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Environmental fate & pathways

Biodegradation in soil

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Administrative data

Endpoint:
biodegradation in soil
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed to modern guidelines and described in sufficient detail.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: EPA 835.4100 (2009)
GLP compliance:
yes
Test type:
laboratory

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
3.19 MBq/mg
Radiolabelling:
yes

Study design

Oxygen conditions:
aerobic
Soil classification:
USDA (US Department of Agriculture)
Soil propertiesopen allclose all
Soil no.:
#1
Soil type:
clay loam
% Clay:
33
% Silt:
38
% Sand:
29
% Org. C:
ca. 3.1
pH:
6.6
CEC:
23.2 meq/100 g soil d.w.
Bulk density (g/cm³):
0.92
Soil no.:
#2
Soil type:
sandy loam
% Clay:
17
% Silt:
13
% Sand:
70
% Org. C:
1.52
pH:
6.8
CEC:
16.2 meq/100 g soil d.w.
Bulk density (g/cm³):
1.05
Soil no.:
#3
Soil type:
loamy sand
% Clay:
8
% Silt:
6
% Sand:
86
% Org. C:
1.2
pH:
5.6
CEC:
10.5 meq/100 g soil d.w.
Bulk density (g/cm³):
1.15
Soil no.:
#4
Soil type:
loam
% Clay:
17
% Silt:
44
% Sand:
39
% Org. C:
1.3
pH:
7.2
CEC:
12.9 meq/100 g soil d.w.
Bulk density (g/cm³):
0.99
Initial test substance concentrationopen allclose all
Soil No.:
#1
Initial conc.:
0.578 - 0.584 ppm
Based on:
test mat.
Soil No.:
#2
Initial conc.:
0.568 - 0.574 ppm
Based on:
test mat.
Soil No.:
#3
Initial conc.:
0.566 - 0.57 ppm
Based on:
test mat.
Soil No.:
#4
Initial conc.:
0.514 - 0.517 ppm
Based on:
test mat.
Experimental conditionsopen allclose all
Soil No.:
#1
Temp.:
20
Humidity:
75% 1/3 bar
Microbial biomass:
73.04 mg C/100g
Soil No.:
#2
Temp.:
20
Humidity:
75% 1/3bar
Microbial biomass:
50.72 mg C/100g
Soil No.:
#3
Temp.:
20
Humidity:
75% 1/3bar
Microbial biomass:
7.63 mg C/100g
Soil No.:
#4
Temp.:
20
Humidity:
75% 1/3 bar
Microbial biomass:
35.50 mg C/100g

Results and discussion

Material (mass) balanceopen allclose all
Soil No.:
#1
% Recovery:
102.3
St. dev.:
2.4
Soil No.:
#2
% Recovery:
101.6
St. dev.:
2.5
Soil No.:
#3
% Recovery:
101.4
St. dev.:
2.6
Soil No.:
#4
% Recovery:
99.7
St. dev.:
2.4
% Degradationopen allclose all
Soil No.:
#1
% Degr.:
10.8
Parameter:
radiochem. meas.
Sampling time:
222 d
Soil No.:
#2
% Degr.:
7.8
Parameter:
radiochem. meas.
Sampling time:
222 d
Soil No.:
#3
% Degr.:
17.2
Parameter:
radiochem. meas.
Sampling time:
222 d
Soil No.:
#4
% Degr.:
ca. 10
Parameter:
radiochem. meas.
Sampling time:
221 d
Half-life / dissipation time of parent compoundopen allclose all
Soil No.:
#1
DT50:
70 d
St. dev.:
0.899
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: DT90 233 days
Soil No.:
#2
DT50:
58.2 d
St. dev.:
0.872
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: DT90 194 days
Soil No.:
#3
DT50:
72.2 d
St. dev.:
0.504
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: DT90 240 days
Soil No.:
#4
DT50:
59.2 d
St. dev.:
0.685
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: DT90 197 days
Transformation products:
yes
Identity of transformation productsopen allclose all
No.:
#1
Reference
Reference substance name:
Unnamed
IUPAC name:
desamino amicarbazone
No.:
#2
Reference
Reference substance name:
Unnamed
IUPAC name:
N-methyl desamino amicarbazone
No.:
#3
Reference
Reference substance name:
Unnamed
IUPAC name:
Decarboxamide
Details on transformation products:
#1 (max) 59.4%; #2 (max) 8.6%; #3 (max) 0.2%, D1 (max) 24.1% (loamy sand soil), <2% other soils; D2 (max) 5.6%
Evaporation of parent compound:
yes
Volatile metabolites:
yes
Residues:
yes
Details on results:
Bound Residues reached a maximum of 49.5% then declined to a maximum of 33.8% at 222 days. Max 3.3% volatiles (CO2).

Applicant's summary and conclusion

Conclusions:
A comprehensive degradation study in four soils with a mean DT50 of 64.9 days.
Executive summary:

A well documented study on the route and rate of Amicarbazone in four soils. The DT50s ranged from 58.2 to 72.2 days with a mean of 64.9 days. Amicarbozone degraded to 3 known metabolites; desamino amicarbazone (max. 59.4%), N-methyl desamino amicarbazone (max. 8.6%) and decarboxamide (max. 0.2%). D1 was formed in some of the soils at <2% but had a maximum of 24% in the loamy sand soil. D2 was formed at a maximum of 5.6%.

Bound residues reached a maximum of 33.8% at termination of the study and mineralisation was <5%.

Overall mass balance was 99.7 ± 2.4% to 102.3 ± 2.4% for all samples.