylenediamine with –CH2COOH substituents (EDTA, DTPA, HEDTA) were biologically stable even after a prolonged adaptation of the activated sludge up to age 30 days.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The susceptibility of ethylenediamine derivatives to biodegradation depends on the character and num- ber of nitrogen atoms and substituents in the molecule. The most stable are complexing agents containing in the molecule two and more tertiary nitrogen atoms and four or more carboxymethyl groups as substituents (e.g. EDTA, DTPA, HEDTA, PDTA). In terms of biological water treatment and spontaneous self- purification in surface water, these compounds belong among poorly biodegradable substances.

Executive summary:

Biological degradability of ethylenediamine derivatives depends on the type and number of substituents. The susceptibility to biodegradation decreases in the sequence of substituents –COCH3, –CH3, –C2H5, –CH2CH2OH, –CH2COOH and with polysubstitution. The biodegradability depends also on the kind and number of nitrogen atoms. Complexing agents with a single-nitrogen atom in the molecule (e.g. NTA) succumb relatively readily to biodegradation whereas, compounds with two or more tertiary amino groups are biologically highly stable and do not undergo biodegradation even in experiments with activated sludge adapted at an age of up to 30 days (EDTA, DTPA, PDTA, HEDTA). A lowering of the degree of substitution brings about an increased susceptibility to biodegradation. This holds, e.g., for replacement of tertiary amino groups with secondary ones; thus the symmetrically disubstituted ethylenediamine-N,N0-diacetic acid (EDDA) possesses still sufficient complexing ability while belong- ing already to the group of potentially degradable substances.

Description of key information

The chelating agents have been shown to be only inherently biodegradable (Pitter et al. 2001, Sykora et al. 2001). These chelating agents form stable complexes with metal ions and the biodegradability of the metal chelate is therefore not expected to be higher compared to the individual chelating agents.

The metal chelate is therefore expected to be not readily biodegradable but inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater