N-(2-nitrophenyl)phosphoric triamide

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005-01-12 - 2005-05-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Soil samples (100 g soil d.w.) are taken at intervals of 3 hours, 7, 14 and 28 days after application of the test item. Before the beginning of the test, the optimal glucose concentration was determined. Before the measurements, glucose (0.4 %) is added and mixed with the soil by means of a hand-stirrer. The prepared samples are placed in reaction flasks (500 mL).

The measurement of the oxygen consumption is carried out with a respirometer "BSB digi" (SELUTEC, Mossingen-Oschingen, Germany). The system records 360 02-consumption data in 24 hours.

Vehicle:

yes

Details on preparation and application of test substrate:

The test item was dissolved in water and the test solution was then mixed with the soil in the mixing machine. Water was added to the soil to achieve a moisture of 45 % of WHC.

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

20 °C ± 2 °C

Moisture:

Soil moisture: approximately 45 % of its maximum water holding capacity.

Organic carbon content (% dry weight):

1.46

Nitrogen content (% dry weight):

0.15

Nominal and measured concentrations:

0.27 mg/kg d.w.
1.33 mg/kg d.w.

Reference substance (positive control):

yes

Remarks:

Dinoterb

Key result

Duration:

28 d

Dose descriptor:

other: carbon transformation in soil

Effect conc.:

> 1 000 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: carbon transformation

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 1.33 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: carbon transformation

Results with reference substance (positive control):

The toxic standard dinoterb caused a reduction of the O2-consumption of > 25 % at the tested concentrations after 28 days and thus demonstrated the sensitivity of the test system.

Validity criteria fulfilled:

yes

Conclusions:

Based on the results of this study P 101/04 caused no short-term and long-term effects (OECD 217) on the carbon transformation in the field soil tested up to a concentration of 1.33 mg a.s. per kg soil d.w., equivalent to a field application rate of 1000 g a.s./ha.

Executive summary:

The purpose of this study was to determine the effects of the test item on the activity of soil microflora with regard to carbon transformation in a laboratory test. The test was performed in accordance to the OECD guideline 217 (2000) by measuring the short-term substrate induced respiration. The method is based on the initial respiratory response of microbial populations to which a carbon and energy source has been added (substrate-induced respiration, SIR).

This assay is based on the determination of O2 consumption of soil samples after glucose-induced respiration in a closed system for at least 24 hours. Soil samples (100 g soil d.w.) are taken at intervals of 3 hours, 7, 14 and 28 days after application of the test item. Before the beginning of the test, the optimal glucose concentration was determined. Before the measurements, glucose (0.4 %) was added and mixed with the soil by means of a hand-stirrer. The prepared samples were placed in reaction flasks (500 mL). The measurement of the oxygen consumption was carried out with a respirometer "BSB digi" (SELUTEC, Mossingen-Oschingen, Germany).

No differences greater than 25 % to the control in O2 consumption were found for any test concentration of P 101/04 at any time interval in comparison to the respective control. The coefficients of variation during the experiment were within the demanded limit (control < 15%).

Reference 2

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005-01-12 - 2005-05-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The GLP study was conducted according to an internationally accepted guideline. All study parameters are based on the specific guideline.

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Determination of the nitrogen transformation (NO3-nitrogen production) in soil enriched with lucerne meal (concentration in soil 0.5 %). Comparison of test item treated soil with a non-treated soil. 3 replicates per treatment and concentration. NH4-nitrogen, NO3- and N02-nitrogen were determined by using the Autoanalyzer II (BRAN+LUEBBE). Sampling scheme: 0. 7, 14 and 28 days after treatment.

Vehicle:

yes

Details on preparation and application of test substrate:

The test item was dissolved in water and the test solution was then mixed with the soil by means of a hand-stirrer. Water was added to the soil to achieve a moisture of 45 % of WHC. The incubation of the prepared soil was carried out in new plastic vessels (500 mL). The tops of the vessels used permitted an air exchange with negligible moisture leakage (< 1 % loss).

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

20 ± 2 °C

Moisture:

approximately 45 % of WHC

Nominal and measured concentrations:

0.27 mg/kg d.w.
1.33 mg/kg d.w.

Reference substance (positive control):

yes

Remarks:

Dinoterb

Key result

Duration:

28 d

Dose descriptor:

other: soil nitrogen transformation

Effect conc.:

> 1 000 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 1.33 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Results with reference substance (positive control):

In a separate study (study code: R 05 10 35 Nl) the reference item dinoterb caused effects greater than 25 % on the nitrogen transformation in a field soil at the tested concentrations 28 days after application.

Days after application	Control		P101/04 0.27 mg/kg soild.w.			P101/04 1.33 mg/kg soild.w.
	NO3-N [mg/kg soild.w.]	CV[%]	NO3-N [mg/kg soild.w.]	CV[%]	Deviation from control (%)	NO3-N [mg/kg soild.w.]	CV[%]	Deviation from control (%)
0	23.5	5.1	22.2	1.2	-5.7	21.9	6.3	-6.8
7	46.1	0.4	47.0	1.3	+2.0	47.0	3.6	+2.0
14	49.3	2.8	49.3	3.6	-0.1	48.4	1.6	-2.0
28	58.0	0.8	59.9	2.7	+3.2	57.9	2.1	-0.2

Validity criteria fulfilled:

yes

Conclusions:

Based on the results of this study P 101/04 caused no short term and long-term effects (OECD 216) on the soil nitrogen transformation in the field soil tested up to a concentration of 1.33 mg a.s. per kg soil dry weight, equivalent to a field application rate of 1000 g a.s./ha.

Executive summary:

The test was performed in accordance to the OECD guideline 216 (2000).

No differences greater than 25 % to the control in the nitrogen transformation were found for any concentration of P 101/04 in comparison to the respective control. The coefficients of variation during the experiment were within the demanded limit (control < 15%).

Based on the results of this study P 101/04 caused no short-term and long-term effects (OECD 216) on the soil nitrogen transformation in a field soil tested up to a concentration of 1.33 mg a.s. per kg soil dry weight, equivalent to a field application rate of 1000 g a.s. per ha.

Description of key information

In two  28 d studies  no effects were observed on soil micro organism at 1000 g/ha or 1.33 mg/kg soil dw.

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:

1.33 mg/kg soil dw