Mecoprop

Field studies

Administrative data

Endpoint:

field studies dissipation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1986

Report date:

1986

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: FIFRA GUIDELINE NO. 164-1

Deviations:

no

GLP compliance:

yes

Type of measurement:

HPLC

Media:

Soil

Test material

Test material information

Constituent 1

Reference substance name:

Mecoprop

EC Number:

230-386-8

EC Name:

Mecoprop

Cas Number:

7085-19-0

Molecular formula:

C10H11ClO3

IUPAC Name:

2-(4-chloro-2-methylphenoxy)propanoic acid

Test material form:

not specified

Results and discussion

Any other information on results incl. tables

Data are presented for soil samples collected during the pre-application and post-application sampling intervals through day 60. Results include all top horizon, 0 - 5 cm core samples, 5 - 10 cm, 10 - 15 cm, and selected samples from the 15 - 20 cm horizon. A linear regression analysis correlating the natural logrithm of the mean measured test material soil concentration vs. sampling interval was performed. A half-life of test material residues in soil with and without turf was calculated to be 16.72 and 12.08 days, respectively.

Dissipation of the test material:  The chromatograms from analyses of the untreated plots again showed trace levels of the test material or an interfering component so that the concentrations ranged from 0.06 ppm to 0.35 ppm in one sub-plot. On the day of application (day 0), the concentrations of the test material in the soil from the treated turf sub-plots ranged from 0.16 ppm to 0.43 ppm. Extensive change had not occurred by day 1 but one underlying layer had a concentration of 0.19 ppm. Fourteen days after treatment, the levels of the test material in layer 1 had not decreased significantly and were in the range of 0.06 ppm to 0.30 ppm. In the same time frame, the concentrations in the underlying levels had not increased. By day 28 post-treatment, there was complete dissipation, as soil from treated sub-plots did not contain levels of test material in layers 1, 2 and 3 (< 0.05 ppm). On the day of treatment, the concentrations of the test material in the soil of layer 1 from the treated bare ground sub-plots ranged from 2.00 ppm to 4.52 ppm. Fourteen days after treatment, the levels of the test material in layer 1 had decreased and ranged from 0.10 ppm to 0.30 ppm. Twenty-eight days after treatment, the test material had not completely dissipated so that the concentrations still ranged from 0.06 ppm to 0.21 ppm. As in the case of the turf plots, the decrease in layer 1 did not induce an increase in the underlying layers, where except for low values of 0.06 ppm and 0.07 ppm at 60 days, measurable levels of test material were not present.

It can be concluded that the test material degraded in the soil from the Ohio site over the 60-day period after application. There was no significant mobility or movement of the test material from layer 1 to the layers beneath the top 10 cm layer. The presence of crop (turf) apparently affected the dissipation of the test material. In the presence of the turf there was complete dissipation after 28 days. In the soil of the bare ground, dissipation was almost complete after 60 days.

Applicant's summary and conclusion

Conclusions:

Under the conditions of the study the test material degraded in the soil from the Ohio site over the 60-day period after application. There was no significant mobility or movement of the test material from layer 1 to the layers beneath the top 10 cm layer. The presence of crop (turf) apparently affected the dissipation of the test material. In the presence of the turf there was complete dissipation after 28 days. In the soil of the bare ground, dissipation was almost complete after 60 days. A half-life of test material residues in soil with and without turf was calculated to be 16.72 and 12.08 days, respectively.

Executive summary:

The study was designed to follow the extent of dissipation and mobility of the test material under actual field conditions following application at maximum labelled rates for terrestrial crop use. At an experimental site in Ohio, four field plots were designated and treated: (1) one treated crop (turf), (2) one nontreated crop (turf), (3) one treated bare ground, and (4) one non-treated bare ground. Samples of soil were taken at increasing depths in 5 cm increments (layers) from the surface at specific time points after application. The samples were processed and were analysed for test material. In general, it can be concluded that test material degraded in the soil at the Ohio site over the 28-day period after application. There was no apparent mobility or movement of the test material to layers of soil beneath the top 10 cm layer. The presence of crop (turf) apparently affected the dissipation of test material. In the presence of the turf there was complete dissipation after 28 days, but in the soil of the bare ground low levels of test material were present at 28 days. Data were generated to show that the procedures used to process the layers of soil gave homogeneous and representative samples from individual sub-plots within the plots. Data were generated to validate the analytical method used to measure test material. The method allowed a measurement of test material as low as 0.05 ppm. Soil from the Ohio site contained trace amounts of a component which interfered with the analysis and gave false positive values for the test material. The false positive numbers did not influence the validity or interpretation of the study. The component was not the test material as it did not dissipate with time as the test material did. At the Ohio site in the top layer of soil (layer 1) from the turf plot, the concentrations of test material ranged from 0.16 ppm to 0.43 ppm, on the day of application. The concentrations decreased with time so that after 28 days, the test material in layer 1 was < 0.05 ppm in all samples taken. During the 28-day period, the amounts of test material in underlying layers of soil did not increase and all samples contained< 0.05 ppm. At the Ohio site in the top layer of soil (layer 1) from the bare ground plot, the concentrations of test material ranged from 2.00 ppm to 4.52 ppm, on the day of application. The concentrations decreased with time so that after 28 days, the test material in layer 1 ranged from 0.06 ppm to 0.21 ppm. During the 28-day period, the amounts of test material in underlying layers of soil did not increase and all samples contained < 0.05 ppm. After 60 days dissipation was complete in layer 1 with traces (0.06 ppm and 0.7 ppm) in some underlying layers.

Under the conditions of the study the test material degraded in the soil from the Ohio site over the 60-day period after application. There was no significant mobility or movement of the test material from layer 1 to the layers beneath the top 10 cm layer. The presence of crop (turf) apparently affected the dissipation of the test material. In the presence of the turf there was complete dissipation after 28 days. In the soil of the bare ground, dissipation was almost complete after 60 days. A half-life of test material residues in soil with and without turf was calculated to be 16.72 and 12.08 days, respectively.