Diammonium dihydrogen ethylenediaminetetraacetate

Biodegradation in soil

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in soil, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Laboratory study on biodegradation of EDTA in different agricultural soils over an incubation time of 4 to 45 weeks.

GLP compliance:

no

Test type:

laboratory

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: 4813

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: 99%
- Specific activity: 2.54 mCi/mM
- Locations of the label: 14C-carboxyl-EDTA

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

not specified

Year:

1977

Soil no.:

#1

Soil type:

other: Brookston loam

pH:

6.8

Soil no.:

#2

Soil type:

other: Conover sandy loam

pH:

6.7

Soil no.:

#3

Soil type:

other: Spinks loamy fine sand

pH:

6.4

Soil no.:

#4

Soil type:

other: Miami sandy loam

pH:

6

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
All soil samples were collected and stored in sealed plastic bags at 2 °C. All samples were taken in Michigan and each were a composite of subsamples collected at three locations within a 10 m2 area.

Soil No.:

#1

Duration:

4 - 45 wk

Soil No.:

#2

Duration:

4 - 45 wk

Soil No.:

#3

Duration:

4 - 15 wk

Soil No.:

#4

Duration:

4 - 15 wk

Soil No.:

#1

Initial conc.:

2.5 - 4.5 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#2

Initial conc.:

2.5 - 4.5 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#3

Initial conc.:

2.5 - 4.5 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#4

Initial conc.:

2.5 - 4.5 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

radiochem. meas.

Details on experimental conditions:

25 g fresh weight of soil was added to 125 mL Erlenmeyer flasks that had been fitted with rubber stoppers which supported a 2 mL plastic beaker containing 1 mL of 1N NaOH. The soils were adjusted to ~ field capacity. Microdrops of neutralized 14C-EDTA solutions were randomly distributed over the soil surface using a 28-gage needle on a 100 µL syringe. All soils were sealed and incubated at room temperature (25-27 °C). All of the reported data are means from duplicate or triplicate.

Key result

Soil No.:

#1

% Degr.:

65

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

45 wk

Key result

Soil No.:

#2

% Degr.:

70.5

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

45 wk

Soil No.:

#1

% Degr.:

44.5

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

15 wk

Soil No.:

#2

% Degr.:

43.5

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

15 wk

Soil No.:

#3

% Degr.:

32

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

15 wk

Soil No.:

#4

% Degr.:

44.5

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

15 wk

Soil No.:

#1

% Degr.:

11

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

4 wk

Soil No.:

#2

% Degr.:

12.2

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

4 wk

Soil No.:

#3

% Degr.:

11.3

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

4 wk

Soil No.:

#4

% Degr.:

10

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

4 wk

Transformation products:

no

Evaporation of parent compound:

no

Volatile metabolites:

no

Residues:

no

Details on results:

14C-EDTA was (slowly) biodegraded to 14CO2 by all soils (varying in pH and texture) tested from a major agricultural EDTA use area. No detectable quantities of intermediates accumulated under aerobic conditions.

Generally, the variation between duplicates/triplicates was < 8%.

Conclusions:

EDTA is (slowly) biodegradable in soils.

Reference 2

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

no data available

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

A defined amount of natural soil was incubated with 14C-labelled test material and 14Clabelled CO2 evolved through exposure period was collected and determined.

GLP compliance:

yes

Test type:

laboratory

Specific details on test material used for the study:

RADIOLABELLING INFORMATION (if applicable)
14C-EDTA (0.9 mg, 1.85 MBq, Sigma, St. Louis, MO).

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

not specified

Soil no.:

#1

Soil type:

other: Keith

% Clay:

12

% Silt:

2

% Sand:

40

% Org. C:

0.6

pH:

5.4

CEC:

8.64 other: cmol+/kg

Soil no.:

#2

Soil type:

other: Booleroo

% Clay:

23

% Silt:

22

% Sand:

56

% Org. C:

1

pH:

7.3

CEC:

13.9 other: cmol+/kg

Soil no.:

#3

Soil type:

other: Changsha

% Clay:

13

% Silt:

38

% Sand:

47

% Org. C:

1.4

pH:

7.9

CEC:

6.7 other: cmol+/kg

Details on soil characteristics:

Two uncontaminated soils from Keith and Booleroo in South Australia and a rice paddy soil from Changsha, China with past contamination from mining were selected for this study. The soils were collected in the field to a depth of 20 cm, air-dried and sieved to <2 mm.

Soil No.:

#1

Duration:

28 d

Soil No.:

#2

Duration:

28 d

Soil No.:

#3

Duration:

28 d

Soil No.:

#1

Initial conc.:

584 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#2

Initial conc.:

584 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#3

Initial conc.:

584 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on experimental conditions:

The soils were incubated at 50 +/- 5% of their maximum water holding capacity (MWHC) in the dark at 25 °C for 28 d to stimulate microbial activity. Working solutions of 14C-EDTA were prepared by spiking 0.1 mmol/l solutions of EDTA with 14C-EDTA (0.9 mg, 1.85 MBq, Sigma, St. Louis, MO).
After incubation, 0.5 ml of each 14C-labelled working solution was added to plastic vials containing 25 g of each soil by pipette, then mixed throughout the soil using a spatula to obtain spiking rates of 2 mmol/kg for EDTA (corresponding to 584 mg/kg soil) . Each vial was placed in a sealed 250 ml polypropylene jar and incubated at 25 °C in the dark for 20 d. All soil samples amended with different treatments were analysed in triplicate.

Key result

% Degr.:

> 0 - < 20

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

20 d

Remarks on result:

other: mean degradation of 14% over all soils

Transformation products:

not specified

Details on transformation products:

no data available

Evaporation of parent compound:

not specified

Volatile metabolites:

not specified

Residues:

not specified

Details on results:

on average 14 % of EDTA was readily degraded in all three soils.

Results with reference substance:

no data available

Reference 3

Endpoint:

biodegradation in soil: simulation testing

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Category justification document is attached in chapter 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Key result

% Degr.:

65

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

45 wk

Remarks on result:

other: EDTA

Remarks:

(loam)

Key result

% Degr.:

70.5

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

45 wk

Remarks on result:

other: EDTA

Remarks:

(sandy loam)

Key result

% Degr.:

> 0 - < 20

Parameter:

CO2 evolution

Remarks:

[14CO2]

Sampling time:

20 d

Remarks on result:

other: EDTA

Transformation products:

no

Description of key information

>= 65% degradation in 45 weeks (read across)

Additional information

Since no studies are available investigating the biodegradability of Diammonium dihydrogen ethylenediaminetetraacetate (CAS No. 20824-56-0) in soil, the assessment was based on studies conducted with subcategory 1 member edetic acid (CAS No. 60-00-4) in a read across approach. This is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Grouping of substance and read across approach. Further justification for suitability of read across between Subcategory 1 members is given within the category justification attached to chapter 13.

For the determination of biodegradation in soil non-standard investigations under various conditions show that EDTA can be biodegraded in soil under aerobic conditions. The rate of EDTA degradation was determined in different agricultural soils after 4 - 45 weeks of exposure. While degradation rate was 10-12% only after 4 weeks the degradation continued showing 32-45% degradation after 15 weeks and >= 65% after 45 weeks incubation time. This indicate that EDTA is (slowly) biodegradable in soil.

Based on the suitability of the read across approach this conclusion can also considered to be true for Diammonium dihydrogen ethylenediaminetetraacetate (CAS No. 20824-56-0).