Edetic acid

Biodegradation in soil

Link to relevant study record(s)

Reference

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.

Description of key information

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

Additional information

Two studies are available investigating the biodegradability of edetic acid in soil. 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 and thus not persistent in the terrestrial compartment.