Dichlobenil

Field studies

Administrative data

Endpoint:

field studies

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

not documented

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: BBA Guideline Part IV, 4-1

Deviations:

no

GLP compliance:

yes

Type of measurement:

Residues

Media:

Soil

Test material

Test material information

Constituent 1

Reference substance name:

Casoron G (formulated product containing dichlobenil)

IUPAC Name:

Casoron G (formulated product containing dichlobenil)

Test material form:

solid: granular

Details on test material:

- Name of test material (as cited in study report): Casoron G
- Physical state: solid
- Composition of test material, percentage of components: 6.75 % dichlobenil
- Lot: MI-0935

Results and discussion

Any other information on results incl. tables

Untreated samples of Goch-Nierswalde (1989) were used for preparation of spiked samples. The limit of quantification (LOQ) was 0.01 mg/kg. The average percent recovery found for spiked samples was 80 % for addition levels between 0.01 and 2.0 mg/kg. All recovery values were between 73 and 91 %. Spiked samples were analysed after storage at -20 °C for periods of 9 and 15 months, in order to check for storage effects. Average recoveries were 69 % indicating no major storage effects. Residues of 2,6-dichlorobenzonitrile were found predominantly in the top layer of the soil (0-10 cm) (see Table 2).

Table 2: Test material residues (mg/kg) in the topsoil layer (0-10 cm)

Time period	Goch-Nierswalde	Eschwege	Goch-Nierswalde	Nottuln
Application date	08.06.1989	15.06.1989	09.02.1990	10.02.1990
Before application	<0.01	<0.01	<0.01	<0.01
After application	5.53	5.57	1.36	2.09
1 day	5.17**	6.56	1.60	1.77
3 days	1.98	6.79	0.556	2.37
1 week	1.22	1.39	20.6	0.846
2 weeks	0.654	1.58	0.635	1.82
4 weeks	0.293	0.404	2.68	2.09
2 months	0.273	0.371	1.02	0.877
6 months	0.099	0.525	0.186	0.187
12 months	0.112	0.277	0.122	0.219
DT50 (in days)	2	19	-***	102
DT90 (in days)	54	205	-***	337

*based on the dry weight of the soil; **2 days after application; ***no curve could be fitted

The DT50 and DT90 values were determined according to Timme (1986); only for the second year Goch-Nierswalde, the values did not fit.

Applicant's summary and conclusion

Conclusions:

Under the conditions of this test, the mean DT50 was calculated to be 35 days and the mean DT90 value was 202 days. The theoretical maximum fraction formation of BAM in these field dissipation studies was 12.04 %.

Executive summary:

In a GLP compliant field dissipation study conducted in line with non-standardised guideline BBA Guideline Part IV, 4-1, the DT₅₀ and DT₉₀ values of the test material were determined. Under the conditions of the test, the DT₅₀ was calculated to be 35 days and the mean DT₉₀ value to be 202 days. The theoretical maximum fraction formation of the major metabolite in these field dissipation studies was 12.04 %.