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Administrative data

Endpoint:
biodegradation in soil
Type of information:
migrated 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:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1978

Materials and methods

Principles of method if other than guideline:
Degradation units, each containing 20 g (dry-weight) soil, spiked with either test or reference substance, sparged with CO2-free air and the off-gas passed through CO2 absorbent scrubbers. The C-14 evolved measured by liquid scintillation counting.
GLP compliance:
no
Test type:
laboratory

Test material

Constituent 1
Chemical structure
Reference substance name:
[ethane-1,2-diylbis[nitrilobis(methylene)]]tetrakisphosphonic acid
EC Number:
215-851-5
EC Name:
[ethane-1,2-diylbis[nitrilobis(methylene)]]tetrakisphosphonic acid
Cas Number:
1429-50-1
Molecular formula:
C6H20N2O12P4
IUPAC Name:
{ethane-1,2-diylbis[nitrilobis(methylene)]}tetrakis(phosphonic acid)
Radiolabelling:
yes

Study design

Soil propertiesopen allclose all
Soil no.:
#1
Soil type:
other: St. Charles Ray Silt Loam
Soil no.:
#2
Soil type:
other: Meramec river bank
Details on soil characteristics:
SOIL CHARACTERISTICS:
Source: St. Charles Ray-Silt Loam
pH: 7.05
% organic carbon: 0.56
Water content: 0.14 g/g (dry-weight basis)
Water Holding Capacity: 0.45 g/g

Source: Meramec river bank soil
pH: 7.70
% organic carbon: 0.70
Water content: 0.06 g/g (dry-weight basis)
Water Holding Capacity: 0.39 g/g
Duration of test (contact time)open allclose all
Soil No.:
#1
Duration:
148 d
Soil No.:
#2
Duration:
148 d
Experimental conditionsopen allclose all
Details on experimental conditions:
TEST DETAILS: St. Charles Ray-silt loam - was sieved through a 2 mm screen and the water content adjusted with either distilled water or a dilute sodium azide solution (to approximate a sterile control). Degradation units, each containing 20 g (dry-weight) soil, were spiked with either test substance or linear dodecylbenzene sulfonate (LAS) at a nominal level of 10 µg/g (for test substance, as active acid). Each soil unit was sparged with CO2-free air and the off-gas passed through two scrubbers each containing 5 ml of the CO2 absorbent (monoethanolamine-ethylene glycol) monoethyl ether 1:7 (v/v) solution. Periodically, the first scrubber was removed, the second scrubber moved to position one and replaced with a fresh scrubber. The C-14 evolved was then measured by liquid scintillation counting using a Mark III Liquid Scintillation Spectrometer (Model 6880, Searle Analytic, Inc.). The percent C-14 evolved was calculated from the disintegrations per minute and the initial C-14 charged to each unit.

Results and discussion

% Degradationopen allclose all
Soil No.:
#1
% Degr.:
68.66
Parameter:
radiochem. meas.
Remarks:
14CO2 evolution
Sampling time:
148 d
Soil No.:
#2
% Degr.:
72.55
Parameter:
radiochem. meas.
Remarks:
14CO2 evolution
Sampling time:
148 d
Soil No.:
#1
% Degr.:
18.07
Parameter:
radiochem. meas.
Remarks:
14CO2 evolution (sterile control)
Sampling time:
148 d
Soil No.:
#2
% Degr.:
3.11
Parameter:
radiochem. meas.
Remarks:
14CO2 evolution (sterile control)
Sampling time:
148 d
Half-life / dissipation time of parent compound
Type:
(pseudo-)first order (= half-life)
Transformation products:
not measured
Evaporation of parent compound:
no
Volatile metabolites:
no

Any other information on results incl. tables

Table 1: Percent degradation values (14CO2 evolved, % theory)

Type of suspension

% degradation at sampling time (days)

2

6

12

16

21

28

35

43

58

72

86

100

114

128

148

Reference substance (LAS) Microbial

0.03

0.14

2.20

4.53

7.69

11.46

15.68

20.49

29.44

36.34

41.92

46.59

50.41

53.60

56.97

Reference substance (LAS) Sterile

0

0.02

0.05

0.05

0.05

0.07

0.07

0.07

0.07

0.08

0.08

0.08

0.08

0.08

0.10

 

 

 

 

 

 

 

 

EDTMP - St Charles Ray silt loam - active

23.36

29.16

34.20

37.11

40.08

43.05

45.76

48.77

53.44

56.96

59.94

62.54

64.64

66.39

68.66

EDTMP - St Charles Ray silt loam - Sterile

11.86

14.60

15.56

15.95

16.50

16.90

17.18

17.36

17.60

17.77

17.87

17.93

17.98

18.01

18.07

 

 

 

 

 

 

 

 

 

 EDTMP - Meramec river bank - active  13.50 20.76   27.30  31.43  36.40  41.36  45.78  50.64  56.91  61.06  64.15  66.66  68.69  70.43  72.55
 EDTMP - Meramec river bank - sterile  1.36  1.39  1.71  2.14 2.25  2.35  2.42  2.48  2.60  2.70  2.78  2.86  2.93  2.99  3.11

 

The data suggest that no induction period is required before degradation occurs.

Applicant's summary and conclusion

Conclusions:
Soil biodegradation rate of 68-73% over 148d in two active soils was determined in a reliable study conducted according to generally accepted scientific principles.

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