Trisodium 2-(carboxylatomethyl(2-hydroxyethyl)amino)ethyliminodi(acetate)

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data available

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2009

Materials and methods

Test guideline

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:

no

Remarks:

University study, not GLP

Test type:

laboratory

Test material

Test material information

Constituent 1

Reference substance name:

Edetic acid

EC Number:

200-449-4

EC Name:

Edetic acid

Cas Number:

60-00-4

Molecular formula:

C10 H16 N2 O8

IUPAC Name:

2,2',2'',2'''-(ethane-1,2-diyldinitrilo)tetraacetic acid

Details on test material:

14C-EDTA (0.9 mg, 1.85 MBq, Sigma, St. Louis, USA)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no data available

Radiolabelling:

yes

Study design

Oxygen conditions:

aerobic

Soil classification:

not specified

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 properties (physical and chemical characteristics of the selected soils:

Soil properties Keith Booleroo Changsha
pH (1:5 soil/water) 5.4 7.3 7.9
MWHCa (%) 30.2 40.7 49.4
Moisture (%) 1.3 2.2 1.3
Organic Carbon (%) 0.6 1.0 1.4
Clay (%) 12 23 13
Silt (%) 2 22 38
Sand (%) 40 56 47

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.

Results and discussion

% Degradation

% Degr.:

> 0 - < 20

Parameter:

CO2 evolution

Sampling time:

20 d

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

Applicant's summary and conclusion

Conclusions:

on average 14 % of EDTA was degraded after 20 d.

Executive summary:

The rate of EDTA degradation was determined in three natural soils after 20 d of exposure. 14 % of a 2 mmol/kg EDTA treatment (equivalent to 584 mg/kg soil) was readily degraded in the three used soils under test conditions.