Chlorimuron ethyl

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil, other

Remarks:

Terrestrial dissipation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Pesticide Assessment Guidelines, Subdivision N, Chemistry: Environmental Fate, National Technical Information Service Document No. PB 83-143973, October, 1982.

GLP compliance:

no

Test type:

laboratory

Test material

Test material information

Constituent 1

Reference substance name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

EC Number:

618-690-2

Cas Number:

90982-32-4

Molecular formula:

C15H15ClN4O6S

IUPAC Name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

Test material form:

solid

Remarks:

White

Details on test material:

95 to >99% purity

Specific details on test material used for the study:

Phenyl-14C(U) labeled DPX-F6025 (Specific activity of 58.5 µCi/mg and radiochemical purity of 99%)
Pyrimidine-2-14C labeled DPX-F6025 (Specific activity of 33.3 µCi/mg and radiochemical purity of 98%)

Radiolabelling:

yes

Study design

Soil properties

Soil properties 1

Soil no.:

#1

Soil type:

other: Keyport Silt Loam

% Clay:

17

% Silt:

62

% Sand:

21

% Org. C:

2.8

pH:

6.4

CEC:

8.2 meq/100 g soil d.w.

Soil properties 2

Soil no.:

#2

Soil type:

other: Flanagan Silt loam

% Clay:

19

% Silt:

69

% Sand:

12

% Org. C:

6.7

pH:

6.7

CEC:

37.8 meq/100 g soil d.w.

Soil properties 3

Soil no.:

#3

Soil type:

other: Dundee Silt Loam

% Clay:

18

% Silt:

74

% Sand:

8

% Org. C:

1.4

pH:

6.4

CEC:

5.3 meq/100 g soil d.w.

Soil properties 4

Soil no.:

#4

Soil type:

other: Norfolk Loamy Sand

% Clay:

4

% Silt:

18

% Sand:

78

% Org. C:

1.2

pH:

5.9

CEC:

3.1 meq/100 g soil d.w.

Duration of test (contact time)

Duration of test (contact time) 1

Soil No.:

#1

Duration:

78 wk

Duration of test (contact time) 2

Soil No.:

#2

Duration:

78 wk

Duration of test (contact time) 3

Soil No.:

#3

Duration:

78 wk

Duration of test (contact time) 4

Soil No.:

#4

Duration:

78 wk

Parameter followed for biodegradation estimation:

radiochem. meas.

Results and discussion

Half-life / dissipation time of parent compound

DT50:

> 1 - < 6 wk

Type:

other: Initial half life for all the soils

Transformation products:

yes

Remarks:

Demethyl-test substance, 4-chIoro-6-methoxy-pyrimidin-2-yl amine, sulphonamide, saccharin

Applicant's summary and conclusion

Conclusions:

The test substance has first-order half-life of 1-6 weeks, decomposing either by hydrolysis or by demethylation

Executive summary:

The terrestrial dissipation of the test substance was studied for 78 weeks at 4 sites. The test substance was applied to bare soil isolated in stainless steel cylinders at a rate corresponding to 2 oz/A. Analysis of the soils after various exposure intervals indicated that the test substance had a first-order half-life of 1-6 weeks, with the longer half-life observed on soil with high cation exchange capacity and organic matter content. The test substance decomposed either by hydrolysis or by demethylation. The test substance and its metabolites exhibited significant mobility only in soil with high (78%) sand content.

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