Chlorimuron ethyl

Phototransformation in soil

Administrative data

Endpoint:

phototransformation in soil

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

Year:

1985

Report date:

1985

Materials and methods

Principles of method if other than guideline:

Radiolabeled test materials (with the radiolabel either on the phenyl or on the pyrimidine moiety) were applied to Flanagan silt loam soil and exposed to natural sunlight for 32 days (mid-August through mid-September. 1985).

GLP compliance:

no

Test material

Test material information

Constituent 1

Test material form:

solid

Details on test material:

Purity: not reported

Radiolabelling:

yes

Study design

Analytical monitoring:

no

Analytical method:

liquid chromatography

Details on soil:

Characteristics of Flanagan soil (Silt loam): Sand = 4%; Silt = 81%; Clay = 15%; Organic matter = 4.3% and pH = 5.8 and Cation exchange capacity = 23.2 meg/100g

Light source:

other: Four photolysis box units

Light spectrum: wavelength in nm:

285 - 2 800

Duration of test at given test condition

Duration:

32 d

Reference substance:

no

Dark controls:

yes

Results and discussion

Dissipation half-life of parent compound

Dissipation half-life of parent compound 1

Key result

DT50:

20 d

Test condition:

irradiated sample

Dissipation half-life of parent compound 2

Key result

DT50:

> 43 - < 46 d

Test condition:

dark controls

Transformation products:

yes

Identity of transformation products

Identity of transformation products 1

No.:

#1

Reference

Reference substance name:

Unnamed

Identity of transformation products 2

No.:

#2

Reference

Reference substance name:

Unnamed

Any other information on results incl. tables

Composition and distribution of radioactivity recovered from soil

Photolysis samples treated with [pyrimidine-2-14c] DPX-F6025 (percent of total 14C normalized to total 14C recovered equal to 100%)

 

Day	Solar Energy (watt-hr/m2)	DPX-F6025	Pyrimidinamine (a)	Unknown (b)	Other (c)	Unextracted
0	0	95	2	0	2	Not determined
7	30,513	72	13	0	7	3
14	65,316	66	12	0	10	8
21	98,802	44	37	0	2	10
32	154,497	31	50	0	0	12

 

Day	Solar Energy (watt-hr/m2)	DPX-F6025	Pyrimidinamine (a)	Unknown (b)	Other (c)	Unextracted
7 (Dark)	-----	87	8	0	2	1
14 (Dark)	-----	84	4	9	1	2
21 (Dark)	-----	66	14	14	1	2
32 (Dark)	-----	60	17	18	1	4

(a) 4-Chloro-6-methoxy-2-pyrimidinamine

(b) Unidentified product appearing only in dark control samples. The product failed to form in an

     attempted large scale preparation to obtain a sample for characterization.

(c)Sum of unidentified labeled products, none of which is more than3%.

 

Composition and distribution of radioactivity recovered soil from photolysis samples treated with [phenyl-14c] DPX-F6025

(percent of total 14C normalized to total 14C recovered equal to 100%)

 

Day	Solar Energy (watt-hr/m2)	DPX-F6025	Sulfonamide (d)	Saccharin	CO2	Other (e)	Unextracted
0	0	92	1	3	---	2	Not determined
7	30,513	74	12	3	0	4	4
14	65,316	46	31	7	1	1	8
21	98,802	48	35	2	1	2	8
32	154,497	29	48	3	2	1	12

 

Day	Solar Energy (watt-hr/m2)	DPX-F6025	Sulfonamide (d)	Saccharin	CO2	Other (e)	Unextracted
7 (Dark)	-----	80	9	3	0	3	3
14 (Dark)	-----	71	18	4	0	1	5
21 (Dark)	-----	60	30	1	0	2	6
32 (Dark)	-----	55	35	1	0	2	5

 

(d) Ethyl 2-aminosulfonylbenzoate

(e)Sum of unidentified labeled products, none of which is more than3%.

Applicant's summary and conclusion

Conclusions:

Degradation of the test substance occurred approximately twice as fast in the presence of sunlight compared to the dark controls: the first half-life was approximately 20 days in irradiated samples vs. 43-46 days in the dark controls. The major radiolabeled compounds were 4-chloro-6-methoxy- 2-pyrimidinamine and ethyl 2-amino-sulfonylbenzoate. These are the expected products of hydrolytic cleavage of the sulfonylurea bridge of the test substance.

Executive summary:

Radiolabeled test materials (with the radiolabel either on the phenyl or on the pyrimidine moiety) were applied to Flanagan silt loam soil and exposed to natural sunlight for 32 days (mid-August through mid-September, 1985).

Degradation of the test substance occurred approximately twice as fast in the presence of sunlight compared to the dark controls: the first half-life was approximately 20 days in irradiated samples vs. 43-46 days in the dark controls. The major radiolabeled compounds were 4-chloro-6-methoxy-2-pyrimidinamine and ethyl 2-amino-sulfonylbenzoate. These are the expected products of hydrolytic cleavage of the sulfonylurea bridge of the test substance.