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

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1981/09/29

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

Study was not performed under GLP conditions. The guidelines followed in this study are not stated.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1981

Report date:

1981

Materials and methods

Test guideline

Qualifier:

no guideline followed

GLP compliance:

no

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

Specific details on test material used for the study:

The test material is cyromazine.

Sampling and analysis

Analytical monitoring:

no

Remarks:

No analytical determination of the test item was performed. However, for the determination of the endpoint the amount of carbon dioxide evolved as a result of microbial respiration was measured.

Details on sampling:

The amount of carbon dioxide evolved as a result of microbial respiration was measured at 1, 3, 7 14 and 28 days.

Test substrate

Vehicle:

yes

Remarks:

methanol

Details on preparation and application of test substrate:

Soil tested: loam and silt loam soil
Microbial respiration was measured via the amount of carbon dioxide that was evolved.

The soils were blended, screened and sieved before the moisture content of both soils was determined. Available water content of the soils was also determined. Mixing 1000 g of soil with 1000 g of fine sea sand, then adding 1.0% of alfalfa meal prepared test soils. The soil stocks were adjusted to approximately 60% of their field moisture holding capacity. A 400 g fraction of each of the two soil blends was further amended by the addition of 4 mL of methanol (carrier solvent), which was then allowed to evaporate off before the soil blends were again well mixed.

Test organisms

Test organisms (inoculum):

soil

Study design

Total exposure duration:

4 wk

Test conditions

Test temperature:

25°C

Moisture:

Moisture content of soil measured before test started, refer to 'Details on test conditions'.

Details on test conditions:

2 types of soil used in testing, loam soil and silt loam soil

Loam Soil
Composition: 50.8 % sand, 35.2% silt, 14.0% clay and 2.4% organic matter
pH: 6.7
Moisture Capacity: 33.1%

Silt Loam Soil
Composition: 20.8% sand, 59.2% silt, 20.0% clay and 2.6% organic matter
pH: 6.4
Moisture Capacity: 37.6%

The test treatments and controls were placed in an incubator at 25°C for the 4-week duration of the test. The flasks were aerated twice weekly.

Nominal and measured concentrations:

nominal concentrations: 100 ppm, 10 ppm and 1 ppm

Results and discussion

Effect concentrations

Key result

Duration:

4 wk

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

respiration rate

Details on results:

In this study, cytomazine at up to 100 mg/kg has no negative effects on microbial soil respiration. In both soils there are samples in which respiration is significantly greater than the control value, however as these incidents follow no pattern their biological significance is doubtful NOEC(respiration) is 100 mg/kg (the highest rate tested).

Reported statistics and error estimates:

Data were analyzed by the analysis of variance and mean separation by Duncan's multiple range test.

Any other information on results incl. tables

Table 1: Effects of Cyromazine on soil respiration

Milliequivalents of CO2/ 50g of soil
Cyromazine
	Sterile control	Control	1 mg/kg	10 mg/kg	100 mg/kg
Silt loam soil
Sampling day
1	0.13	1.17	1.22	1.16	1.27*
3	0.06	1.35	1.62*	1.57*	1.61*
7	0.08	1.17	1.33*	1.22	1.24
14	0.05	0.98	1.06*	0.96	0.95
21	0.05	0.67	0.68	0.64	0.64
28	0.04	0.53	0.54	0.50	0.51
Total meq CO2/50g	0.41	5.87	6.45	6.05	6.22
Loam soil
1	0.12	1.00	0.97	1.00	0.96
3	0.05	1.08	1.28*	1.49*	1.38*
7	0.06	0.99	1.53*	1.46*	1.56*
14	0.05	1.02	0.98	1.07	1.07
21	0.05	1.00	1.08	1.10*	1.06
28	0.04	0.67	0.87*	0.87*	0.87*
Total meq CO2/50g	0.37	5.76	6.71	6.99	6.90

*Significantly different from the control; p< 0.05 (Duncan's multiple range test)

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Conclusions:

NOEC (respiration) is 100 mg/kg (the highest rate tested).

Executive summary:

A four week study investigating the effect of cyromazine on microbial respiration in loam and silt loam soils was carried out under controlled conditions. No guidelines were mentioned or followed in this study. Microbial respiration was measured via the amount of carbon dioxide that was evolved.

Cyromazine was used at concentrations of 100 ppm, 10 ppm and 1 ppm. The test treatments and controls were placed in an incubator at 25°C for the 4-week duration of the test. The amount of Carbon dioxide evolved as a result of microbial respiration was measured at 1, 3, 7, 14 and 28 days.

In this study, cyromazine at up to 100 mg/kg has no negative effects on microbial soil respiration. In both soils there are samples in which respiration is significantly greater than the control value, however as these incidents follow no pattern and their biological significance is doubtful. NOEC (respiration) is 100 mg/kg (the highest rate tested).