N-cyclopropyl-1,3,5-triazine-2,4,6-triamine

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil, other

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2002/05/21 to 2004/01/27

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: Pesticide Assessment Guidelines, Subdivision N, Chemistry, Environmental Fate, Series 164-1, U.S. Environmental Protection Agency. The study was designed to comply with the European Council Directive 91/414/EEC

Version / remarks:

amended by directive 95/36/EC

Deviations:

no

GLP compliance:

yes

Test type:

field trial

Test material

Test material information

Constituent 1

Reference substance name:

N-cyclopropyl-1,3,5-triazine-2,4,6-triamine

EC Number:

266-257-8

EC Name:

N-cyclopropyl-1,3,5-triazine-2,4,6-triamine

Cas Number:

66215-27-8

Molecular formula:

C6H10N6

IUPAC Name:

N2-cyclopropyl-1,3,5-triazine-2,4,6-triamine

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Soil classification:

USDA (US Department of Agriculture)

Remarks:

Soil characterisation analyses showed the soil to be a sandy loam

Year:

2002

Soil properties

Soil no.:

#1

Soil type:

sandy loam

% Clay:

8

% Silt:

24.1

% Sand:

67.9

% Org. C:

1.4

pH:

7.5

CEC:

9 meq/100 g soil d.w.

Details on soil characteristics:

Samples were taken from the control plot on the day of application and 120 days after application to the treated plot. Samples were taken from the treated plot for analysis prior to and immediately after application and then at 3 days, 7 days, 14 days 30 days, 59 days, 120 days, 244 days and 360 days after application Soil samples (0-30 cm depth) were taken for analysis using a Humax 1 corer. 20 cores were taken from the treated plot and 5 cores were taken from the control plot, at each relevant sampling time, to a depth of 30cm using a 5.0 cm diameter corer (a Humax 3 corer was used to sample 0 90 cm soil depth samples). All samples were taken at pre—determined positions.

All samples were placed in a deep freeze within 12 hours of sampling and were maintained at <-18°C during storage. The samples taken immediately before application through to the samples taken 120 days after application were transferred deep frozen from the Test Site. The samples taken 244 to 360 days after application were transferred deep frozen from the Test Site.

The samples taken immediately application through to the samples taken 120 days after application were dispatched, deep frozen via a deep freezer truck. The samples taken 244 to 360 days after application were dispatched, deep frozen via a deep freezer truck on September 2003.

Duration of test (contact time)

Soil No.:

#1

Duration:

360 d

Initial test substance concentration

Soil No.:

#1

Initial conc.:

0.28 mg/kg soil d.w.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on experimental conditions:

A single unreplicated plot for treatment was marked out, 30 m long by 6.0 m wide to give a 180 m2 treatment plot. Grass was sown four days before application resulting in sparse grass cover. A control plot was marked out, 10.0 m by m, to give a 60 m control plot. This control plot was positioned adjacent to the treatment plot. The plots were maintained by keeping the grass cover below a height of 20 cm through regular mowing throughout the study period.

Results and discussion

Half-life / dissipation time of parent compound

Half-life / dissipation time of parent compound 1

Key result

Soil No.:

#1

DT50:

2.3 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: DT50

Half-life / dissipation time of parent compound 2

Key result

Soil No.:

#1

DT50:

7.5 d

Type:

(pseudo-)first order (= half-life)

Remarks on result:

other: DT90

Transformation products:

no

Evaporation of parent compound:

yes

Volatile metabolites:

no

Residues:

no

Details on results:

Residues of cyromazine were determined in the 0 —10 cm core depth at 0 days after last application (DALA) at a level of 0.28 mg/kg dry soil, equivalent to 104% of the intended application rate. These residues had declined to <0.0025 kg-1 mg dry soil in the 0 — 10 cm core depth by 30 DALA. No residues of cyromazine, above the limit of quantification (LOQ, 0.0025 mg kg-1 were determined below the 0 10 cm core depth at any analysis interval. The Simple First Order (SFO) model gave the best statistical fit to the data with a half-life value of 2.3 days and a DT90 value of 7.5 days. Residues of melamine in soil (0—10 cm soil core depth) reached maximum levels of 0.15 mg kg-1 dry soil, 30 days after application. This residue had fallen to 0.008 mg by 360 days after application (limit of quantification 0.005 mg). Residues of melamine were determined in the 10-20 cm soil core depth at three intervals 59, 120 and 244 days after application, at levels of 0.024, 0.023 and 0.015 mg respectively. A single melamine residue of 0.0082 mg kg-1 dry soil, was determined in the 20-30 cm soil core depth at 120 days after application. No residue was determined in the 30-40 cm soil core depth at 120 days after application. No measurable residues of melamine were determined in any other 10-20 cm or 20-30 cm soil core depth, at any analysis interval.

Any other information on results incl. tables

Table 2

Cyromazine soil residues in Switzerland

	Cyromazine (mg kg^-1 dry soil)
DAA	0 - 10 cm	10 - 20 cm	20 - 30 cm
0	0.28	<0.0025	<0.0025
3	0.11	<0.0025	<0.0025
7	0.033	<0.0025	<0.0025
14	0.0068	<0.0025	<0.0025
30	<0.0025	<0.0025	<0.0025
59	<0.0025	<0.0025	<0.0025
120	<0.0025	<0.0025	<0.0025
244	<0.0025	<0.0025	<0.0025
360	<0.0025	<0.0025	<0.0025

 

 

 

Table 3

 

Melamine soil residues in Switzerland

	Melamine (mg kg^-1 dry soil)
DAA	0 - 10 cm	10 - 20 cm	20 - 30 cm
0	0.039	< 0.005	< 0.005
3	0.10	< 0.005	< 0.005
7	0.12	< 0.005	< 0.005
14	0.075	< 0.005	< 0.005
30	0.15	< 0.005	< 0.005
59	0.051	0.024	< 0.005
120	0.013	< 0.005	0.0082
244	0.011	0.023	< 0.005
360	0.0081	0.015	< 0.005

Applicant's summary and conclusion

Conclusions:

Residues of cyromazine were in the 0 —10 cm core depth at 0 days after last application (DALA) at a level of 0.28 mg/kg dry soil, to 104% of the intended application rate. No residues of cyromazine, above the limit of quantification (LOQ, 0.0025 mg were determined below the 0 10 cm core depth at any analysis interval. No measurable residues of melamine were determined in any other 10-20 cm or 20-30 cm soil core depth, at any analysis interval.

Executive summary:

A trial was carried out in Switzerland during 2002 to investigate the dissipation of cyromazine in soil following a broadcast spray treatment. A single application of cyromazine was applied at 300 g cyromazine test item as a broadcast application to the soil surface on 21 May 2002. Soil samples from the treated plot were taken immediately after the application and on 3, 7, 14, 30, 59, 120, 244 and 360 DALA (Days After Last Application). Control samples from an untreated plot were taken before application on day 0 and 120 DALA. Samples were taken from the 0-30 cm soil layer for all sampling intervals, apart from on two occasions (120 and 360 DALA), when samples were taken from the 0—90 cm soil layer. They were stored and shipped deep-frozen. Samples were analysed for cyromazine and its metabolite melamine by the analytical laboratory.

 

Cyromazine dissipated under eld conditions with a half-life of 2.3 days and a DT₉₀ of 7.5 days, using a simple first order model. Immediately after application a cyromazine residue of 0.28 mg kg^-1 dry soil, was determined in the 0—10 cm soil core depth. This residue in the 0-10 cm soil core depth had fallen below the limit of quantification (0.0025 mg kg^-1 by 30 days after application. No measurable residues of cyromazine were determined below the 0-10 cm soil core depth during the study.

 

Residues of melamine in soil (0-10 cm soil core depth) reached maximum levels of 0.15 mg kg^-1dry soil, 30 days after application. This residue had fallen to 0.008 mg by 360 days after application (limit ofquantification 0.005 mg kg^-1) Residues ofmelamine were determined in the 10—20 cm soil core depth at three intervals 59, 120 and 244 days after application, at levels of 0.024, 0.023 and 0.015 mg kg^-1 . A single melamine residue of 0.008 mg kg^-1 mg dry soil, was determined in the 20-30 cm soil core depth at 120 days after application. No residue of melamine was determined in the 30-40 cm soil core depth at 120 days after application. No measurable residues were determined in any other 10—20 cm or 20-30 cm soil core depth, at any analysis interval.