Registration Dossier

Administrative data

Endpoint:
other distribution data
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP, available as unpublished report, minor restrictions in design and/or reporting but otherwise adequate for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1977
Report Date:
1977

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The mobility of 14C-labeled test substance was determined by soil thick-layer chromatography. In a first experiment test substance was applied to 4 soils: Gore Hill (a calcareous clay loam), Lily Field (a coarse sand), Pear Tree (a coarse sandy loam), and Blackborough (a peat). On applying 32 cm ‘rain’ the distance of leaching of the test substance was determined. In a second experiment using Lilly field Soil, different concentrations were applied to separate chromatograms.
GLP compliance:
no
Type of study:
soil leaching
Media:
soil - biota

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Results and discussion

Any other information on results incl. tables

EXPERIMENT 1:

On applying 32 cm ‘rain’ the peak concentrations of the leached test substance was at 10 cm, 7 cm, and 2 cm in Gore Hill, Pear Tree, and Blackborough soils respectively. Peak concentrations of leached test substance was below 20 cm for Lilly Field soil; 73.4% of applied test substance was found below this level. Under the same conditions atrazine which has a moderate mobility in soil was leached 5-10 cm in Gore Hill, Lily Field, Pear Tree and Blackborough soils; at the level peak concentrations were observed. Leaching in the Lily Field soil was much less than for previous studies which was about 20 cm. An application of 167.6 µg/chromatogram of 14C-labelled test substance (equivalent to 6.7 kg/ha) gave a maximum of 0.1 µg/mL (<1.1% of applied) in leachates of the Gore Hill, Pear Tree and Blackborough soils while this was 1.38 µg/mL (38% of applied) for the Lily Field soil.

EXPERIMENT 2:

It was established that 98.34% of the radioactivity was the test substance. Since the purity of the compound at the commencement of the experiment was 97.04%, it can be concluded that no apparent degradation products were present in the leachates. The peak concentration of leached test substance was at a level greater than 20 cm at both rates of application (11.39 and 182.2 µg) with 51.5% and 57.5% respectively leaching below 20 cm. The pattern of movement was similar at both the low and high rates of application; movement was slightly less at the lower rate. Applications of 11.39 µg and 182.2 µg/chromatogram of 14C-labelled test substance (equivalent to 0.46 and 7.29 kg/ha) gave 0.05 µg/mL (14.7% of applied) and 1.43 µg/mL (26% of applied) respectively in the leachates. The lowest rate (0.46 kg/ha) studied in these experiments was approximately 1000 times more than the normal rate of application (2.5 g/ha); the specific activity of the test substance determined the lowest concentration which could be studied. As the concentration of a chemical in soil decreases, its adsorption coefficient tends to increase, thus leaching decreases. Also under field conditions the peak concentration of a chemical is normally less than is observed in laboratory soil chromatogram and column experiments. Thus from a normal rate of application, the concentration of the test substance in solution which has percolated through the top soil will be less than 0.0001 µg/mL.

Applicant's summary and conclusion

Conclusions:
It is concluded that the test substance has a moderately mobility in clay loam, sandy loam, and peat soils and a high mobility in coarse sandy soils i.e. with less than 1.5% organic matter. From a normal rate application (2.5 g/ha) the concentration of the test substance in soil solution which has percolated through the top soil will be less than 0.0001 µg/mL.
Executive summary:

The mobility of 14C- labeled test substance was determined by soil thick-layer chromatography. In the first experiment 167.6 µg/chromatogram (6.7kg/ha) of the test substance was applied, and 4 soils were used Gore Hill (a calcareous clay loam), Lily Field (a coarse sand), Pear Tree (a coarse sandy loam), and Blackborough (a peat). Atrazine, a moderately mobile herbicide, was studies under the same conditions as a standard. On applying 32 cm ‘rain’ the distance of leaching of the test substance as measured by peak concentrations were > 20 cm, 10 cm, >7 cm and 2 cm in Lily Field, Gore Hill, Pear Tree and Blackborough soils, respectively.

Under the same conditions the leaching of atrazine reached peak concentration at a distance of 5 to 10 cm. In a second experiment using Lilly field Soil, 182.2 µg and 11.39 µg were applied to separate chromatograms after leaching, the distribution of the test substance on chromatograms and in leachates was similar to that of the first study. The 14C in these leachates was shown by TLC to be the test substance.

It is concluded that the test substance has a moderately mobility in clay loam, sandy loam, and peat soils and a high mobility in coarse sandy soils i.e. with less than 1.5% organic matter. From a normal rate application (2.5 g/ha) the concentration of the test substance in soil solution which has percolated through the top soil will be less than 0.0001 µg/mL.