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Environmental fate & pathways

Additional information on environmental fate and behaviour

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Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
10 January 1991 to 7 June 1991
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable study report which meets basic scientific principles

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: 162-1
Principles of method if other than guideline:
The objective is to test whether DE-498 has a shorter half-life at high soil pH and longer half-life in soils with high organic matter content.
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report):DE-498

- Radiochemical purity (if radiolabelling):96%

- Name of test material (as cited in study report): DE-498

- Analytical purity: 99.6%

- Lot/batch No.: AGR240043

Results and discussion

Any other information on results incl. tables

In Appling Course and Commerce soils, DE-498 degraded with pseudo-first order half lives, based on initial rate data, of 27 and 42 days, respectively. No accumulation of metabolites above 10% of the applied radioactivity were observed, and DE-498 became increasingly bound to soil organic matter with time. It is unlikely that the material contained in the bound fraction of the soil (i.e., extractable only by caustic) is available to the environment for plant uptake or other processes.

Applicant's summary and conclusion

Conclusions:
It is unlikely that the DE-498 contained in the bound fraction of the soil (i.e., extractable only by caustic) is available to the environment for plant uptake or other processes. The parent material should be the only aerobic analyte of concern for future field studies.
Executive summary:

The degradation of DE-498, uniformly 14C-labeled in the aniline portion of the molecule, was studied in Appling Coarse sandy clay loam and Commerce silt loam soils. The chemical was applied at 0.07 ppm, corresponding to the maximum field application rate of 79 grams per hectare, as well as the concentration found in field dissipation studies. Under aerobic conditions at 25 degrees C, DE-498 degraded with apparent first order half lives, based on initial rate data, of 27 and 42 days, in the Appling and Commerce soils, respectively. These results are comparable to data obtained with DE-498 radiolabeled on the pyrimidine portion of the molecule. No accumulation of metabolites above 10% of applied DE-498 was observed and DE-498 became increasingly bound to soil organic matter with time. Thus, the parent should be the only aerobic analyte of concern for future field studies. Overall 14C accountability averaged greater than 94% of the applied activity.